HST Phase 2 Proposal Instructions for Cycle 10

Version 10.0.2 3/7/01 HST Phase 2 Proposal Instructions for Cycle 10 Hubble Division 3700 San Martin Drive Baltimore, Maryland 21218 help@stsci.edu Operated by the Association of Universities for Research in Astronomy, Inc., for the National Aeronautics and Space Administration Revision History Version Date Editor 10.0.2 January 31, 2001 David Soderblom 10.0.1 December 29. 2000 David Soderblom • Version 10.0.2 corrects version 10.0.1 with minor formatting changes. • Version 10.0.1, issued in coordination with RPS2 release 10.0. This version is intended to be fully compliant with Cycle 10 changes to RPS2. • Version 10.0.1 is issued as a General Observer version. The most recent GO version is 10.0.2. • Shelf life: This version should not be used after March 30, 2001 without checking for a more recent version. This is not the General Observer version. If you would like some hints on how to read and use this PDF document, click on: Some PDF Pointers This is the Engineering-Only version If you can view this paragraph, you are reading the engineering-only version. See Special Note to Engineering Version Users in Chapter 1: About This Document on page 1-3 for an explanation of how to view this version properly. If you do not see this paragraph in color (green), you are not viewing this document properly. How to get help: 1. Visit STScI’s web site: http://www.stsci.edu/ where you will find resources for observing with HST and working with HST data. 2. Contact your Program Coordinator (PC) or Contact Scientist (CS). These individuals were identified in the notification letter from STScI. 3. Send e-mail to help@stsci.edu, or call 1-800-544-8125. From outside the United States, call 1-410-338-1082. Send comments or corrections to: Hubble Division Space Telescope Science Institute 3700 San Martin Drive Baltimore, Maryland 21218 E-mail: help@stsci.edu Table of Contents Part A: Phase 2 Proposal Writing ............................... 1 Chapter 1: About This Document .................... 3 Special Note to Engineering Version Users.................... 3 Document Design and Structure ....................................... 5 Changes Since the Previous Version ............................... 5 Document Presentation ........................................................ 5 Technical Content................................................................. 6 Where to Find Additional Information ............................... 7 Some PDF Pointers .............................................................. 7 Chapter 2: The Basics of Phase 2 Proposals ......................................................................... 9 How to Submit Phase 2 Information ................................. 9 What to Submit .................................................................... 11 General Instructions............................................................ 11 Proposal Information [Proposal_Information] ..................... 12 Parallel Information [Parallel_Pointing_Tolerance]............. 14 Investigators [Investigators] ................................................ 14 Abstract [Abstract] .............................................................. 14 Proposal Text Sections [Questions] ................................... 15 Target Information [Fixed_Targets, Solar_System_Targets, Generic_Targets] .................... 15 Visit Information [Visits] ...................................................... 16 Data Distribution Information ............................................. 16 Examples and General Advice ......................................... 17 Acquisitions and Pointings.................................................. 17 Examples ............................................................................ 18 Common Problems ............................................................. 18 v vi Table of Contents Consideration of Limited Resources................................... 19 Proposal Template .............................................................. 20 Proposal_Information.......................................................... 20 [Parallel_Information........................................................... 20 Abstract:.............................................................................. 21 Questions:........................................................................... 21 [Fixed_Targets.................................................................... 21 [Solar_System_Targets ...................................................... 21 [Generic_Targets ................................................................ 22 Visits ................................................................................... 22 Chapter 3: Fixed and Generic Targets [Generic _Targets] ................................................. 23 Tables and Figures ............................................................. 24 Target Number [Target_Number] .................................... 25 Target Name [Target_Name and Alternate_Names] .......................................................... 25 Catalog Name..................................................................... 26 Uncataloged Targets .......................................................... 28 Common Names................................................................. 28 Special Targets................................................................... 29 Target Description [Description] ...................................... 29 Target Position [Position] .................................................. 34 Required Accuracies of Target Positions ........................... 34 Equatorial Coordinates ....................................................... 36 Positional Offsets................................................................ 39 Region of Sky (Extended Targets) ..................................... 41 Determining Coordinates in the Guide Star Selection System (GSSS) Reference System .............................. 42 A Caution on Astrometry Prepared from STScI Plate Scans ................................................................... 43 Prohibition on the Use of GSC Version 1.2 ........................ 43 Special Catalogs................................................................. 44 Equinox for Coordinates [Equinox] ................................. 45 Source of Specified Coordinates [Coordinate_Source] ..................................................... 45 Radial Velocity or Redshift [RV_or_Z]............................ 47 Is Proper Motion or Parallax Relevant? ......................... 48 Proper Motion and Parallax Data ....................................... 48 vii Flux Data [Flux] .................................................................... 49 General Guidelines on What Flux Data to Include ............. 50 Bright-Object Constraints .................................................. 53 Comments [Comments] ..................................................... 54 Generic Targets List [Generic_Targets]......................... 55 Target Number(s) [Target_Number] ................................... 55 Target Name [Target_Name].............................................. 55 Target Description [Description] ......................................... 55 Flux Data [Flux]................................................................... 56 Comments [Comments] ...................................................... 56 Generic Target Specifications............................................. 56 Getting Coordinates Coordinated .................................... 58 Chapter 4: Solar System Targets List [Solar_System_Targets] ................................... 59 Tables and Figures ............................................................. 60 Target Number [Target_Number] .............................. 61 Target Name [Target_Name]..................................... 62 Target Description [Description] ...................................... 64 Target Position ..................................................................... 65 Target Position Level 1 [Level_1] ....................................... 66 Target Position Level 2 [Level_2] ....................................... 68 Target Position Level 3 [Level_3] ....................................... 75 Ephemeris Uncertainty [Ephem_Uncert] ................... 75 Acquisition Uncertainty [Acq_Uncert] ........................ 75 Observing Windows [Window] ......................................... 76 Default Target Windows ..................................................... 81 Flux Data [Flux] ......................................................... 82 Comments [Comments]............................................. 84 Illustrations of Orbital Longitude ...................................... 84 Examples of Target List Blocks ....................................... 85 Chapter 5: Visits and Exposures .................... 89 Tables and Figures ............................................................. 90 Visit Number [Visit_Number] ............................................ 91 Visit Priority [Visit_Priority] ................................................ 91 Visit-level Special Requirements viii Table of Contents [Visit_Requirements] ..................................................... 92 On Hold Comments [On_Hold_Comments].................. 92 Visit Comments [Visit_Comments] .................................. 93 Exposure Number [Exposure_Number] ......................... 93 Target Name [Target_Name] ........................................... 93 Astronomical Targets.......................................................... 94 Special Targets................................................................... 94 Instrument Configuration [Config] ................................... 95 Operating Mode [Opmode] ............................................... 96 Aperture or Field of View [Aperture] ............................... 96 Spectral Element [Sp_Element]...................................... 97 Central Wavelength or Range if Grating or Prism Used [Wavelength] ............................................ 97 Optional Parameters [Optional_Parameters] ............... 98 Number of Times to Iterate the Exposure [Number_of_Iterations] ................................................. 98 Time per Exposure [Time_Per_Exposure] .................... 98 Exposure-level Special Requirements [Special_Requirements] ............................................. 100 Exposure-level Comments [Comments] ...................... 100 Chapter 6: Parallel Science Exposures.................................................................... 101 Parallel Science Limitations ............................................ 102 Pure Parallels ..................................................................... 103 Coordinated Parallels ....................................................... 105 Instrument Configuration .................................................. 105 Targets.............................................................................. 106 Special Requirements....................................................... 107 Optional Parameters......................................................... 109 Ordering Restrictions and Interpretations ......................... 110 Efficiency Considerations ................................................. 110 ix Chapter 7: Special Requirements [Visit_Requirements and Special_Requirements] ................................... 111 Tables and Figures .......................................................... 112 Introduction to Special Requirements: Syntax and Rules ......................................................... 112 Visit-level Special Requirements ................................... 117 Guiding ............................................................................. 117 Target Orientation............................................................. 119 Special Observation Requirements .................................. 129 Timing Requirements........................................................ 131 Conditional Requirements ................................................ 134 Exposure-level Special Requirements ......................... 134 Target Acquisition ............................................................. 134 Target Position.................................................................. 137 Special Observation Requirements .................................. 139 Special Communications Requirements........................... 141 Timing Requirements........................................................ 143 Implementation Special Requirements (Engineering)................................................................. 147 Visit Special Requirements (Engineering) ........................ 147 Exposure Special Requirements (Engineering)................ 148 Chapter 8: Pointings and Patterns.............. 153 Pointing the Telescope .................................................... 153 Introduction to Patterns .................................................... 154 How to Fill Out the Pattern Parameters Form ............ 155 Pattern Parameters........................................................... 156 Convenience Patterns ...................................................... 159 WFPC2 Patterns............................................................... 160 STIS Patterns ................................................................... 162 ACS Patterns (for Cycle 11) ............................................. 165 NICMOS Patterns (for Cycle 11) ...................................... 167 x Table of Contents Part B: Supported Science Instruments ........... 177 Chapter 9: Wide Field Planetary Camera 2 (WFPC2) ............................................... 179 Tables and Figures ........................................................... 180 Introduction to WFPC2 ..................................................... 180 Mode = IMAGE Configuration = WFPC2 ............................................. 182 Aperture or FOV ............................................................... 183 Spectral Elements............................................................. 184 Wavelength....................................................................... 184 Optional Parameters......................................................... 185 Number of Iterations ......................................................... 187 Time Per Exposure ........................................................... 187 Mode = DECON Configuration = WFPC2 (Restricted) ...................... 188 Target Name..................................................................... 188 Aperture or FOV ............................................................... 188 Spectral Elements............................................................. 188 Time Per Exposure ........................................................... 189 Mode = POM Configuration = WFPC2 (Restricted) ...................... 189 Optional Parameters......................................................... 190 Mode = AFM Configuration = WFPC2 (Restricted) ...................... 190 Optional Parameters......................................................... 191 Tabular Reference Data .................................................. 191 WFPC2 Internal Calibration Targets (Available but Unsupported) ...................................... 195 WFPC2 Aperture Coordinate System .......................... 197 Chapter 10: Space Telescope Imaging Spectrograph (STIS) ..................... 199 Tables and Figures ........................................................... 200 Introduction to STIS .......................................................... 200 xi Mode = ACQ Configuration = STIS/CCD ................................................................. 203 Aperture or FOV ............................................................... 203 Spectral Element .............................................................. 204 Optional Parameters......................................................... 204 Number of Iterations ......................................................... 205 Time Per Exposure ........................................................... 205 Special Requirements....................................................... 205 Mode = ACQ/PEAK Config = STIS/CCD ..................................................... 206 Aperture or FOV ............................................................... 206 Spectral Element .............................................................. 206 Optional Parameters......................................................... 207 Number of Iterations ......................................................... 209 Time Per Exposure ........................................................... 209 Special Requirements....................................................... 209 Mode = ACCUM Config = STIS/CCD ..................................................... 210 Aperture or FOV ............................................................... 210 Spectral Element .............................................................. 210 Wavelength....................................................................... 210 Optional Parameters......................................................... 211 Number of Iterations and Time Per Exposure .................. 214 Mode = ACCUM Config = STIS/FUV–MAMA, Config = STIS/NUV–MAMA ...................................... 215 Aperture or FOV ............................................................... 215 Supported Spectral Elements ........................................... 215 Wavelength....................................................................... 216 Optional Parameters......................................................... 216 Number of Iterations and Time Per Exposure .................. 218 Mode = TIME–TAG Configuration = STIS/FUV–MAMA, Configuration = STIS/NUV–MAMA .......................... 218 Aperture or FOV ............................................................... 218 Spectral Element .............................................................. 218 Wavelength....................................................................... 219 Optional Parameters......................................................... 219 Number of Iterations and Time Per Exposure .................. 220 Special Requirements....................................................... 220 xii Table of Contents Mode = ALIGN (Restricted) Configuration = STIS (Restricted) ............................ 221 Target Name..................................................................... 221 Aperture or FOV ............................................................... 221 Spectral Element .............................................................. 221 Wavelength....................................................................... 221 Optional Parameters......................................................... 222 Number of Iterations ......................................................... 222 Time Per Exposure ........................................................... 222 Mode = ANNEAL (Restricted) Configuration = STIS (Restricted) ............................ 223 Target Name..................................................................... 223 Aperture or FOV ............................................................... 223 Spectral Element .............................................................. 223 Wavelength....................................................................... 223 Optional Parameters......................................................... 223 Number of Iterations ......................................................... 223 Time Per Exposure ........................................................... 223 Mode = MSMOFF (Restricted) Configuration = STIS (Restricted) ............................ 224 Target Name..................................................................... 224 Aperture or FOV ............................................................... 224 Spectral Element .............................................................. 224 Wavelength....................................................................... 224 Optional Parameters......................................................... 224 Number of Iterations ......................................................... 225 Time Per Exposure ........................................................... 225 STIS Central Wavelengths .............................................. 226 STIS Internal Calibration Targets .................................. 227 Target_Name = WAVE ..................................................... 227 Aperture ............................................................................ 228 Spectral Element .............................................................. 228 Optional Parameter........................................................... 228 Target_Name = CCDFLAT ............................................... 229 Aperture ............................................................................ 231 Spectral Element .............................................................. 231 Target_Name = BIAS (Restricted).................................... 231 Aperture ............................................................................ 231 Spectral Element .............................................................. 231 xiii Target_Name = DARK (Restricted) .................................. 231 Aperture ............................................................................ 232 Spectral Element .............................................................. 232 STIS Coordinate System ................................................. 232 The Official STIS Aperture List for Cycle 10 ............... 234 Chapter 11: Fine Guidance Sensors (FGS) ................................................................................ 243 Tables and Figures ........................................................... 244 Introduction to the FGS .................................................... 244 Mode = POS Configuration = FGS ................................................... 245 Aperture or FOV ............................................................... 246 Spectral Element .............................................................. 246 Optional Parameters......................................................... 246 Special Requirements....................................................... 248 Time Per Exposure ........................................................... 248 Mode = TRANS Configuration = FGS ................................................... 248 Aperture or FOV ............................................................... 249 Spectral Element .............................................................. 249 Optional Parameters......................................................... 249 Time Per Exposure ........................................................... 250 Special Requirements....................................................... 250 Tables and Illustrations .................................................... 251 Chapter 12: Advanced Camera for Surveys (ACS) ................................................. 253 Tables and Figures ........................................................... 254 Introduction to the ACS .................................................... 254 Mode = ACCUM Configuration = ACS/WFC......................................... 256 Aperture or FOV ............................................................... 256 Spectral Element .............................................................. 257 Wavelength....................................................................... 257 Optional Parameters......................................................... 257 Number of Iterations ......................................................... 260 Time Per Exposure ........................................................... 260 xiv Table of Contents Mode = ACCUM Configuration = ACS/HRC ......................................... 261 Aperture or FOV ............................................................... 261 Spectral Element .............................................................. 261 Wavelength....................................................................... 261 Optional Parameters......................................................... 262 Number of Iterations ......................................................... 265 Time Per Exposure ........................................................... 265 Mode = ACQ Configuration = ACS/HRC ......................................... 265 Aperture or FOV ............................................................... 265 Spectral Element .............................................................. 266 Wavelength....................................................................... 266 Optional Parameters......................................................... 266 Number of Iterations ......................................................... 266 Time Per Exposure ........................................................... 266 Mode = ACCUM Configuration = ACS/SBC.......................................... 267 Aperture or FOV ............................................................... 267 Spectral Element .............................................................. 267 Wavelength....................................................................... 267 Optional Parameters......................................................... 267 Number of Iterations ......................................................... 268 Time Per Exposure ........................................................... 268 Mode = ALIGN Configuration = ACS/WFC or ACS/HRC (Restricted) ................................................ 268 Target Name..................................................................... 268 Aperture or FOV ............................................................... 268 Spectral Element .............................................................. 268 Wavelength....................................................................... 269 Optional Parameters......................................................... 269 Number of Iterations ......................................................... 269 Time Per Exposure ........................................................... 269 Special Requirements....................................................... 269 Mode = ANNEAL Configuration = ACS (Restricted) ............................ 270 Target Name..................................................................... 270 Aperture or FOV ............................................................... 270 xv Spectral Element .............................................................. 270 Wavelength....................................................................... 270 Optional Parameters......................................................... 270 Number of Iterations ......................................................... 270 Time Per Exposure ........................................................... 270 Tabular reference Data .................................................... 271 Spectral Elements for WFC and HRC .............................. 271 Ramp Filter Wavelength Ranges...................................... 273 Spectral Elements for ACS/SBC....................................... 273 Chapter 13: Near Infrared Camera and Multi-Object Spectrometer (To be supported in Cycle 11) (NICMOS) ...................................................................... 275 Tables and Figures ........................................................... 276 Introduction to NICMOS................................................... 276 Mode = ACCUM Configuration = NIC1 or NIC2 or NIC3 ................... 278 Aperture or FOV ............................................................... 278 Spectral Elements............................................................. 278 Wavelength....................................................................... 279 Optional Parameters......................................................... 279 Time Per Exposure ........................................................... 281 Special Requirements....................................................... 282 Mode = MULTIACCUM Configuration = NIC1 or NIC2 or NIC3 ................... 282 Aperture or FOV ............................................................... 282 Spectral Elements............................................................. 282 Wavelength....................................................................... 282 Optional Parameters......................................................... 283 Time Per Exposure ........................................................... 285 Special Requirements....................................................... 285 Mode = ACQ Configuration = NIC2 .................................................. 289 Aperture or FOV ............................................................... 289 Spectral Elements............................................................. 289 Wavelength....................................................................... 289 Optional Parameters......................................................... 289 xvi Table of Contents Number of Iterations ......................................................... 289 Time Per Exposure ........................................................... 289 Special Requirements....................................................... 290 Mode = BRIGHTOBJ Configuration = NIC1 or NIC2 or NIC3 (Available but Unsupported) ...................................... 290 Aperture or FOV ............................................................... 290 Spectral Elements............................................................. 291 Wavelength....................................................................... 291 Optional Parameters......................................................... 291 Time Per Exposure ........................................................... 291 Special Requirements....................................................... 291 Mode = ALIGN Configuration = NIC1 or NIC2 or NIC3 (Restricted) .................................................................... 292 Target Name..................................................................... 292 Aperture or FOV ............................................................... 292 Spectral Elements............................................................. 292 Wavelength....................................................................... 292 Optional Parameters......................................................... 293 Number of Iterations ......................................................... 293 Time Per Exposure ........................................................... 294 Special Requirements....................................................... 294 Tabular Data ....................................................................... 294 TPG_TIME Values............................................................ 294 NICMOS Apertures........................................................... 295 NICMOS Spectral Elements ............................................. 296 NICMOS Internal Calibration Targets (Available but Unsupported)......................................................... 298 Illustrations .......................................................................... 299 Chapter 14: Cosmic Origins Spectrograph (COS) ........................................... 303 Tables and Figures ........................................................... 304 Introduction to the COS ................................................... 304 Mode = TIME-TAG Configuration = COS/NUV ......................................... 304 Aperture or FOV ............................................................... 304 Spectral Element .............................................................. 304 xvii Wavelength....................................................................... 305 Additional Parameter ........................................................ 305 Number of Iterations ......................................................... 306 Time Per Exposure ........................................................... 306 Special Requirements....................................................... 306 Tabular reference Data .................................................... 306 Part C: Engineering Modes (Limited Access) ......................................................... 309 Chapter 15: Corrective Optics Space Telescope Axial Replacement (Restricted) (COSTAR) ..................................... 311 Mode = DOB, Configuration = COSTAR (Restricted).................... 313 Optional Parameters......................................................... 313 Mode = FOC, Configuration = COSTAR (Restricted).................... 313 Optional Parameters......................................................... 314 Mode = SENSOR, Configuration = COSTAR (Restricted).................... 314 Optional Parameters......................................................... 314 Mode = FOS, Configuration = COSTAR (Restricted)................ 315 Optional Parameters ................................................... 315 Mode = GHRS, Configuration = COSTAR (Restricted).................... 316 Optional Parameters......................................................... 316 Chapter 16: S/C Mode (Restricted) ............. 317 Mode = DATA Configuration = S/C (Restricted) .............................. 318 Aperture or FOV ............................................................... 318 Special Requirements....................................................... 318 Mode = POINTING Configuration = S/C (Restricted) .............................. 319 Aperture or FOV ............................................................... 319 xviii Table of Contents List of Figures Orbital Longitude for Satellites ...................................................... 84 Orbital Longitude for Planets ......................................................... 85 ORIENTation computation for WFPC2........................................ 121 ORIENTation computation for STIS. ........................................... 123 ORIENTation computation for FGS1R, in TRANS mode. ........... 124 WFPC2 Aperture Coordinate System.......................................... 197 STIS coordinate system (shown projected onto the sky, as used with the POS TARG Special Requirement). ............. 233 The FGS POS TARG and interferometer coordinate systems. ... 252 NICMOS Coordinate System....................................................... 299 Definition of Orientation for NICMOS. ......................................... 300 Guide-Star Availability with NICMOS Patterns. ........................... 301 xix xx List of Tables Table 2.1: Limited-Resource Special Requirements ..................... 20 Table 3.1: Designations of Special Targets................................... 29 Table 3.2: Target Categories......................................................... 30 Table 3.3: Descriptive Keywords for STAR and EXT-STAR ......... 31 Table 3.4: Descriptive Keywords for STELLAR CLUSTER and EXT-CLUSTER ........................................................................ 32 Table 3.5: Descriptive Keywords for GALAXY .............................. 32 Table 3.6: Descriptive Keywords for CLUSTER OF GALAXIES ............................................................................... 32 Table 3.7: Descriptive Keywords for ISM and EXT-MEDIUM........ 33 Table 3.8: Descriptive Keywords for UNIDENTIFIED.................... 33 Table 3.9: Descriptive Keywords for CALIBRATION..................... 33 Table 3.10: Discrete Features and Descriptors for All Categories................................................................................ 34 Table 3.11: Required Coordinate Accuracies................................ 36 Table 3.12: Required Coordinate Accuracies for NICMOS (Restricted)............................................................................... 36 Table 3.13: Formats for Specification of Target Flux Data ............ 52 Table 3.14: Bright-Object Constraints ........................................... 54 Table 3.15: Bright-Object Constraints for NICMOS (Restricted)............................................................................... 54 Table 4.1: Solar System Standard Targets ................................... 63 Table 4.2: Target Description Keywords ...................................... 64 Table 4.3: Positional Parameters for TYPE = COMET.................. 67 Table 4.4: Positional Parameters for TYPE = ASTEROID ........... 67 Table 4.5: Parameters for TYPE = PGRAPHIC ........................... 69 Table 4.6: Parameters for TYPE = POS_ANGLE ........................ 70 Table 4.7: Parameters for TYPE = MAGNETO ............................ 71 xxi xxii List of Tables Table 4.8: Parameters for TYPE = TORUS .................................. 71 Table 4.9: Parameters for TYPE = SAT ....................................... 73 Table 4.10: Parameters for TYPE = PCENTRIC (Available but Unsupported) .................................................... 74 Table 4.11: Keywords for Observing Windows ............................ 77 Table 4.12: Operators for Observing Windows ............................ 77 Table 4.13: Formats for Specification of Target Flux Data ............ 83 Table 5.1: Internal Calibration Target Names ............................... 94 Table 5.2: Special External Target Names.................................... 95 Table 5.3: Instrument Configurations and Operating Modes......... 95 Table 5.4: Aperture and Field of View Names............................... 96 Table 7.1: Supported Formats for Visit Level Special Requirements......................................................................... 114 Table 7.2: Supported Formats for Exposure Level Special Requirements........................................................................ 115 Table 7.3: Accuracies of Guiding Modes..................................... 117 Table 7.4: Instrument Orientations with respect to U3-Direction ........................................................................... 126 Table 7.5: Approximate Separation and Orientations between Instrument Detectors ............................................... 127 Table 9.1: Supported Instrument Parameters for WFPC2 .......... 181 Table 9.2: WFPC2 Apertures ...................................................... 184 Table 9.3: Valid WFPC2 Exposure Times (seconds) .................. 191 Table 9.4: WFPC2 Supported Spectral Elements (Filters) .......... 192 Table 9.5: Linked Spectral Element/Aperture Combinations for Wood’s and Quadrant Filters ................................................. 194 Table 9.6: Internal Calibration Targets for the WFPC2 (Available but Unsupported) .................................................. 196 Table 10.1: Supported Optional Parameters for STIS Instrument Modes .................................................................. 201 Table 10.2: Supported Central Wavelengths for STIS Gratings ................................................................................. 226 Table 10.3: Time_Factor for Spectral Elements and Wavelenghts. ......................................................................... 230 Table 10.4: Supported STIS Apertures ....................................... 235 Table 11.1: Supported Instrument Parameters for the FGS........ 245 Table 11.2: Spectral Elements for the FGS................................. 251 xxiii Table 11.3: Internal Calibration Targets for the FGS (Restricted)............................................................................. 251 Table 12.1: Supported Instrument Parameters for the ACS........ 255 Table 12.2: Internal calibration Targets for the ACS ................... 256 Table 12.3: Spectral Elements for use with ACS/WFC and ACS/HRC Configurations....................................................... 272 Table 12.4: Wavelength Ranges for the WFC/HRC Ramp Filters........................................................................... 273 Table 12.5: Spectral Elements for use with the ACS/SBC Configuration.......................................................................... 273 Table 13.1: Supported Instrument Parameters for NICMOS....... 277 Table 13.2: Predefined Sample Sequences for MULTIACCUM Mode (seconds) ............................................ 287 Table 13.3: Quantized Legal NICMOS TPG Expose Times........ 294 Table 13.4: NICMOS Apertures .................................................. 296 Table 13.5: Spectral Elements for the NICMOS.......................... 297 Table 13.6: Internal Calibration Targets for the NICMOS ........... 298 Table 14.1: Supported Instrument Parameters for the COS ...... 304 Table 14.2: COS Spectral Elements and Central Wavelengths ......................................................................... 307 Table 15.1: Instrument Parameters for the COSTAR.................. 312 xxiv List of Tables PART A: Phase 2 Proposal Writing The chapters in this part explain how to use the Phase 2 Instructions, how to fill out the RPS2 template, and how to submit the information to STScI. It will also explain where to go for help, and describe the information that must be submitted to STScI by GOs and GTOs during Phase 2. 1 2 CHAPTER 1: About This Document In this chapter. . . Document Design and Structure / 5 Changes Since the Previous Version / 5 Document Presentation / 5 Technical Content / 6 Where to Find Additional Information / 7 Some PDF Pointers / 7 Special Note to Engineering Version Users The Phase 2 Proposal Instructions are issued in two forms, a GO version, and this one, an Engineering version. GO text is in black. Engineering-only text is in color and has change bars. Any text seen in color is not provided to the GOs. Text in green signifies comments for the engineering-only version. Engineering-only options are of two types. • Available-but-Unsupported items may be used by GOs and GTOs if there is strong scientific justification. In such cases calibrations will not be provided by STScI. There is limited user support from STScI for the reduction and analysis of data taken with Available-but-Unsupported modes, and that support may be provided at a low priority. Available-but-Unsupported-mode observations will be taken on a shared-risk basis, which means that observations that fail due to the use of the Available-but-Unsupported capability will not be repeated. Available-but-Unsupported modes can only be invoked if the Avail_Ok flag is set in the Phase 2 program. • Available but Unsupported modes are shown in magenta. 3 4 Chapter 1: About This Document • Restricted items generally have no valid scientific use at all and are only used for instrumental calibration and maintenance. These should never be used without the approval of an Instrument Scientist for the SI in question. The word Restricted accompanies the descriptions of Restricted items. Restricted modes are shown in red. Use with caution! Note: Text in blue shows cross-references to other parts of this document. .Note to users of the Engineering version: Cross-references in non-black text are active (you can click on them and jump to that location), but they are not in blue for reasons beyond my control. Proposals to observe with Hubble Space Telescope (HST) are reviewed in two phases managed by the Space Telescope Science Institute (STScI). In Phase 1, proposers submitted an Observation Summary for review by the Telescope Allocation Committee (TAC). The Observation Summary provides only general descriptions of the targets and of the proposed observations. The TAC review results in a list of accepted proposals. During Phase 2, General Observers (GOs) with accepted proposals, as well as Guaranteed Time Observers (GTOs), must provide complete details of their proposed observations so that STScI can conduct a full technical feasibility review. The Phase 2 information will then be used to schedule the actual observations and obtain data. This document, the Phase 2 Proposal Instructions, has the following purposes: • To describe the information that must be submitted to STScI by GOs and GTOs during Phase 2. • To describe how to fill out the RPS2 (Remote Proposal Submission 2) template. • To show how to submit the information to STScI. Document Design and Structure 5 It is assumed that readers of this document are familiar with the Cycle 10 Call for Proposals, issued in June, 2000, and with the Instrument Handbooks. Document Design and Structure These Instructions are meant to be read on-line, not on paper, although many readers may wish to print selected portions. Many cross-references have been added to make navigation easy and convenient. A comprehensive Table of Contents allows you to go directly to chapters, sections, subsections, tables, and figures. These Instructions are divided into Parts, mostly to organize similar material, but you can find navigation pointers at the beginning of each Part. Each chapter starts with a listing of sections and subsections, each linked to its page. Tables of information and illustrations are also listed and cross-referenced. Most chapters have a table of specific items discussed there that lies one or two pages after the start of the chapter; this table has links for convenient navigation. An index has also been provided. Changes Since the Previous Version Document Presentation The RPS2 Manual The RPS2 Users Manual for Cycle 10 is not in this version of the Phase 2 Proposal Instructions, but can be reached at: http://www.stsci.edu/public/rps2-users.html The Engineering Version (Engineering) The types of engineering-only text were described in the first four paragraphs of the Engineering version in this chapter. Note that change bars remain as an aid to identification, but the parallel bars next to individual blocks of text have been deleted. Instead, any text that is engineering-only has (almost) always been set as a separate paragraph. 6 Chapter 1: About This Document On paper, these colors print as shades of grey. The critical items are those tagged “Restricted,” and those always have that word at the beginning of such an entry. Navigation The navigation buttons have been removed from the individual pages of the document because the same functions are available in Acrobat, the PDF reader. Use the table of contents that runs down the left side of the window to go to chapters, the Table of Contents, or index. Web versus Paper We urge all proposers to access this information via the web. The web versions of the Phase 2 Proposal Instructions will be the only ones that you can be certain are up-to-date. They are easily downloaded and printed if you wish, but the on-line versions should provide superior cross-referencing and accessibility. It is especially important that users of the Engineering version use the on-line document to ensure they are viewing the most recent changes. Reader Feedback We have strived to present this critical, detailed, and complex information in a form that allows it to be used accurately and effectively. Your comments on its good and bad qualities will help us in the future; send e-mail to help@stsci.edu. Technical Content Available Science Instruments for Cycle 10 Neither NICMOS nor FOC is supported for use in Cycle 10. The only supported instruments in Cycle 10 are WFPC2, STIS, and FGS. The Advanced Camera for Surveys (ACS) and NICMOS should be available in Cycle 11. Instrument Modes, Special Requirements, etc. Some changes have been made to these Instructions since the previous version to correct errors and omissions, and to document new modes or Where to Find Additional Information 7 options. There are too many to list, but as long as you use the most recent version the information provided should reflect our current state of knowledge. Where to Find Additional Information You will probably need to consult the Instrument Handbooks for one or more Science Instruments as you write your Phase 2 proposal. They are also available on the Web. However, in this version of these Instructions there are not yet cross-links to the Instrument Handbooks. There are some policies that were delineated in the Call for Proposals, which asked for Phase 1 proposals. You may wish to review those, particularly the sections discussing limited resources. Some PDF Pointers If you’re new to Adobe’s Portable Document Format (PDF), here are some hints that you may find useful: • PDF has links, just like HTML. Everything in blue in this document is a link you can click on to go somewhere else. • “Table of Contents” and “Index” take you to those chapters, which are designed to provide a thorough listing of the information available. • PDF can print selected pages while HTML cannot. Note that the page numbers you enter are PDF’s sequential numbers (look at the bottom of the Acrobat window to see where you are). • You can move up or down page by page using the scroll bar on the right of your Acrobat window; just click above or under the indicator that shows your relative position. You can also click and hold on this indicator to speed through the document. • If you wish to save this document as a PDF file on your local machine, click with your right mouse button on the Institute’s web page that has the Phase 2 information at the spot where you link to the PDF file. In other words, your left button opens the file in Acrobat, but the right button lets you save the file if you pull down to “Save Link as.” • Look at Acrobat’s help facility (the help button is in the upper right corner of the Acrobat window) for more pointers. 8 Chapter 1: About This Document If you are familiar with what is developing on the web you will see that PDF is an emerging standard for the commercial sector because it is easily produced with modern documentation software and has many excellent features. We welcome your comments and thoughts for improving how we provide information to you. CHAPTER 2: The Basics of Phase 2 Proposals For an explanation of this engineering-only version, see Special Note to Engineering Version Users in Chapter 1: About This Document on page 3. In this chapter . . . How to Submit Phase 2 Information / 9 What to Submit / 11 General Instructions / 11 Examples and General Advice / 17 Table 2.1: Limited-Resource Special Requirements / 20 Proposal Template / 20 How to Submit Phase 2 Information The computer software used to schedule and execute HST observations can interpret the proposal information only if it is in the proper format. Therefore, proposals must be filled out accurately, completely, and in strict accordance with the instructions in this document. Observers now have the capability and responsibility (with the help of their Program Coordinator and Contact Scientist) for creating and submitting proposals that are not only syntactically correct but also feasible and schedulable. This is possible using the revised Remote Proposal Submission (RPS2) software. An observer prepares the Phase 2 information at his or her home institution and then submits it electronically to STScI using the RPS2 software. They will be provided with a template RPS2 file which, for GOs, contains all relevant information from their Phase 1 submission (e.g. the title and 9 10 Chapter 2: The Basics of Phase 2 Proposals abstract) already filled in. Observers should consult the RPS2 User’s Manual for detailed instructions on how to install and use RPS2 at their home institutions. This will enable the proposal to be checked before electronic submission to STScI. (Observers without access to suitable computer equipment should contact their Program Coordinator to make other arrangements.) To get the User’s Manual, go to: The RPS2 software allows the proposer to create a Phase 2 program which is free from errors and is feasible and schedulable. However, observers are urged to discuss their proposals and any problems encountered in filling out the Phase 2 template or using the RPS2 software with their assigned Program Coordinator and/or Contact Scientist. The RPS2 submission system will give the submitter an automatic electronic acknowledgment. This will generally be followed in a few days by an acknowledgment from the Program Coordinator. If, at the time of submission, the proposal contains outstanding errors, the RPS2 submission system will give a warning, but will allow the proposal to be submitted. However, the proposal will be flagged as having outstanding errors, and the observer will be contacted by the Program Coordinator within a few days to discuss how to proceed (if they have not discussed this already). The resolution of errors in the Phase 2 Program is the responsibility of the Principal Investigator. The fact that RPS2 may allow you to submit a program that contains errors does not mean that program can or will be scheduled. These Instructions are, essentially, a programming language, and therefore they need to compile successfully before they can execute. We strive to make RPS2 useful and complete for preparing and checking your Phase 2 program, but it is nevertheless imperfect. On rare occasions syntax errors are not detected, and RPS2 does not check for guide stars. Caution and common sense are needed. In particular, many problems arise when programs are edited directly as text rather than using the facilities in PED. If you edit outside of PED, be sure to check the output from the DG to see if anything was lost, and consult with your Program Coordinator for advice. What to Submit 11 What to Submit Observers must submit the Remote Proposal Submission Two (RPS2) file to STScI by the Phase 2 deadline. It will contain the following: • Updated general information section. This section contains the title, proposer information, abstract, and proposal text sections. Please note that some general information is very useful for a thorough and helpful technical review of your proposal. You may wish to include parts of your Phase 1 science discussion, but please note that all the Phase 2 information that you provide is made freely available via the web. • Target List. One or more of the Fixed, Solar System, or Generic Target Lists must be completed. If necessary, proper motion and parallax information should be supplied for fixed targets. Detailed instructions for filling out the target lists, as well as the proper motion and parallax information, are provided in Chapter 3: Fixed and Generic Targets [Generic _Targets] on page 23 and Chapter 4: Solar System Targets List [Solar_System_Targets] on page 59 of this document. • Visit and Exposure Specifications. The Visit and Exposure Specifications must be completed. General instructions for completing the Visit/Exposure Template are provided in Chapter 5: Visits and Exposures on page 89 of this document. General Instructions In this section, we describe how to fill out the RPS2 template (the #.prop file, where # is the Phase 2 proposal identification number which will be supplied by your Program Coordinator). Information about retrieving samples of completed RPS2 files is presented in Examples and General Advice on page 17, along with a discussion of common questions and problems observers might have when filling out the template. Note the following general instructions and conventions when filling out the RPS2 template: • Entries must conform precisely to the formats specified in this document and their order must be correct as well (see Proposal Template on page 20). 12 Chapter 2: The Basics of Phase 2 Proposals • Some information transferred from your Phase 1 proposal to the Phase 2 template may no longer be clear. For example, a table originally formatted in LaTeX may now be an unintelligible run-on of symbols. Please verify that all general information intended for inclusion in Phase 2 is readable. • Information that must be entered into the RPS2 template exactly as shown is indicated in BOLD TYPE. Items to be replaced by specific entries are enclosed in <angular brackets>. For example, SEQ <exposure-list> NON-INT could become SEQ 2-3 NON-INT or SEQ 10, 23, 15 NON-INT, depending on the appropriate exposure numbers. • Proposal data may contain only standard ASCII characters. All other symbols must be spelled out. Greek letters must be spelled out (e.g. BETA-LYR, H-ALPHA). The degree sign should be replaced with “D” (e.g. BD+16D516). Subscripts and superscripts are not allowed. • Information that cannot be made to conform to the required formats may be entered in a “Comments” line. Comment lines are not interpreted by the software but are maintained in the database and do appear on printouts of the forms. • Keywords on the Target Lists and Visit and Exposure Specifications can be deleted if no entry is required (i.e., the value is not relevant to your observations or the default value is acceptable). If you are unable to use the RPS2 software, please contact your Program Coordinator (listed in your notification letter) to make other arrangements. Proposal Information [Proposal_Information] This block contains basic information about the proposal including the • Title, • Proposal_Category, and • Cycle. The template you receive from your Program Coordinator will have all the above filled out based on your Phase 1 submission. For those Phase 2 submissions that are not based on a Phase 1 proposal (e.g., GTO programs), the Proposal_Category should be selected from one of the following: GO (General Observer) SNAP (snapshot proposals) GO/DD (Director’s Discretionary time) General Instructions 13 The following proposal categories may also be used internally to STScI, but only as Restricted: CAL/WF2, CAL/FOC, CAL/NIC, CAL/STIS, CAL/AST, CAL/OS, CAL/OTA, ENG/WF2, ENG/NIC, ENG/STIS, ENG/FGS, ENG/AST, ENG/COS, ENG/FOC, ENG/SC, ENG/OTA, NASA, ERO, SM3. GTO/ACS, CAL/ACS, ENG/ACS. The following are available for SM3B: SM3/ACS, SM3/ERO, SM3/FGS, SM3/NIC, SM3/STIS, SM3/WF2, SM3/SC. Note the combination of “SM3” plus the Cycle number distinguished between SM3A and SM3B. New proposal types can be created, but only if needed. A Proposal_Category of SNAP is used for “snapshot” programs. By their nature these programs take advantage of otherwise-unused blocks of telescope time for relatively short exposures. SNAP exposures therefore must carry as few restrictions as possible. In particular, Special Requirements should not ordinarily be used with SNAP programs (consult with your Program Coordinator if you feel you need to do so). Also, less-restrictive guiding is ordinarily used for SNAP exposures because that is adequate for short exposures and because that helps extend FGS lifetimes. Some special policies apply to SNAP programs. In particular, STScI will not repeat failed SNAP exposures. The Cycle should be 10; multiple values of Cycle are not permitted. In pure parallel proposals (see Pure Parallels on page 103), the suffix /PAR should be added to the appropriate type from the above list. This identifies the proposal as a pure parallel. The Avail_Ok keyword is intended for GOs and GTOs who want to use “Available but Unsupported” engineering-only options, which are described throughout this document. The only legal value for Avail_Ok is YES. GOs and GTOs may use Available but Unsupported options only if this keyword has been enabled by the Contact Scientist, who will need to determine that the use of an Available but Unsupported mode is justified. If the Avail_Ok keyword is enabled, RPS2 will perform full error checking on exposures with Available but Unsupported options in GO and GTO proposals. Otherwise RPS2 will report a syntax error and any other problems with the exposure will not be detected. Proposal types beginning with CAL, ENG, or SM3 may use any engineering-only option and are not required to supply the Avail_Ok keyword. 14 Chapter 2: The Basics of Phase 2 Proposals Parallel Information [Parallel_Pointing_Tolerance] This information is required with pure parallel proposals (those with a Proposal_Category ending in /PAR). It does not apply to primary proposals. The Parallel_Pointing_Tolerance gives the maximum acceptable variation in pointing at the parallel aperture during a parallel visit. The units are arcsec but must be explicitly stated. The number must be non-negative (e.g., 10"). This will normally be set to the maximum pointing change that still allows exposures taken at slightly different pointings to be combined later during data analysis. Investigators [Investigators] This block contains the names of the Principal Investigator (PI_Name), all Co-Investigators (CoI_Name), and their institute affiliations (PI_Institution and CoI_Institution). This information has been filled out based on the Phase 1 submission. If one of the Co-Investigators (or other individuals) is to serve as the contact for a program, then the Contact keyword should be set to Y. The Contact is the person the Principal Investigator has designated to receive all (non-budgetary) questions/information on the program and to be the official voice for the team. Only one person may be designated as the Contact. Once designated, only the Contact may make Change Requests so that conflicting requests are not made. If any of the Investigators have changed addresses between the Phase 1 and Phase 2 submissions (or any time after the Phase 1 submission), please contact your Program Coordinator with the updated address. You cannot use the Phase 2 submission to implement address changes. For Phase 2 submissions that are not based on a Phase 1 proposal, please fill in the information accordingly. Abstract [Abstract] The Abstract from your Phase 1 submission has been included in your Phase 2 template. You may need to update this text based on your final TAC allocation. Although we have attempted to convert frequently-used special LaTeX symbols, you should review this text carefully. Also, you may need to reformat some tabular information. If a Phase 2 submissions is not based on a Phase 1 proposal, please fill in missing information. General Instructions 15 Proposal Text Sections [Questions] These four sections are needed for STScI to execute your program properly. Not all questions will need to be answered by every observer, and note that the answers to these questions will be made public along with the rest of the RPS2 file. As with the Abstract, please review this text to make certain all special symbols have been correctly converted, and reformat tabular information if necessary. Description of Observations [Observing_Description] Provide a detailed description of your observing plans. Text from your Phase 1 proposal has been inserted, but it will need updating based on your final TAC allocation and on details worked out in Phase 2. Justification of Real-time observations and Special Scheduling Requirements [Real_Time_Justification] Provide an explanation for any real-time or special scheduling requirements, if they have been requested. Information from your Phase 1 proposal (Item 14) has been inserted, but it is possible that the text will need updating based on your final TAC allocation, to include the details worked out in Phase 2, and to remove any special calibration requirements (see below). Justification of Special Calibration Requirements [Calibration_Justification] Provide a justification for any special calibrations required for your program, if requested. Additional Comments [Additional_Comments] Provide any additional comments that you feel STScI needs to know in order to properly implement your program. Target Information [Fixed_Targets, Solar_System_Targets, Generic_Targets] Chapter 3: Fixed and Generic Targets [Generic _Targets] on page 23 and Chapter 4: Solar System Targets List [Solar_System_Targets] on page 59 describe how to fill out the Target Lists. 16 Chapter 2: The Basics of Phase 2 Proposals Visit Information [Visits] Chapter 5: Visits and Exposures on page 89 of this document describes how to fill out the Visit and Exposure Specifications. Instructions for submitting parallel observations are given in Chapter 6: Parallel Science Exposures on page 101, and the detailed, instrument-specific parameters are described in Part B: Supported Science Instruments on page 177. Data Distribution Information HST observers are now expected to retrieve their proprietary data via the web, using either the archive’s web retrieval form interface or StarView. It is possible to request “hard” media (either an 8 mm or a DAT tape) by using one of these tools. Observation summaries (previously called “paper products”) are also available, but only via the web. The Principal Investigator (or the Contact identified by the PI; see Investigators [Investigators] on page 14)will be informed automatically by e-mail when observational data and observation summaries are ready for retrieval. Anyone requiring access to proprietary data should be both a registered user and an authorized user of the HST archive. If you are only a registered user, you have access only to public data via your archive username and a password. The registration address you provide is where any hard media will be sent, but the address is not otherwise used. You can become a registered user by filling out a registration form on the World-Wide Web http://archive.stsci.edu/registration_form.html or by contacting the Archive Hotseat at archive@stsci.edu. Authorization additionally allows a PI and individuals selected by the PI to have access to the PI’s proprietary data and privileged web access to the observation summaries (which are PDF files). To become an authorized user, contact the Archive Hotseat. Authorization requests will be inspected very carefully. For this reason, authorization may take a little longer than simple registration. We strongly encourage PIs desiring this option to become registered and authorized well in advance of the execution of their program. Examples and General Advice 17 Examples and General Advice Acquisitions and Pointings Getting HST located and oriented properly lies at the heart of successful observations, especially when a small aperture is being used, and there are a number of ways to do that. The remarks here apply specifically to fixed targets, and mostly apply to the use of small apertures, although many of them can be applied to moving targets as well. For more information, see Target Position [Position] on page 34. First, you have to acquire an object successfully that is at or near the position at which the science observation will be made. The object to be acquired should meet these conditions: 1. It should be a point source or nearly enough to point-like that the centering algorithms can determine a precise centroid. 2. The object’s coordinates must be both precise and accurate and any proper motion must be known. This requirement boils down to the need for the object to fall within the search region at the time of the acquisition. For this to happen the coordinates must also be consistent with the Guide Star Catalog or they must fall within another system that can be related to the GSC. This is why the source of the acquired object’s coordinates are required. 3. The object must be neither too bright nor too faint for the instrument mode used. These conditions are described in the various Instrument Handbooks. The coordinates for the acquired object can be specified in several ways: • As explicit absolute celestial coordinates, i.e., RA and DEC. See Equatorial Coordinates on page 36. • As celestial coordinates relative to another nearby object, using RA-OFF and DEC-OFF or XI-OFF and ETA-OFF. See Positional Offsets on page 39. • As a REGION; see Region of Sky (Extended Targets) on page 41. Second, once the acquisition has been made, the telescope must be repositioned to the precise point desired. This step is unnecessary, of course, if the object acquired in the first instance is the object to be observed. Repositioning can be implicit or explicit. By an implicit offset is meant the case where a target such as “XX-OFFSET” is acquired with some ACQ mode, and then “XX” is observed via a science exposure. This often leads to confusion because no 18 Chapter 2: The Basics of Phase 2 Proposals specific motion of the telescope has been provided, but that motion is implied by specifying the separate targets with different coordinates. “XX-OFFSET” is specified for the acquisition because it is bright enough and point-like enough to be acquired successfully, but the coordinates specified by “XX” are what is to be observed. An explicit offset means using a Special Requirement such as POS TARG (see POSition TARGet <X-value>, <Y-value>) to move the telescope away from the position acquired. In this scheme, the position specified in the acquisition is placed at the fiducial point for the aperture requested (in general the geometric center of the aperture). The POS TARG then moves the telescope relative to that nominal position. Thus POS TARGs are not cumulative, and always refer back to the original acquired position. Examples Examples of HST observing programs are available as RPS2 formatted files on the STScI web pages. Many of the most popular observing techniques are represented. Once these files are downloaded, they may be easily edited for the specific targets and wavelengths desired. Start by going to the web page for the instrument you are using: For those observers who wish to try an observing sequence not shown there, help may be obtained from your Program Coordinator. Common Problems Incorrect Proposal Format The formats described in this document must be followed exactly, since the information in the forms is interpreted by computer software. Some items that warrant repetition are: • Target numbers and visit numbers must be unique. • Target names must be spelled exactly the same throughout the proposal. • The format for target positions must be followed to the letter. • The format for flux data must be followed. Only those defined in the instructions are acceptable. • The format for Optional Parameters and Special Requirements must be followed. Only those defined in these Instructions are acceptable. Examples and General Advice 19 • Observations which cannot be defined using the syntax in these Instructions may be described in Comments fields, but such comments should be used very sparingly, if at all, and their use may impede execution of a program. For more information on coordinates, see Getting Coordinates Coordinated on page 58. Imprecise Target Positions See the discussion of required position accuracies in Table 3.11: Required Coordinate Accuracies. The requirements are much more stringent than is typically the case for ground-based observations. Lack of Acquisition Exposures with Small Apertures When exposures are requested in very small apertures or fields of view (e.g., STIS), a separate acquisition exposure is generally required. Consideration of Limited Resources Proposers should be aware that several of the Special Requirements impose serious constraints on the scheduling system because they require the use of limited resources; for example, RT ANALYSIS requires real-time use of the TDRSS that is only available some of the time. Hence these Special Requirements should be requested only if they are absolutely necessary to achieve the scientific goals of a project. It is quite possible that some proposals will be impossible to schedule because of their resource requirements, rather than a lack of scientific merit. The limited-resource Special Requirements can force the planning system to schedule the observations at a less than optimal time. The use of limited-resource Special Requirements by many observers can reduce the overall efficiency with which the planning system can schedule the science program. For these reasons, these Special Requirements should only be used when necessary to achieve the science objectives of the program. The STScI will review the necessity for the Special Requirements and in some cases may suggest removing them, or using alternate methods to obtain the same goal. The following table summarizes the Special Requirements that involve seriously limited resources. The need for many of these Special Requirements must be justified in the Questions section of the RPS2 template. Note that several of these Special Requirements must have been justified in the Phase 1 Proposal in order to be used legitimately in Phase 2; those are CVZ, SHADOW, and Targets of Opportunity. 20 Chapter 2: The Basics of Phase 2 Proposals Table 2.1: Limited-Resource Special Requirements Limited Resource Reason for constraint ON HOLD [FOR <visit-list>] Require special handling. RT ANALYSIS, REQuires UPLINK Requires real-time TDRSS links, which are difficult to schedule and may be withdrawn at last moment. ORIENTation <angle1> TO <angle2>, SAME ORIENTation AS <visit> A specific orientation can be available for as little as a one-week period every six months. SHADOW, LOW-SKY, CVZ Available for only a fraction of orbits. AFTER <date>, BETWEEN <date1> AND <date2>, BEFORE <date>, SEQuence <visit-list> WITHIN <time>, SEQuence <exposure-list> NON-INTerruptible, PHASE <number1> TO <number2>, NO SPLIT Constrain scheduling opportunities. Can be mutually incompatible. Proposal Template Your proposal template should include the following and in the order given. Optional blocks are in square brackets ([]). The use of colons is required in the form given. Note that at least one of the three target types (Fixed, Solar System, or Generic) must be present unless the proposal contains only internal or predefined pointings. Proposal_Information Title: Proposal_Category: Cycle: [Avail_Ok:] [Parallel_Information Parallel_Pointing_Tolerance] Investigators PI_Name: PI_Institution: Proposal Template [CoI_Name: CoI_Institution: [Contact:]] Abstract: Questions: Observing_Description: [Real_Time_Justification:] [Calibration_Justification:] [Additional_Comments:] [Fixed_Targets Target_Number: Target_Name: [Alternate_Names:] Description: Position: Equinox: Coordinate_Source: [RV_or_Z:] [RA_PM:] [Dec_PM:] [Epoch:] [Annual_Parallax:] Flux: [Comments:]] [Solar_System_Targets Target_Number: Target_Name: Description: Level_1: [Level_2:] [Level_3:] [Window:] [Ephem_Uncert:] [Acq_Uncert:] Flux: [Comments:]] 21 22 Chapter 2: The Basics of Phase 2 Proposals [Generic_Targets Target_Number: Target_Name: Description: Criteria: Flux: [Comments:]] Visits Visit_Number: [Visit_Priority:] [Visit_Requirements:] [On_Hold_Comments:] [Visit_Comments:] Exposure_Number: Target_Name: Config: Opmode: Aperture: Sp_Element: [Wavelength:] [Optional_Parameters:] Number_Of_Iterations: Time_Per_Exposure: [Special_Requirements:] [Comments:] CHAPTER 3: Fixed and Generic Targets [Generic _Targets] For an explanation of this engineering-only version, see Special Note to Engineering Version Users in Chapter 1: About This Document on page 3. In this Chapter . . . Target Number [Target_Number] / 25 Target Name [Target_Name and Alternate_Names] / 25 Target Description [Description] / 29 Target Position [Position] / 34 Equinox for Coordinates [Equinox] / 45 Source of Specified Coordinates [Coordinate_Source] / 45 Radial Velocity or Redshift [RV_or_Z] / 47 Is Proper Motion or Parallax Relevant? / 48 Flux Data [Flux] / 49 Bright-Object Constraints / 53 Comments [Comments] / 54 Generic Targets List [Generic_Targets] / 55 23 24 Chapter 3: Fixed and Generic Targets [Generic _Targets] Tables and Figures Table 3.1: Designations of Special Targets Table 3.2: Target Categories Table 3.3: Descriptive Keywords for STAR and EXT-STAR Table 3.4: Descriptive Keywords for STELLAR CLUSTER and EXT-CLUSTER Table 3.5: Descriptive Keywords for GALAXY Table 3.6: Descriptive Keywords for CLUSTER OF GALAXIES Table 3.7: Descriptive Keywords for ISM and EXT-MEDIUM Table 3.8: Descriptive Keywords for UNIDENTIFIED Table 3.9: Descriptive Keywords for CALIBRATION Table 3.10: Discrete Features and Descriptors for All Categories Table 3.11: Required Coordinate Accuracies Table 3.12: Required Coordinate Accuracies for NICMOS (Restricted) Table 3.13: Formats for Specification of Target Flux Data Table 3.14: Bright-Object Constraints Table 3.15: Bright-Object Constraints for NICMOS (Restricted) The use of the RPS2 “FIXED_TARGETS” and “GENERIC_TARGETS” blocks are described in this chapter. To make the presentation of this material more concise, the section on solar system targets has been made into a separate chapter; see Chapter 4: Solar System Targets List [Solar_System_Targets] on page 59. The Target List tells us where you wish to point HST and so must be filled out with care, precision, and accuracy. The Target List also provides the information that defines and describe the targets, and which was used to determine exposure times. Three different kinds of Target Lists exist for the following three classes of targets, but only the Target List(s) required for your proposal need be submitted: • Fixed targets (all targets outside the solar system whose positions can be defined by specific celestial coordinates); • Solar-system targets (all moving targets); Target Number [Target_Number] 25 • Generic targets (targets defined by certain properties, rather than by specific coordinates). In this chapter, each heading has a description followed by a keyword in square brackets (e.g., Target_Number). The keyword must be used in your RPS2 form. Elsewhere, items in boldface (e.g., RA-OFF) show words or phrases that are to be used directly as RPS2 entries. Items in brackets (e.g., <value>) show entries you are to provide. Parameters listed in square brackets (e.g., [A1 = <value>]) are optional, whereas those not in square brackets are required. Target Number [Target_Number] Each target that will be observed must be assigned its own unique number. Target numbers must be positive and monotonically increasing (but not necessarily consecutive) integers. A different target must be defined whenever different coordinates or a different target description are required. Separate targets should be defined and listed if you plan to take observations at several points within an extended object. For example, if you were to take spectra at three different locations in the Crab Nebula, each point must have its own target number, name, and coordinates, such as CRAB1, CRAB2, and CRAB3. If more than one type of Target List is used (such as both fixed and generic target lists), continue with the same numbering scheme used on the preceding Target List but start with a target number which is larger than the last target number on the preceding list. All target numbers and names within a proposal must be unique (within that proposal). Target Name [Target_Name and Alternate_Names] Target names are used to provide unique designations for the targets that will be used throughout the proposal. These names will also be used to designate targets in the HST data archive. Prospective proposers and archival researchers will use these names to determine whether HST has observed a particular object. This facility will be most useful if consistent naming conventions are used. The following conventions must be followed in naming targets: 26 Chapter 3: Fixed and Generic Targets [Generic _Targets] • A new target name must be defined for each (celestial) target. For example, for several pointings within a galaxy, one might define target names such as NGC4486-NUC, NGC4486-JET, NGC4486-POS1, and NGC4486-POS2. • The maximum allowable length of a target name is 30 characters. • No blanks are permitted in target names. Blanks between a letter and a numeral must be suppressed (e.g., HD140283, NGC4378), but a hyphen (and not an underscore) must replace blanks between two letters or two numerals (e.g., ALPHA-CEN, NGC224-0040+4058). Also, a hyphen should be used where required for clarity (e.g., NGC4486-POS1). • Only letters, numerals, hyphens, periods (.), and + or – are allowed in target names; other punctuation is not permitted (e.g., BARNARDS-STAR is valid, but BARNARD’S-STAR is not). Greek letters must be spelled out (e.g., ALPHA-ORI). Letters may be upper-case or lower-case, but will always be treated as if they are upper case (e.g. Alpha-Cen will be treated as if written ALPHA-CEN). • Degree signs must be represented by an upper-case “D” (e.g., CD-42°14462 becomes CD-42D14462). • Some special target names are reserved for calibrations and other purposes and may not be used for external pointings; see Table 3.1: Designations of Special Targets. Whenever possible, two types of designations should be provided for each target. The first will be a “catalog name” (for example, HD124897), and the second will be at most two “common names” (e.g., ALPHA-BOO, ARCTURUS). The “catalog name” is entered in Target_Name and the “common names” are entered in Alternate_Names. Only the catalog name is used when the target name is repeated in the Visit and Exposure Specifications. If the target is in the STScI Guide Star Catalog (GSC), the GSC name should be included as one of the common names (e.g., GSC5637-12345). Catalog Name The preferred order for catalogs to be used for the designation of various classes of objects is provided below. It is arranged in order of decreasing preference. If a target is not contained in these catalogs, other catalog designations may be used (e.g., 4U X-ray catalog designation, Villanova white-dwarf catalog Target Name [Target_Name and Alternate_Names] 27 number, etc.). The use of positional catalogs (SAO, Boss, GC, AGK3, FK4, etc.) is discouraged. For uncataloged targets, see Uncataloged Targets on page 28. Stars 1. Henry Draper Catalog number (e.g., HD140283)is preferred. HDE numbers are discouraged, except in the Magellanic Clouds. 2. Durchmusterung number (BD, CD, or CPD). In the southern hemisphere, adopt the convention of using CD north of –52 degrees and CPD south of there (e.g., BD+30D3639, CD-42D14462, CPD-65D7691). 3. General Catalog of Variable Stars designation, if one exists (e.g., RR-LYR, SS-CYG). 4. AFGL designation. 5. IRC designation. 6. IRAS designation. Star Clusters and Nebulae 1. New General Catalog (NGC) number (e.g., NGC6397, NGC7027). 2. Index Catalog (IC) number (e.g., IC418). 3. For planetary nebulae for which you do not have an NGC or IC designation, the Perek-Kohoutek designation (e.g., PK208+33D1) may be used. 4. For H II regions for which you do not have an NGC or IC designation, the Sharpless catalog number (e.g., S106) may be used. 5. For IR nebulae, AFGL designation. Galaxies and Clusters of Galaxies 1. NGC number (e.g., NGC4536). 2. IRAS designation. 3. IC number (e.g., IC724). 4. Uppsala Catalog number, only if an NGC or IC number is not available (e.g., UGC11810). 5. For clusters of galaxies, the Abell catalog number, but only if an NGC or IC number is not available (e.g., ABELL2029). 28 Chapter 3: Fixed and Generic Targets [Generic _Targets] Quasars and Active Galaxies 1. The name defined in the compilation by Veron-Cetty and Veron (ESO Report No. 7, 1989) must be used (e.g., 3C273). Uncataloged Targets Objects that have not been cataloged or named must be assigned one of the following designations: 1. Isolated objects must be designated by a code name (the allowed codes are STAR, NEB, GAL, STAR-CLUS, GAL-CLUS, QSO, SKY, FIELD, and OBJ), followed by a hyphen and the object’s J2000 equatorial coordinates, if possible, rounded to seconds of time and seconds of arc (e.g., for a star at J2000 coordinates RA = 1H 34M 28S, DEC = –15D 31' 38", the designation would be STAR-013428-153138). 2. Uncataloged objects within star clusters, nebulae, or galaxies must be designated by the name of the parent body followed by a hyphen and the rounded J2000 coordinates, if possible, of the object (e.g., for a target within NGC 224 with J2000 coordinates RA = 0H 40M 12S, DEC = +40D 58' 48", the designation would be NGC224-004012+405848). 3. Positions within nebulae or galaxies may also be designated by the name of the parent object followed by a hyphen and a qualifier. The qualifier should be brief, but informative (e.g., the jet in NGC 4486 could be designated NGC4486-JET). Other examples are: NGC5139-ROA24, LMC-R136A, ABELL30-CENTRAL-STAR, NGC205-NUC. Common Names In addition to the catalog name, a target should be assigned at most two “common names,” or aliases, if they exist. Examples of common names are the following: 1. Stars: The Bayer (Greek-letter) designation or Flamsteed number with standard three-letter constellation abbreviation (e.g., ZETA-CAP, 22VUL, OMICRON2-ERI-B); the Bright Star Catalog number (e.g., HR5270); other names, if they exist (e.g., CYG-X1, BARNARDS-STAR, PROXIMA-CEN). 2. Star clusters, nebulae, galaxies, and clusters of galaxies: Commonly used names (e.g., HYADES, OMEGA-CEN, CRAB-NEBULA, ABELL63, COMA-CLUSTER); Messier numbers (e.g., M13, M31, M67). Target Description [Description] 29 Special Targets The names of certain types of targets must be designated by appending a code to the target name. For example, -CALIB should be appended to the name of a target that is being observed only as a calibration standard for other observations. These designations will assist in planning of the observing schedule. The three possible codes are listed in Table 3.1. Table 3.1: Designations of Special Targets Target Type Code Description External calibration target -CALIB An astronomical target used for calibration (e.g., BD+28D4211-CALIB). Internal calibration sources (e.g., WAVE) and calibrations using the Earth must not be included in the Target List. Astrometric reference star -REF Stars used to determine astrometric positions of other targets (e.g., HD20731-01-REF would designate reference star 01 near HD 20731). Note that the “parallax star” (the target whose position is being measured) may not have a –REF suffix. Offset acquisition target -OFFSET A target that will be used for an offset acquisition; it is the object that will be acquired first, from which an offset will be applied to move to the target of interest (e.g., 3C273-OFFSET). Two separate exposures must be defined on the Visit and Exposure Specifications; an acquisition of the -OFFSET target, and a science exposure of the (target of interest) program target. The location of the latter target may be specified either by equatorial coordinates or by an offset (see Target Position [Position] on page 34). For example: to observe the JET in 3C273, first acquire “stellar-like” source 3C273-OFFSET, then offset to program target 3C273-JET. Special designations These are reserved designations and may not be used as the names of external pointing in a target list: ANTI-SUN, ANY, BIAS, CCDFLAT, DARK, EARTH-CALIB, INTFLAT, KSPOTS, NONE, ORBIT-POLE, ORBIT-POLE-NORTH, ORBIT-POLE-SOUTH, UVFLAT, VISFLAT, WAVE Target Description [Description] A target description must be provided for each target. The Target Description will be one of the key fields used by archival researchers in 30 Chapter 3: Fixed and Generic Targets [Generic _Targets] searching through the HST data archive; thus it is extremely important that the information be filled out completely and accurately for each target. Each target must be assigned a single primary category from Table 3.2, and at least one descriptive keyword, chosen from the appropriate Table 3.3 through Table 3.9 (see Table 3.2 for which table is appropriate for each category). The discrete features and descriptors in Table 3.10 may be used as descriptive keywords for any category. A maximum of five descriptive keywords may be specified. It is possible, but not required, to specify a second category for a target, followed by one to five descriptive keywords from the appropriate tables, as described for the primary category. Whether one or two categories are used, all values must be separated from each other by commas. For example, suppose the STAR category is chosen with the descriptive keywords Polar and Interacting Binary. This target description would be specified as STAR, Polar, Interacting Binary. The categories in Table 3.2, and some of the descriptive keywords in Table 3.3 through Table 3.10, are followed by explanatory text in parentheses. This text is provided only for explanatory purposes and is not part of the category or keyword itself. Only the non-parenthesized portion, which appears in bold in the tables, should be entered into the RPS2 file. Table 3.2: Target Categories Category Descriptive Keywords Discrete Features and Descriptors SOLAR SYSTEM (Solar System Object) Chapter 4: Solar System Targets List [Solar_System_Targets] on page 59 STAR (Galactic Stellar Object) Table 3.3 EXT-STAR (Star in an External Galaxy) Table 3.3 STELLAR CLUSTER (Galactic Star Cluster, Group, or Association) Table 3.4 EXT-CLUSTER (Star Cluster in an External Galaxy) Table 3.4 GALAXY (Galaxy or AGN) Table 3.5 CLUSTER OF GALAXIES (Galaxy Groupings, Clusters, Large-scale Structure) Table 3.6 ISM (Interstellar Medium of the Galaxy) Table 3.7 EXT-MEDIUM (Interstellar Medium of an External Galaxy) Table 3.7 UNIDENTIFIED (Unidentified Objects) Table 3.8 CALIBRATION (Calibration Observations) Table 3.9 See Table 3.10 Target Description [Description] Table 3.3: Descriptive Keywords for STAR and EXT-STAR Brown Dwarf AGB Star Herbig Ae/Be Wolf Rayet Post-AGB Star Horizontal Branch Star Wolf Rayet – WC Composite Spectral Type Interacting Binary Wolf Rayet – WN F0-F2 X-ray Novae Main Sequence O F3-F9 X-ray Burster Giant O FP X-ray Transient Supergiant O Late-type Degenerate LMXB (Low Mass X-ray Binary) OE G V-IV Gamma Ray Burster OF G III-I MXB (Massive X-ray Binary) SDO K V-IV RS CVn Star WDO K III-I W UMa Star B0-B2 V-IV M V-IV Beta Lyrae Star B3-B5 V-IV M III-I Algol System B6-B9.5 V-IV S Star Barium Star B0-B2 III-I Carbon Star Blue Straggler B3-B5 III-I Long Period Variable Neutron Star B6-B9.5 III-I Irregular Variable Pulsar BE Regular Variable Binary Pulsar BP Luminous Blue Variable FK Comae Star SDB Dwarf Nova Pulsating Variable DB Classical Nova PG1159 Star DA Nova-like ZZ Ceti Star DC Recurrent Nova Cepheid DZ Polar (AM Her Star) Supernova A0-A3 V-IV Intermediate Polar (DQ Her Star) Supernova Type Ia A4-A9 V-IV Symbiotic Star Supernova Type Ib A0-A3 III-I T Tauri Star Supernova Type II A4-A9 III-I FU Orionis Star RR Lyrae Star AE Shell Star Planetary Nebula Central Star AM Eta Carinae Star Emission Line Star AP YSO 31 32 Chapter 3: Fixed and Generic Targets [Generic _Targets] Table 3.4: Descriptive Keywords for STELLAR CLUSTER and EXT-CLUSTER Globular Cluster OB Association Open Cluster T Association Table 3.5: Descriptive Keywords for GALAXY Spiral (Spiral Galaxy) Quasar (Radio Loud) Lenticular (Lenticular Galaxy) Radio Galaxy Elliptical (Elliptical Galaxy; Not A Dwarf Elliptical) BL Lac (BL Lac or BLAZAR) Dwarf Elliptical Liner Magellanic Irregular Starburst Amorphous Irregular Ultraluminous IR Gal Dwarf Compact (Dwarf Compact/HII Galaxy) Interacting Galaxy Dwarf Spheroidal Lyman Alpha Cloud BCM (Brightest Cluster Member) Protogalaxy BGM (Brightest Group Member) Gravitational Lens LSB (Low Surface Brightness/HI Rich Galaxy) Einstein Ring Seyfert High Redshift Galaxy (z > 0.5) QSO (Radio Quiet) Table 3.6: Descriptive Keywords for CLUSTER OF GALAXIES Supercluster Interacting Galaxy Void BCM (Brightest Cluster Member) Group BGM (Brightest Group Member) Rich Cluster Gravitational Lens Poor Cluster Einstein Ring High Redshift Cluster (z > 0.5) Blank Sky Galaxy Pair Target Description [Description] 33 Table 3.7: Descriptive Keywords for ISM and EXT-MEDIUM Description Herbig-Haro Object Cometary Nebula Planetary Nebula Molecular Cloud HII Region Bipolar Outflow Reflection Nebula Absorption Line System Dark Cloud Absorption Line System – Galactic SNR (Supernova Remnant) Absorption Line System – Extragalactic Ring Nebula Damped Lyman Alpha Cloud (Extragalactic) HI Cloud Coronal Gas (105–106 K) High Velocity Cloud Hot Gas (107–108 K) Intermediate Velocity Cloud IGM IRAS Cirrus ICM Table 3.8: Descriptive Keywords for UNIDENTIFIED Radio Emitter Ultraviolet Emitter Blank Field Low Latitude Field Infrared Emitter X-ray Emitter Parallel Field Optical Emitter Gamma Ray Emitter High Latitude Field Table 3.9: Descriptive Keywords for CALIBRATION Astrometric Narrow Band Filter Calibration Target Acquisition Test Photometric FGS Stability Detector Sensitivity Test Wavelength Quantum Efficiency Test Focus Test Point Spread Function Pointing and Jitter Test Spacecraft Glow Occulting Finger Location Raster & Step/Dwell Scan Verification Occultation Mode Test Ion Spatial Distortion Test Throughput Test Taled Polarimetry Echelle Blaze Function Scattered Light Test Aperture Location Virtual Pointing Sky Background Detector Linearity Test FGS Transfer Function Test Instrument Sensitivity Test Carrousel Stability Test Shutter Control Test 34 Chapter 3: Fixed and Generic Targets [Generic _Targets] Table 3.10: Discrete Features and Descriptors for All Categories Corona Disk BLR (Broad Line Region) Ring Bulge NLR (Narrow Line Region) Ansae Polar Ring Filament Protoplanetary Disk Dust Lane Ejecta Wind Spiral Arm Knot Accretion Disk Shell Star Forming Region Jet Tidal Tail Shock Front Lobe Bar Ionization Front Hotspot Multiple Nuclei Conduction Front Nucleus Cooling Flow Undesignated Halo Emission Line Nebula Target Position [Position] A position is required for each fixed target. The position may be expressed in any one of three different ways: • By specifying the equatorial coordinates (RA and DEC) of the target; • By specifying a positional offset from another target; or • By specifying a region (area) of the sky. It is also possible to specify that the coordinates were obtained using the Guide Star Selection System (GSSS; see Determining Coordinates in the Guide Star Selection System (GSSS) Reference System on page 42), or that they are currently uncertain or unknown, and that more accurate coordinates will be provided by the observer after an early acquisition exposure is taken, or in real time during the HST observations. Required Accuracies of Target Positions The HST Scientific Instruments (SIs) typically have very small apertures and fields of view. Target-acquisition apertures for several of the SIs are only a few seconds of arc in size. Since the HST has no analog to the video acquisition cameras common on many ground-based telescopes, it is essential to have accurate coordinates for targets. In many cases targets will be placed in the final observing aperture after a sequence of target-acquisition observations. This will only work, however, if the target Target Position [Position] 35 coordinates are sufficiently accurate and precise to place the target in the first of these acquisition apertures. HST uses two guide stars to stabilize the pointing of the telescope and to place the target in the desired aperture. The fundamental problem, then, is to determine the position of the target relative to the guide stars in the surrounding area with sufficient accuracy to place the target in the aperture. The specific pair of guide stars to be used cannot be determined in advance of the observation; several possible pairs will often be available for each target. The guide stars are chosen from the Guide Star Catalog (GSC). The uncertainty of the relative positions of a group of potential guide stars in the GSC is 0.33 arcsec (1 sigma) in the north and about 0.5 arcsec in the south. The accuracies of positions typically needed for target acquisition with each of the SIs are shown in Table 3.11; these are predicated upon the positions being in the coordinate system of GSC, which is based upon the AGK3 and SAO reference systems. Note that several of the SIs have multiple acquisition apertures of different sizes that may be used. Be sure when selecting acquisition apertures to keep the coordinate uncertainties in mind. Furthermore, be sure to provide 1 sigma uncertainties with your positions so that STScI may check the appropriateness of your acquisition exposures. Inaccurate target coordinates can result in failed target acquisitions and can therefore waste valuable HST observing time. As indicated in Table 3.11, it is the observer’s responsibility to provide accurate coordinates in all cases, but in particular they must be in the GSC reference frame when using STIS, and NICMOS with the NIC1 and NIC2 detectors. Please contact your PC if you need additional information. Although GSC frame-based coordinates are not required for FGS and WFPC2 observations, it is still prudent to check the accuracy of your coordinates. All observers will be provided target confirmation charts by their PC to help them verify the target coordinates in the GSC reference frame. The Principal Investigator of a program is responsible for ensuring that target coordinates are accurate, both at the time of program submission, and later when target confirmation charts are provided. The following address has pertinent information on target confirmation charts: Note: HST proposals executed before July 1991, as well as engineering proposals of type OV, SV, SMOV, and CAL, should not be used to derive target coordinates. Coordinates from such proposals may be unreliable owing to poor calibration and/or engineering-related pointing changes made during the observations. 36 Chapter 3: Fixed and Generic Targets [Generic _Targets] Table 3.11: Required Coordinate Accuracies Instrument Configuration Accuracy Required (1 sigma, arcsec) GSC Coordinates Required? WFPC2 (WFC) 10 No WFPC2 (PC) 5 No STIS 1 Yes FGS 1 No Table 3.12: Required Coordinate Accuracies for NICMOS (Restricted) Instrument Configuration Accuracy Required (1 sigma, arcsec) GSC Coordinates Required? NIC1a (Restricted) 3 Yes NIC2 (2) (Restricted) 5 Yes NIC3 (2) (Restricted) 10 No a. If multiple NICMOS detectors are being used in parallel, the primary detector (the detector used for the exposures in the <primary-exp-list> of the PARallel WITH Special Requirement; see PARallel <parallel-exp-list> WITH <primary-exp-list>) determines the required coordinate accuracy for the observation and whether GSC frame-based coordinates are required. Equatorial Coordinates If you specify the target position directly in terms of equatorial coordinates (as opposed to specifying an offset or a region), then the right ascension and declination and their uncertainties are required, using the following format: RA = <value> +/– <uncertainty>, DEC = <value> +/– <uncertainty> • The comma following the right-ascension uncertainty is required. • The uncertainties represent the accuracy (1 sigma) of the target coordinates, not the region within which a target could be observed (e.g., for a sky measurement). See Region of Sky (Extended Targets) on page 41 for instructions on how to designate regions as targets. • The right-ascension value must be expressed either in hours (H), minutes (M), and seconds (S) of time; or in decimal degrees (D). For example, RA = 108.14375D and RA = 7H 12M 34.5S are equivalent. Target Position [Position] 37 • The declination value must be expressed either in degrees (D), minutes ('), and seconds (") of arc; or in decimal degrees (D). Thus DEC = -12D 55M 33.3S and DEC = -12.92592D are equivalent. • Units must be provided for both a value and its uncertainty. The uncertainty must be expressed in one and only one of the units used to express the related RA and/or DEC, with the additional units of minutes (') of arc or seconds (") of arc being allowed for right ascension. (In other words, the RA may be expressed as a combination of three units [H, M, S], but its uncertainty must be in terms of a single unit such as S or ".) To clarify: Quantity and units specified Acceptable units for uncertainty RA: H-M-S timemin, timesec, arcmin, arcsec RA: Degrees degrees DEC: D-M-S degrees, arcmin, arcsec DEC: Degrees degrees An example: RA = 12H 7M 13.33S +/– 0.15S, DEC = +27D 3' 8.0" +/– 0.1" and RA = 181.80554D +/- 0.00063D, DEC = +27.05222D +/- 0.00003D are equivalent. Note: If the sign of the declination is not indicated, a positive declination is assumed, but we urge you to always include the sign as a way of reducing errors. The following text is made Engineering until the issue of coordinate uncertainties is resolved. If you specify the target position directly in terms of equatorial coordinates (as opposed to specifying an offset or a region), then the right ascension and declination are required, using the following format: RA = <value>[ +/– <uncertainty>], DEC = <value>[ +/– <uncertainty>] • The comma following the right-ascension is required. • The right-ascension value must be expressed either in hours (H), minutes (M), and seconds (S) of time; or in decimal degrees (D). For example, RA = 108.14375D and RA = 7H 12M 34.5S are equivalent. 38 Chapter 3: Fixed and Generic Targets [Generic _Targets] • The declination value must be expressed either in degrees (D), minutes ('), and seconds (") of arc; or in decimal degrees (D). Thus DEC = -12D 55M 33.3S and DEC = -12.92592D are equivalent. • The uncertainties, if specified, represent the accuracy (1 sigma) of the target coordinates, not the region within which a target could be observed (e.g., for a sky measurement). See Region of Sky (Extended Targets) on page 41 for instructions on how to designate regions as targets. • Uncertainties for these values are no longer required, but units must be provided for both a value and its uncertainty when both are listed. The uncertainty should be provided if it is larger than about 2 arcsec; it is used in computing slew times for some Special Requirements that reuse positional offsets from a previous visit. If provided, the uncertainty must be expressed in one and only one of the units used to express the related RA and/or DEC, with the additional units of minutes (') of arc or seconds (") of arc being allowed for right ascension. (In other words, the RA may be expressed as a combination of three units [H, M, S], but its uncertainty must be in terms of a single unit such as S or ".) To clarify: Quantity and units specified Acceptable units for uncertainty RA: H-M-S timemin, timesec, arcmin, arcsec RA: Degrees degrees DEC: D-M-S degrees, arcmin, arcsec DEC: Degrees degrees An example: RA = 12H 7M 13.33S +/– 0.15S, DEC = +27D 3' 8.0" +/– 0.1" and RA = 181.80554D +/- 0.00063D, DEC = +27.05222D +/- 0.00003D are equivalent. Target Position [Position] 39 IMPORTANT: Both SAVE OFFSET and USE OFFSET rely on accurate coordinate uncertainties in order to calculate slew times properly. Unspecified target coordinate uncertainties may lead to a failure in execution of USE OFFSET. Program Coordinators should ensure that target coordinate uncertainties have been provided by the observer and that they are accurate. Note: If the sign of the declination is not indicated, a positive declination is assumed, but we urge you to always include the sign as a way of reducing errors. Positional Offsets The position of a target may alternatively be specified as an offset from a reference target. It is possible to specify offsets in equatorial coordinates, in rectangular coordinates, or in polar coordinates, all of which have their origin at the reference target. Note, however, that offsets larger than 30 arcsec may complicate the target acquisition procedure. If larger offsets are desired, please contact your Program Coordinator. Equatorial and rectangular offsets are always in the sense offset = target-coordinates minus offset-reference-coordinates, while a polar offset is expressed as an angular separation and position angle of a line drawn from the offset reference target to the target. As with other similar quantities, we urge you to include the sign of the offset, even when it is positive, as a means of removing ambiguity. Note that in the examples below, FROM 6, 3, and 4 are the target numbers which contain the equatorial coordinates of the reference targets, and that the reference-target names have –OFFSET appended (see Table 3.1). Positional offsets are only a convenient method of specifying target coordinates, and do not automatically imply a particular method of target acquisition; observers must explicitly specify any target acquisitions on the Visit and Exposure Specifications via Special Requirements (see Chapter 7: Special Requirements [Visit_Requirements and Special_Requirements] on page 111). 40 Chapter 3: Fixed and Generic Targets [Generic _Targets] Warning: If your object has significant proper motion no correction may be applied. See Is Proper Motion or Parallax Relevant? on page 48, where it notes that the proper motion for the target is taken to be the same as for the offset object. As with coordinates, uncertainties are no longer required. RPS2 will insert values of zero if you do not provide an uncertainty. Uncertainties matter only in special cases that involve reusing offsets from previous visits, and even then the uncertainty is not ordinarily of significance. 1. The format for the specification of an offset as a difference in EQUATORIAL coordinates is: RA-OFF =<value> +/– <uncertainty>, DEC-OFF = <value> +/– <uncertainty>, FROM <target number> Note the uncertainties and the commas separating the three items. The value for RA-OFF may be in units of seconds (S) of time or in decimal degrees (D), and the value for DEC-OFF may be in units of arcmin (') or arcsec ("), or in decimal degrees (D). The uncertainty must be expressed in one and only one of the units used to express the related RA and/or DEC. In the following example, a target’s right ascension is 1.1 seconds of time greater than, and its declination is 10 arcsec less than, the right ascension and declination of target number 6: RA–OFF = +1.1S +/– 0.2S, DEC–OFF = –10" +/– 1", FROM 6 2. Offsets in RECTANGULAR coordinates are interpreted as displacements in the tangent plane whose origin is located at the reference target. For displacements of less than about one degree, they may be interpreted as the offsets that are measured on a photographic plate, without making errors larger than about 0.5 arcsec. The format for the specification of an offset in rectangular coordinates is: XI-OFF = <value> +/- <uncertainty>, ETA-OFF = <value> +/<uncertainty>, FROM <target number> Note: North and east displacements are considered positive (+), south and west are negative (–). The values of XI-OFF and ETA-OFF are required to both be expressed in arcmin (') or arcsec ("), and the uncertainties must be expressed in the same units (in other words, all four angular quantities must be in the same units). In the following example, a target has been measured on a sky-survey plate, with a scale of 67 Target Position [Position] 41 arcsec/mm, to lie 0.5 mm west of, and 1 mm north of, target number 3, with an accuracy of 1 arcsec: XI–OFF = –33" +/– 1", ETA–OFF = +67" +/– 1", FROM 3 3. The format for a POLAR offset specification is: R = <value>, PA = <value>, FROM <target number> Note that uncertainties must not be included in this type of specification. The separation is expressed in units of minutes (') or seconds (") of arc. The position angle of the target with respect to the reference target is measured east of north, and the unit of measurement (degrees) is required. In the following example, a target lies 10 arcsec from target number 4, at a position angle, measured at target 4 from north through east, of 60 degrees: R = 10", PA = 60D, FROM 4 Region of Sky (Extended Targets) Sometimes it is necessary to define a region of sky rather than a specific point. Examples are extended targets (such as emission nebulae and galaxies) and blank-sky regions for background measurements (if it is acceptable to make the observation anywhere within a region). It is possible to specify rectangular or circular regions. An Equinox value should be specified with the region coordinates (see Equinox for Coordinates [Equinox] on page 45). The units used for regions should be used in the same way as for coordinates; see Equatorial Coordinates on page 36. Rectangular Region For a rectangular region, the format for equatorial coordinates must be used, followed by a comma and the word REGION; the values following +/– will then be interpreted as one-half the lengths of the sides of the rectangular area, rather than as uncertainties in the coordinates. In the following example, a region 4 arcmin wide in right ascension by 2 arcmin high in declination is specified: RA = 3H 51M 27S +/– 2', DEC = –37D 13' 25" +/– 1', REGION Circular Region If it is desired to specify a circular region, REGION must be followed by another comma and the radius of the region in the format R = <radius>; in this case, no uncertainties should be attached to the RA and DEC. Here is an example of a circular region with a radius of 2 arcmin: 42 Chapter 3: Fixed and Generic Targets [Generic _Targets] RA = 3H 51M 27S, DEC = –37D 13' 25", REGION, R = 2' Note that the units of R must be specified. Determining Coordinates in the Guide Star Selection System (GSSS) Reference System The HST reference frame is defined by the HST Guide Star Catalog (GSC) that STScI has created. For observations that require accurate coordinates, such as those listed as “GSC Coordinates Required” in Table 3.11, it is vital that you provide positions derived in the same reference frame as the original GSC plate material. Access to the GSC, as well as lightly compressed versions of the plates used to construct the GSC, is available on the CASB WWW server. Begin at http://www-gsss.stsci.edu/support/phase2.html and follow the links under “General Guidelines.” Coordinates produced using these facilities will be in the same reference frame as the GSC. Here are some more detailed guidelines for different categories of brightness and type: 1. Stars with m(V) between about 9 and 14 (at high galactic latitude) or between about 9 and 13 (at low galactic latitude): Most of these are contained in the GSC. You can retrieve GSC coordinates using a form available on the CASB Web server listed above. When you have the GSC coordinates, enter them in the Position field of the Target List, followed by the plate identification number (not the region number) from the GSC, using the format PLATE–ID = <plate identifier>. This identifies the target coordinates as coming from the GSC. Also enter the GSC name as a target alias in Alternate_Names. An example: RA = 12H 13M 14.27S +/– 0.3", DEC = –13D 11' 03.3" +/– 0.3", PLATE–ID=00TB For stars brighter than about m(V) = 9, coordinates from the Hipparcos Input Catalogue have been added to the GSC; these coordinates can be recognized as having a plate designation of +056. Enter the GSC name as a target alias, but do not include the PLATE–ID for coordinates derived from the Hipparcos Input Catalogue (but do indicate in the target-level Coordinate_Source field that the coordinates are from Hipparcos). Note that coordinates from the Hipparcos Output Catalog are on a different system from the GSC; but the differences are negligible in almost all instances. Target Position [Position] 2. 43 Stars fainter than about m(V) = 13 – 14, and extended sources: The plate material that was used to construct the GSC will generally allow identification of targets to magnitudes of V = 19 in the northern- and J = 22 in the southern hemisphere. Use the facility and instructions available on the CASB Web server listed above to determine coordinates of targets on the GSC plates. Once coordinates have been obtained, Position should again contain the plate ID from GSC, using the PLATE–ID = <number> format. Contact your Program Coordinator if you need assistance. 3. Stars fainter than about m(V) = 13 – 14, and extended sources (for which special plates or ground-based CCD images were obtained): You must transfer the GSC reference frame to your special plates or CCD images. You will need about ten stars from GSC as your reference stars when carrying out plate reductions. Enter the coordinates in Position, again with the PLATE–ID = <number> format, to indicate which GS plate provided the coordinates used for the plate reduction. As part of preparing your observations, your Program Coordinator will provide, as a final check that the coordinates are correct, a Confirmation Chart showing the target coordinates (as entered in the proposal) overlaid on the field from the plate material used to construct the Guide Star Catalog. You are responsible for verifying that the coordinates are correct. (See Required Accuracies of Target Positions on page 34.) A Caution on Astrometry Prepared from STScI Plate Scans Note that the set of plates used to construct the GSC is NOT the same one that is contained in the 102-volume set of CD ROMs distributed as the Digitized Sky Survey (DSS-I) and that is available elsewhere at the stsci.edu Web site. The DSS-I uses the 1950 epoch POSS-E plates for the north, whereas the GSC in the north is based on the 1982 epoch Palomar Quick V. Similarly, in a few cases, the southern plates used in the GSC are not the ones in the DSS-I. HST users may use the DSS-I CD ROMs to prepare their Phase 2 submissions only if they verify that the DSS-I plates are the same as those used in the GSC, i.e., the plate ID field must be identical. Prohibition on the Use of GSC Version 1.2 Preliminary access to an improved (astrometrically recalibrated) GSC, version 1.2, has been provided via a WWW server. As this revision has significantly different astrometry from the GSC currently used by HST 44 Chapter 3: Fixed and Generic Targets [Generic _Targets] operations (version 1.1), GSC version 1.2 must not be used for Phase 2 target determinations. Note that all GSC CD ROMs in circulation are from version 1.1 or lower. Uncertain or Unknown Coordinates If it is impossible to obtain adequate plate material to measure coordinates to the required accuracy (e.g., a very crowded field which cannot be resolved using ground-based observations), it may be necessary to obtain an early acquisition image or to perform an acquisition that involves real-time interaction with the telescope (see Target Acquisition on page 134). In that case, coordinates as accurate as possible must be entered on the Target List. Special Catalogs The option PLATE-ID can be used to specify one of the special guide star catalogs which have been created by the STScI to accommodate special guide star requirements. These catalogs are primarily used for selecting guide stars from a subset of stars in the region which have certain properties or more accurate relative positions. This option is most commonly used when the relative accuracy of guide stars and target stars must be known with great precision. The Special Catalogs currently available are: PLATE-ID SKY REGION ZZZZ NGC188 ZZZX Iota Carinae ZZZW HR6636 ZZZV HR6850 ZZZU HR6945 ZZZT NGC5617 ZZZR Omega Centauri ZZZQ Eta Carinae Only a modest number of specific objects are listed in these catalogs; contact your PC. Equinox for Coordinates [Equinox] 45 Equinox for Coordinates [Equinox] Specify the year of the equator and equinox to which the coordinates are referred, optionally preceded by a J or B to indicate the Julian or Besselian system. Integer or decimal values for the year may be used. If the year is given without a prefix (for example, 1975), the Besselian system is assumed for years prior to 2000 and the Julian system is assumed for the year 2000 and beyond. If a prefix is given, it must be B for years prior to 2000 and J for the year 2000 and beyond. The values J2000 and B1950 correspond to commonly used catalogs; it is recommended that one of these be specified unless there is a good reason to use something else. It is not necessary to apply precession corrections to coordinates from positional catalogs. The Guide Star Catalog and the Hipparcos Input Catalogue both use the J2000 equinox. (Note, however, that the Hipparcos output catalogue is epoch 1991.25, which means proper motions can have significant effects if you are not careful.) An Equinox value is required. For some notes on Equinox, Epoch, and units, see Getting Coordinates Coordinated on page 58. Source of Specified Coordinates [Coordinate_Source] In this field please specify the source of the celestial coordinates that you list for each target. Most faint targets will use “Other_Source.” Valid entries are: Guide_Star_Catalog To be used if the source is the HST Guide Star Catalog. Include the Plate ID (from the “Plt” column in the GSC) with your coordinates. Note: If the Plt value is 56, then the true source is the Hipparcos Input Catalogue, which should be listed (see below, and please note that Plate ID should not be specified). 46 Chapter 3: Fixed and Generic Targets [Generic _Targets] GSC_Survey_Plate To be used if coordinates were measured from a Guide Star Catalog survey plate. Include the Plate ID with your coordinates, taking it from the PLATEID keyword in the FITS header. HST_Image To be used if coordinates were measured from an existing HST image. Include the Plate ID, which can be determined from the guide star IDs listed in the observation’s Standard Header Packet. All HST observations have at least one guide star ID in the Standard Header Packet (SHP). SHP data are in the _jif.fits file for WFPC2 observations, or in the .spt file for STIS data. The guide stars that were used during any pointing of HST will be recorded in the SHP as character strings associated with specific header keywords. The primary, or dominant, guide star is given by the GSD_ID keyword, while SGESTAR lists the secondary, or sub-dominant, guide star. The guide star ID is a concatenation of the star number, the region number (from the Guide Star Catalog), and the particular FGS used in the pointing. For example, “0123406789F2” means guide star 01234 06789 was used with FGS2. To find the Plate ID, go to the GSC web site: http://www-gsss.stsci.edu/support/phase2.html The form will prompt you for the guide star ID (in two fields); you should use only the primary guide star. You should then be given the coordinates, estimated magnitude, associated errors, flags internal to the catalog structure, and the PLATE-ID. For most guide stars there will be multiple entries (and multiple PLATE-IDs because the fields of the plates overlapped. The first line of the output lists the primary plate, and this is the one you should list. If the observation used only a single guide star then it is possible that a a secondary plate was used; contact your Contact Scientist. Image_Tied_To_GSC_Frame To be used if you measured several visible stars on a Guide Star Catalog survey plate and then used them to determine pseudo-GSC coordinates for a target imaged with another telescope. Include the Plate ID (from the PLATEID keyword in the FITS header) with your coordinates. Radial Velocity or Redshift [RV_or_Z] 47 PPM_Star_Catalogue To be used if coordinates are from the PPM (Catalog of Positions and Proper Motions). Hipparcos_Input_Catalogue To be used if coordinates are from the Hipparcos Input Catalogue, or, equivalently, they are from the Guide Star Catalog and the “Plt” column lists “56” (in this instance please do not specify plate ID). Because of systematic differences in coordinates, we urge you not to use the HIC as a coordinate source; the Hipparcos/Tycho Catalogue should be used instead. Hipparcos/Tycho_Catalogue To be used if the coordinates are from the Hipparcos/Tycho missions. Note that coordinates from the Hipparcos/Tycho_Catalogue have equinox J2000 but epoch 1991.25. This earlier epoch means that it is important to provide a proper motion for your target if it is at all significant. In some cases the Catalogue of Positions and Proper Motions (PPM) may be a better source for proper motions because of its longer time baseline. Other_Source: <text> To be used if none of the above apply to your coordinates. You must include a short description of where the coordinates are from, for example: Coordinate_Source: Other_Source: HDF Catalog (Williams et al. 1996, AJ, 112, 1335) The explanation cannot be very long, and so we recommend an entry like “Coordinate_Source: Other_Source: See comment” if you need more space. Radial Velocity or Redshift [RV_or_Z] Give, if known, the heliocentric radial velocity or redshift of the target. The format is V = <velocity in km/sec> or Z = <redshift>; examples are V = +1198 and Z = 1.95. The units must not be specified. 48 Chapter 3: Fixed and Generic Targets [Generic _Targets] Is Proper Motion or Parallax Relevant? If a small aperture or occulting spot is to be used, even a relatively small proper motion or parallax may cause difficulties in acquiring the target. In such cases, the Proper Motion/Parallax data must be provided. Note, however, that proper motion and parallax values may not be specified for a target which is specified by a positional offset. Such targets will be taken to have the same proper motion and parallax as the reference target. Offset targets have coordinates given with (RA–OFF, DEC–OFF), (ETA–OFF, XI–OFF), or (R, PA). The observer must determine whether or not proper motion or parallax is relevant. In general, this will depend on the size of the acquisition aperture of the SI that will be used and the epoch of the coordinates that have been provided. For example, the STIS uses a target acquisition area of 5 arcsec square. For a star whose coordinates are given for the epoch 1950, and that will be observed in 1997, a proper motion of approximately 0.5*2.5/(1997–1950) = 0.027 arcsec per year would be “relevant,” with a resulting offset of half the minimum center-to-edge distance. If special plate catalogs are being used (see Special Catalogs on page 44), proper motions are probably not included (the HST Guide Star Catalog, for example, does not include proper motion). If the relative accuracy of the target and guide stars is essential, the proper motion should be included for the target star if the special catalog includes proper motions. Proper Motion and Parallax Data The following information is required for targets where proper motion and parallax are “relevant”; note that uncertainties for RA_PM, Dec_PM, and Annual_Parallax are not required. If a sign is not given for RA_PM or Dec_PM, a positive value will be assumed, but it is better to be explicit. • RA_PM: For Proper Motion in RA, the value should be in units of seconds of time/year. To convert from arcsec/year to seconds of time/year, divide by 15 cos DEC. • Dec_PM: For Proper Motion in DEC, the value should be in units of arcsec/year. • Epoch: The “Epoch of position” is the date of the “Target Position” which was defined in the Target List (see Target Position [Position] on page 34). • The “Epoch of position” may or may not be the same as the date of “Equinox for Coordinates” in the Target List (see Equinox for Coordinates [Equinox] on page 45). Remember that the “Epoch of posi- Flux Data [Flux] 49 tion” is the date the target position is referred to, whereas the “Equinox of Coordinates” is the date of orientation of the coordinate system in which the position is measured. For example, a star with a large proper motion may have its coordinates given in the J2000 system, but the numbers themselves are for epoch 1984, meaning that the star was at the specified position on January 1, 1984. As with Equinox, Epoch should be of the form B19xx for years before 2000, and J20xx for 2000 and later. • Ordinarily the epoch of position is earlier than the present date. In the Guide Star Catalog (GSC), the equinox is J2000 while the epoch depends on the individual plate. Do not adjust your coordinates to be those that would be measured if the plate were taken in the year 2000. However, some catalogs contain coordinates already adjusted to an epoch of J2000: the Hipparcos Input Catalogue (often used in the GSC for stars brighter than m(V) ~= 9) and the PPM Star Catalog. When these catalogs are being used, it is appropriate to specify an epoch of J2000. (These remarks do not apply to the Hipparcos Output Catalog.) • Annual_Parallax: The unit for parallax is arcsec. The example below is for the object DM–9D697 (Epsilon Eridani), where the proper motion data are taken from the SAO Catalog. RPS2 Keyword Explanation Units Example RA_PM: Proper Motion in RA sec/yr –0.0662 DEC_PM: Proper Motion in DEC arcsec/yr 0.019 Epoch: Epoch of Position Byyyy or Jyyyy B1950 Annual_Parallax: Annual parallax arcsec 0.30488 For some notes on proper motions and units, see Getting Coordinates Coordinated on page 58. Flux Data [Flux] Flux information must be provided for all targets, and there can be more than one entry for a given target. All entries are values as observed at the Earth, rather than intrinsic values. STScI uses flux information to test for over-illumination of sensitive detectors. In particular, STIS proposals cannot be implemented without flux information for all targets and other sources in the fields of view 50 Chapter 3: Fixed and Generic Targets [Generic _Targets] because of the critical requirements to protect its detectors from damage by excessively bright objects. The first flux information given should generally be a broad-band magnitude or surface brightness. For stars, the spectral type and color index should also be included (when possible). As many additional flux values as appropriate for the requested exposures should be provided. For example, ultraviolet or emission-line fluxes should be given if the target is to be observed in the ultraviolet or through a narrow-band filter, or several magnitudes might be provided if the target is a variable star to be observed at various brightness levels. In some cases (Targets of Opportunity, variable objects, etc.) the estimated flux data may be very uncertain, but the best available estimates should nevertheless be given, along with appropriate uncertainties and comments. It may be important to specify the flux of a background source as well as the target flux. For example, a globular cluster in M87 may be seen against the bright background of the galaxy. The keyword –BKG should be appended to a background flux specification in this case (see footnote b to Table 3.13). Use a comma to separate entries if more than one flux value is given. Flux must be given as F(lambda) rather than F(nu). Recall that the conversion is: F(lambda) = (3 x 10^18 F(nu)) / lambda^2, where lambda is in Ångstroms and F(nu) is in erg/(cm^2 sec Hz). For example, if lambda = 1500Å, and F(nu) = 1.0 x 10^-26, then F(lambda) = 1.3 x 10^-14. The flux data are to be expressed in the format shown in Table 3.13. Do not enter explicit units. General Guidelines on What Flux Data to Include The following summary provides general guidelines for what flux information must be included in five general cases. See the Instrument Handbooks for more detailed descriptions of how to make the exposure time calculations. Point source, non-dispersive instrument 1. Target flux: V magnitude, (B–V), E(B–V), spectral type. Flux at specified wavelength may be substituted for V magnitude. If no entry for E(B–V) is given, E(B–V) = 0 will be assumed. Flux Data [Flux] 51 2. Background (optional): Broad-band surface brightness or surface brightness at specified wavelength; –BKG must be specified in the name of the flux parameter. 3. Flux in wavelength range of observation. Extended source, non-dispersive instrument 1. Target flux: V surface brightness, (B–V), E(B–V). Flux at specified wavelength may be substituted for V surface brightness. If no entry for E(B–V) is given, E(B–V) = 0 will be assumed. 2. Background (optional): Broad-band surface brightness or surface brightness at specified wavelength; –BKG must be specified in the name of the flux parameter. 3. Surface flux at wavelength of observation and size of the region specified. Point source, dispersive instrument 1. Target flux: V magnitude, (B–V), E(B–V), spectral type. Flux at specified wavelength may be substituted for V magnitude. If no entry for E(B–V) is given, E(B–V) = 0 will be assumed. 2. Background (optional): Surface brightness of continuum; –BKG must be specified in the name of the flux parameter. 3. Continuum flux in wavelength range of observation. 4. Line flux and line width of brightest emission line in the wavelength range of observation. Extended source, dispersive instrument 1. Target flux: V surface brightness, (B–V), E(B–V). Flux at specified wavelength may be substituted for V surface brightness. If no entry for E(B–V) is given, E(B–V) = 0 will be assumed. 2. Background (optional): Surface brightness of continuum; –BKG must be specified in the name of the flux parameter. 3. Surface flux at wavelength of observation and size of the region specified. 4. Line surface flux and line width of brightest emission line in the wavelength range of observation. 52 Chapter 3: Fixed and Generic Targets [Generic _Targets] Infrared source 1. Target flux: J magnitude, (J–K). Flux at specified wavelength may be substituted for J magnitude. 2. Background (optional): Broad-band surface brightness at specified wavelength; –BKG must be specified in the name of the flux parameter. 3. Note that this refers to the astronomical background and not the thermal background. 4. Flux in wavelength range of observation. Note that this must be in units of erg/(cm^2 sec Å). The NICMOS units conversion tool on the STScI WWW pages can help you convert your source flux from J magnitude or flux in Janskys into this flux unit. Note: Details of how the above flux information was derived must be given in the proposal text section in the Observing_Description (see the Call for Proposals). If any of the required flux data cannot be provided or are deemed to be unnecessary, these points must also be explained in that section. Incomplete flux information may delay the implementation of your proposal, especially in the case of STIS observations. Table 3.13: Formats for Specification of Target Flux Data Parameter Format example Units Broad-band magnitudea V=13.1 +/– 0.5 magnitude Spectral type TYPE=G5III Color Indexa B-V = 0.86 +/– 0.2 magnitude Color Excess E(B-V) = 0.3 +/– 0.2 magnitude Background Surface Brightnessb SURF-BKG(B) = 20 +/– 0.2 mag/arcsec2 Examples for Stars: Examples for Galaxies, Nebulae, and other extended sources: Surface Brightnessa,b SURF(V) = 25.0 +/– 1.0 mag/arcsec2 Surface Brightnessa SURF(B) = 24.5 +/- 0.5 mag/arcsec2 Bright-Object Constraints Parameter Format example Units Color Excess E(B-V) = 2.5 +/– 0.2 mag 53 Plus whatever other fluxes are relevant to your science program. Some other examples are listed below: Interstellar Extinction A(V) = 1.3 +/– 0.1 mag Flux at a specified wavelength F(5100) = 51 +/– 3 E-15 erg/(cm2 sec Å) Continuum Fluxc F-CONT(3500) = 57 +/– 3 E-15 erg/(cm2 sec Å) Line Fluxc,d,e F-LINE(3727) = 5 +/– 1 E-14 erg/(cm2 sec Å) Line Widthf W-LINE(3727) = 2.4 +/– 0.2 Å Surface Brightness at specified wavelengthb SURF(5100) = 11 +/– 2 E-15 erg/(cm2 sec Å arcsec^2) Surface Brightness at continuum wavelengthb SURF-CONT(5000) = 52 +/– 2 E-15 erg/(cm2 sec Å arcsec^2) Surface Brightness of line emissionc,d,e SURF-LINE(5007) = 52 +/– 2 E-15 erg/(cm2 sec arcsec^2) Size (FWHM of circular region)g SIZE = 25 +/–5 arcsec a. The following broad-band magnitudes may be used: U,B,V,R,I,J,H,K. b. You may append “–BKG” to this reference (just before the wavelength designation) to indicate that it is a background flux value (e.g., SURF-BKG(V) = 18.2 +/– 0.5; SURF-CONT-BKG(5100) = 10 +/– 3 E-15). c. Give wavelength used in keyword in rest frame, but flux in observed frame. d. Line flux should be relative to the continuum, if specified, or relative to zero if not specified. e. Whenever the S/N refers to a spectral line, W-LINE must be given along with F-LINE or SURF-LINE. Values of F-LINE and SURF-LINE outside the Earth’s atmosphere are required. f. W-LINE is the full width at half maximum (FWHM). g. SIZE should be included if the exposure time estimate assumed the flux was spread over an extended region; if omitted, the highest spatial resolution of the observing mode will be assumed. Bright-Object Constraints Several of the Scientific Instruments must be protected against over-illumination. Table 3.14 summarizes the safety restrictions by instrument. You should not propose observations which violate these guidelines. Non-linearity, saturation, or other temporary effects which may occur at substantially fainter limits than those identified below are described in the Instrument Handbooks. 54 Chapter 3: Fixed and Generic Targets [Generic _Targets] Table 3.14: Bright-Object Constraints Instrument Description STIS The STIS MAMA (UV) detectors are subject to strict bright-object controls to prevent potentially fatal damage. Maximum permissible local and global count rates have been established for the STIS MAMA detectors, both for imaging and spectroscopy; see the STIS Instrument Handbook. These limits have been translated into extensive tables of magnitude and flux guides for the various configurations and modes; consult the STIS Instrument Handbook. Some of these limits are quite faint. All potential targets should be checked for safety with the STIS Exposure Time Calculator on the Web. Measured UV fluxes must be provided for any objects within 1 magnitude of the spectroscopic limits; if not previously available, they must be first observed with a safe STIS mode. Magnitudes and colors, or a UV image, must be provided for all objects in the fields of proposed PRISM and MAMA direct-imaging observations, including the background fields of solar-system targets. There are no safety-related brightness limits for the STIS CCD. See the STIS Instrument Handbook for a description of saturation levels, residual charge, and other effects. WFPC2 There are no safety-related brightness limits for the WFPC2. See the WFPC2 Instrument Handbook for a description of saturation levels, residual charge, etc. FGS The FGS may not be used to view objects brighter than mV = 1.8. The FGS may view objects brighter than mV = 8.0 only if the neutral-density filter is in place. Table 3.15: Bright-Object Constraints for NICMOS (Restricted) Instrument Description NICMOS There are no safety-related brightness limits for the NICMOS. See the NICMOS Instrument Handbook for a description of saturation levels, residual charge, etc. Comments [Comments] Information that cannot be made to conform to the required formats may be entered in a “Comments” line. Comment lines are not interpreted by the software, but are maintained in the data base and do appear on printouts of the forms. Generic Targets List [Generic_Targets] 55 Generic Targets List [Generic_Targets] Generic targets are those that during Phase 2 can only be described in terms of astronomical characteristics or general location in the sky. This category is used only for Targets of Opportunity and parallel exposures. For parallel exposures, both pure-parallel and coordinated-parallel (see Chapter 6: Parallel Science Exposures on page 101), the pointing is determined by the primary observation, and the specification of a generic target for the parallel exposure denotes a region within which the parallel aperture is expected to point. If the parallel pointing does not matter and the intent is simply to sample whatever the parallel aperture happens to detect, it is not necessary to define a generic target; instead the special target ANY should be used (see Target Name [Target_Name] on page 93). Note: Generic Target region coordinates are assumed to be in the J2000 reference frame. Target Number(s) [Target_Number] Generic targets should be given individual names and numbers just like fixed targets; however, it is possible to enter a range of target numbers associated with a single target name. If a range is specified, the number of targets must reflect the number of separate fields that will be observed. For example, if WFPC2 observations of 10 different fields, all named QSO-SURVEY-FIELD, are required for a quasar search, the value of the Target_Number keyword would be 1–10. Target Name [Target_Name] A descriptive name must be provided. If a name cannot be specified in advance, a provisional name should be supplied. When the actual observation is made, a more specific name will be added to the target designation. Either the provisional name or the updated name can then be used for archival searches (e.g., SN might be the provisional name, while SN-1995D might be the updated name). A unique target name must be assigned to each generic target. Target Description [Description] See Target Description [Description] on page 29. 56 Chapter 3: Fixed and Generic Targets [Generic _Targets] Flux Data [Flux] See Flux Data [Flux] on page 49. Flux data are not required for pure parallel observations of generic targets. Comments [Comments] See Comments [Comments] on page 54. Generic Target Specifications A way to specify generic celestial regions and target lists in a machine-readable fashion is described below, and should be used for the Generic Targets List. It is important that these instructions be followed in order for pure parallels with generic targets to be schedulable. Two types of generic target specifications are permitted: • Region generic targets: a celestial region specified in one of three coordinate systems • Target Lists: lists of fixed or generic targets The Selection Criteria column should use the syntax specified below whenever the selection criteria can be fully specified by a celestial region in one of the supported coordinate systems, or by a list of fixed or generic targets. In all other cases a text description should continue to be provided after the “Other:” header. Region Generic Targets Three coordinate systems are supported: • Equatorial: right ascension (RA) and declination (DEC) • Galactic: Galactic longitude (LII) and Galactic latitude (BII) • Ecliptic: ecliptic longitude (LAMBDA) and ecliptic latitude (BETA) Regions may be any of: 1. “Rectangular” regions, i.e. bounded by latitude and longitude limits in the appropriate coordinate system 2. Circular regions, specified as within some angular limit of a point specified in any of the three supported coordinate systems 3. Polar caps or equatorial bands in any supported coordinate system Generic Targets List [Generic_Targets] 57 The following table provides examples of each of these types of region specifications. Note that the same rules for specifying RA and Dec apply as for fixed targets (See “Equatorial Coordinates” on page 36.) Equatorial coordinates Galactic coordinates Ecliptic coordinates RA = 5H 30M 0S +/180M, LII = 45D+/-10D, LAMBDA = 56D+/-5D, DEC = -65D +/- 10D BII = 15D+/-10D BETA = 60D+/-15D RA = 1H 30M 0S, LII = 0D, LAMBDA = 45D, DEC = -15D, R=10D BII = 15D, R=5D BETA = -15D, R = 5.5D polar cap DEC > 60D BII < -30D BETA > 10D both polar caps ABS_DEC > 60D ABS_BII > 30D ABS_BETA > 10D equatorial band ABS_DEC < 10D ABS_BII < 30D ABS_BETA < 45D Region type rectangular circular Note that for rectangular and circular regions, the syntax is identical to that of fixed target regions except that the indicator REGION is omitted, and galactic and ecliptic coordinates are allowed. Target Lists In some cases it may be desirable to specify as a Generic Target any of a list of Fixed Target positions or Generic Target regions. In this case the fixed targets should be provided as usual on the Fixed Target List, and the generic target regions should be specified as above on the Generic Target List. Then a new generic target can be defined with Selection Criteria specified by: TARGETS = <target-number-list> This will be taken to indicate that any of the targets in <target-number-list> are suitable as targets. Note that target numbers are required to be unique across all targets in a proposal, whether on the Fixed, Generic, or Solar System Target Lists. This type of target is particularly useful when a known list of objects of interest is available, and it is desired to observe one of these objects with an imaging SI when a primary exposure with a spectrograph is positioned appropriately nearby. 58 Chapter 3: Fixed and Generic Targets [Generic _Targets] Getting Coordinates Coordinated Observers are responsible for the accuracy and appropriateness of the coordinates they supply and any changes made to them. Only you can determine where we should point HST. Equinox is always a critical quantity when specifying coordinates. All astronomical coordinates change with time because of the precession of the Earth’s rotation axis. Equinox specifies a time to which a coordinate system is tied. Thus J2000 refers to the location of an object in celestial coordinates for the coordinate reference frame of January 1, 2000. Epoch is generally important only for objects that move. In particular, the epoch of a star’s coordinates refers to a specific time at which the star is at that location. For example, the Hipparcos output catalogue lists coordinates of the brighter stars in the ICRS reference system (which is very nearly the same as J2000), and the coordinates themselves are for epoch 1991.25. The proper motions in the Hipparcos output catalogue are also epoch 1991.25, the midpoint of the mission. If you specify the epoch and equinox correctly, we can easily compute the location of an object at the time it will be observed with HST. (Note: An epoch is purely a time, and one of the form "J1991.25" is nonsensical.) Proper motions sometimes cause problems. Units are especially crucial. The proper motion in Right Ascension (RA_PM) is to be listed in sec/yr, meaning seconds of time per year. If you have a value for RA_PM in arcsec per year, you need to divide it by 15 (to convert from arcsec to time sec), and to then divide by cos δ because lines of constant RA converge in going to the poles. DEC_PM is almost always listed in arcsec/yr, which are the units needed for HST observing. As we have emphasized above, we urge to use signs on quantities, even when they are not required. A value of +0.060 for RA_PM, say, makes it clear that the sign has been considered. Just specifying 0.060 leaves ambiguity because sometimes observers forget a minus. One more thing: be very careful if your target lies near a celestial pole. Many precession routines break down in this regime, and uncertainties in position can cause problems too. Also, patterns that you may execute with an instrument could cross the pole, leading to confusion in position. All these issues can be resolved, but careful attention is needed. CHAPTER 4: Solar System Targets List [Solar_System_Targets] For an explanation of this engineering-only version, see Special Note to Engineering Version Users in Chapter 1: About This Document on page 1-3. In this chapter . . . Target Number [Target_Number] / 61 Target Name [Target_Name] / 62 Target Description [Description] / 64 Target Position / 65 Target Position Level 1 [Level_1] / 66 Target Position Level 2 [Level_2] / 68 Target Position Level 3 [Level_3] / 75 Ephemeris Uncertainty [Ephem_Uncert] / 75 Acquisition Uncertainty [Acq_Uncert] / 75 Observing Windows [Window] / 76 Flux Data [Flux] / 82 Comments [Comments] / 84 Illustrations of Orbital Longitude / 84 Examples of Target List Blocks / 85 59 60 Chapter 4: Solar System Targets List [Solar_System_Targets] Tables and Figures Table 4.1: Solar System Standard Targets Table 4.2: Target Description Keywords Table 4.3: Positional Parameters for TYPE = COMET Table 4.4: Positional Parameters for TYPE = ASTEROID Table 4.5: Parameters for TYPE = PGRAPHIC Table 4.6: Parameters for TYPE = POS_ANGLE Table 4.7: Parameters for TYPE = MAGNETO Table 4.8: Parameters for TYPE = TORUS Table 4.9: Parameters for TYPE = SAT Table 4.10: Parameters for TYPE = PCENTRIC (Available but Unsupported) Table 4.11: Keywords for Observing Windows Table 4.12: Operators for Observing Windows Table 4.13: Formats for Specification of Target Flux Data Figure 4.1: Orbital Longitude for Satellites / 84 Figure 4.2: Orbital Longitude for Planets / 85 HST is able to point at and track solar system targets with sub-arcsecond accuracy. In order for target acquisition and tracking to succeed, planetary observers must specify positions for their targets in a precise and unambiguous manner. Therefore, it is imperative that the Solar System Target List (SSTL) be carefully and correctly completed. This section explains how to fill out the SSTL for any solar system target. Ephemerides are generated using fundamental ephemeris information from NASA’s Jet Propulsion Laboratory (JPL). Ephemerides can be generated for all known types of solar system targets, including planets, satellites, comets, asteroids, surface features on planets and satellites, and offset positions with respect to the centers of all the above bodies. The following instructions demonstrate how to define solar system targets in a way that allows accurate ephemeris generation. The body-axes definitions, body dimensions, directions of rotation poles, rotation rates, and the definitions of cartographic coordinates used by STScI are normally identical to the values adopted in the report of the “IAU Working Group on Cartographic Coordinates and Rotational Elements of the Planets and Satellites: 1982” (Davies, M.E., et al., Celestial Mechanics, 29, 309-321, 1983). In a few instances, the latter data have been updated due to new results obtained from the flyby spacecraft. Target Number [Target_Number] 61 Also, some new bodies have been added which were unknown at the time of the IAU report. For Jupiter and Saturn, the lambda(III) coordinate system is assumed, but lambda(I) or lambda(II) can be used. For Uranus and Neptune, coordinates follow the “Report of the IAU/IAG/COSPAR Working Group on Cartographic Coordinates and Rotation Rates of the Planets and Satellites” (Celestial Mechanics and Dynamic Astronomy, 46, 197, 1989). If you need further information on these, please contact your Program Coordinator. One exception exists to the requirements outlined above. Observers for solar system Targets of Opportunity (e.g. a “new” comet or asteroid, a solar-wind disturbance reaching the Jovian magnetosphere, etc.), should complete the Generic Target List (See “Generic Targets List [Generic_Targets]” in Chapter 3.) and the Visit and Exposure Specifications (to the extent possible) in time for the Phase 2 deadline. If and when a suitable target appears, the proposer must complete the Solar System Target List and update the Visit and Exposure Specifications. No target can be observed until the complete Phase 2 information is provided. In this chapter, each heading has a description followed by a keyword in square brackets (e.g., Target Number [Target_Number]). The keyword must be used in your RPS2 form. Elsewhere, items in boldface (e.g., RA-OFF) show words or phrases to be used directly as RPS2 entries. Items in brackets (e.g., <value>) show entries you are to provide. Parameters listed in square brackets (e.g., [A1 = <value>]) are optional, whereas those not in square brackets are required. Target Number [Target_Number] Each target that will be observed must be assigned a unique target number. Target numbers must be positive, monotonically increasing (but not necessarily consecutive) integers. A different target should be defined whenever a different target position or timing description is required. For example, separate targets should be defined if you plan to take spectra of several different surface features on a planet, or if you plan to observe the same feature with different timing constraints. If more than one type of Target List is used (if your program also requires filling out the Fixed Target List or the Generic Target List), the target numbers should continue consecutively from one list to the next. All target numbers within a proposal must be unique. 62 Chapter 4: Solar System Targets List [Solar_System_Targets] Target Name [Target_Name] The name is used to identify a target; all target names within a proposal must be unique. The target name can be selected from the STScI list of standard targets (see Table 4.1; explanations of “Level 1” and “Level 2” are given below), or a name can be defined by the GO. The use of standard names is encouraged whenever it is possible. The following conventions should be followed in naming targets: • The maximum allowable length of a target name is 31 characters. • No blanks are permitted in target names. A hyphen should replace blanks that would normally be used to separate fields (e.g. IO-TORUS, COMET-BRADFIELD-1979X). • Only letters and numerals are allowed in target names; punctuation (other than hyphens and + or –) is not permitted. • Target names must begin with a letter, not a numeral. • Construct target names so they make sense for your observing program. For example, if your program consisted of consecutive observations of three surface features on Mars, then three appropriate target names might be: MARS-FEATURE1, MARS-FEATURE2, and MARS-FEATURE3. Do not use just a standard name for a target when a specific portion of a body is being observed. For example, do not use “Saturn” as the target name for a feature or specific location that is defined relative to the position of Saturn as a standard body because this is confusing for the software that computes the positions of moving targets. Target Name [Target_Name] 63 Table 4.1: Solar System Standard Targets Level 1 Level 2 Sun Mercury Venus Earth Moon Mars Phobos Deimos Jupiter Io Europa Ganymede Callisto Amalthea Himalia Elara Pasiphae Sinope Lysithea Carme Ananke Leda Thebe (1979J2) Adrastea (1979J1) Mimas Enceladus Tethys Dione Rhea Titan Hyperion Iapetus Phoebe Janus (1980S1) Epimetheus (1980S3) Helene (1980S6) Telesto (1980S13) Calypso (1980S25) Atlas (1980S28) Prometheus (1980S27) Pandora (1980S26) Pan Ariel Umbriel Titania Oberon Miranda Cordelia (1986U7) Ophelia (1986U8) Bianca (1986U9) Cressida (1986U3) Desdemona (1986U6) Juliet (1986U2) Portia (1986U1) Rosalind (1986U4) Belinda (1986U5) Puck (1985U1) Triton Nereid Naiad Thalassa Despina Galatea Larissa Proteus Metis (1979J3) Saturn Uranus Neptune Pluto Charon If you are uncertain whether or not your target can be referenced by name, contact your Program Coordinator for guidance. 64 Chapter 4: Solar System Targets List [Solar_System_Targets] Alternate names are given in parentheses for some bodies but these should not be listed in the RPS2 file. They are given here for identification purposes only. Target Description [Description] The target description is used to sort the solar system targets by class and will be useful to archival researchers. The first word in any target description must be one of the keywords listed below. The keyword is then followed with text that depends on the target class as described below. Table 4.2: Target Description Keywords Keyword Description PLANET If the target is the center of a planet, enter PLANET followed by the name of the planet (e.g., PLANET JUPITER, PLANET SATURN). SATELLITE If the target is the center of the satellite of a planet, enter SATELLITE followed by the satellite name (e.g., SATELLITE GANYMEDE, SATELLITE 1980S27) COMET If the target is the nucleus of a comet, enter COMET followed by its common name or catalog designation (e.g., COMET HALLEY, COMET 1979X) ASTEROID If the target is the center of an asteroid, enter ASTEROID followed by its common name or its catalog number (e.g., ASTEROID CERES, ASTEROID 452) FEATURE If the target is a surface feature, enter FEATURE followed by the name of the parent body (e.g., FEATURE JUPITER, FEATURE IO) OFFSET If the target is an offset position with respect to a solar system body (but not a feature on its surface), enter OFFSET followed by the name of the parent (reference) object (e.g., OFFSET COMET HALLEY, OFFSET JUPITER) RING If the target is in a ring, enter RING followed by the name of the parent object (e.g., RING JUPITER, RING SATURN) TORUS If the target is a plasma torus, enter TORUS followed by the name of the parent object (e.g., TORUS JUPITER) OTHER If your target cannot be classified under any of the categories above, then enter OTHER followed by some description of the type of observation planned (e.g., ASTROMETRIC REFERENCE, INTERPLANETARY MEDIUM, ZODIACAL LIGHT) Target Position 65 Target Position Target pointing Specification (TPS) and “Levels” Three fields are used to describe the target’s position, referred to here as the Target Pointing Specification (TPS). The TPS has been defined using a hierarchical structure. • Level 1 refers to a target in orbit about the Sun. Examples of Level 1 targets include planets, asteroids, and comets. When a Level 1 object is the desired target for observation, complete the Level 1 field and leave the other two target position fields blank. • Level 2 refers to a target whose motion is normally described with respect to a Level 1 object. Examples of Level 2 targets include planetary satellites, surface features on planets or asteroids, and non-nuclear positions in the coma of a comet. When a Level 2 object is the desired target for observations, the Level 1 field contains information on the parent body, and the Level 2 field gives positions relative to this body. In this case, leave the Level 3 field blank. • Level 3 refers to a target whose motion is normally described with respect to a Level 2 object. Examples are a surface feature on a planetary satellite or a pointing which is offset from the center of a planetary satellite. When a Level 3 object is the desired target for observation, then all three fields must be completed, with Level 1 giving the parent of the body described in Level 2, and Level 3 giving the position of the observed target with respect to the body in Level 2. No more than three levels are allowed. If you believe that your target cannot be described in this form, contact your Program Coordinator. Describing Targets The targets specified in the target position fields can be described in up to four ways: • By a name selected from a list of targets • By orbital elements • By coordinates with respect to another object • Via target selection during a real-time observing session 66 Chapter 4: Solar System Targets List [Solar_System_Targets] Table 4.1 gives the list of valid names for solar system targets. PIs are responsible for obtaining up-to-date orbital elements for bodies not in this table. Objects must be denoted by their IAU-adopted name. A good reference for object names can be found in the Astronomical Almanac, and in the Marsden comet catalog (Marsden, B. G., Catalog of Cometary Orbits, Enslow Publishers, Hillside, NJ, 1983). If you are uncertain whether or not your target can be referenced by name, contact your Program Coordinator. In those cases where the target’s position is given with respect to one of the standard objects, the latest available data from JPL on the bodies’ physical dimensions, orientation, and rotation rates are used in calculating the target’s position. In those cases where all or part of the TPS for your target can be described using standard names, we strongly recommend that you do so. Generally, this will result in the most accurate ephemeris generation for your target. Specifying Time Whenever there is an entry involving “time” (anywhere on the form), the format for that entry must be: DD-MMM-YYYY:hh:mm:ss.s, where DD is the day of the month, MMM is the first three letters of the month name, YYYY are the full four digits of the Gregorian calendar year, hh is the hour, mm is the minute, and ss.s are the decimal seconds. Only the necessary precision need be specified. Examples: 02-AUG-1993:13:04:31 15-JAN-1994 Two different systems of time are used in this document. TDB refers to Barycentric Dynamical Time and can be considered synonymous with ET (Ephemeris Time), which was used before 1984. UTC refers to Coordinated Universal Time. The precise interpretation of each time value depends on the context in which it is used. Target Position Level 1 [Level_1] Specify your target in one of the following ways: 1. STD = <object name>, where the name must be from Table 4.1, or 2. TYPE = <name>. The TYPE = <name> target description allows the specification of Target Position 67 non-standard targets in a variety of formats and must be the first entry in the field if it is used. - If COMET is chosen, then a set of 2-body orbital elements in the IAU Circular format must be supplied for the target. - If ASTEROID is chosen, then a set of 2-body orbital elements in the Minor Planet Circular format must be supplied. For all cases, the required input data are described below. If the data are valid only over a specific period of time, then specify this time interval in the Window field according to the rules given later. COMET and ASTEROID Positional Parameters Table 4.3: Positional Parameters for TYPE = COMET Q = <value> Perihelion distance, in AU E = <value> Eccentricity I = <value> Inclination, in degrees O = <value> Longitude of ascending node, in degrees W = <value> Argument of perihelion, in degrees T = <value> Time of perihelion passage, in TDB EQUINOX = <value> either B1950, or J2000 EPOCH = <value> Osculation date, in TDB (4 digits) [A1 = <value>] Radial component of non-gravitational acceleration (AU/day^2) [A2 = <value>] Component of non-gravitational acceleration lying in the orbital plane and parallel to the instantaneous velocity vector (AU/day^2) [A3 = <value>] Component of non-gravitational acceleration directed perpendicular to the plane defined by A1 and A2 (AU/day^2) Table 4.4: Positional Parameters for TYPE = ASTEROID A = <value> Semi-major axis, in AU E = <value> Eccentricity I = <value> Inclination, in degrees O = <value> Longitude of ascending node, in degrees W = <value> Argument of perihelion, in degrees M = <value> Mean anomaly at EPOCH, in degrees EQUINOX = <value> either B1950, or J2000 EPOCH = <value> Osculation date, in TDB (4 digits) 68 Chapter 4: Solar System Targets List [Solar_System_Targets] The elements given above refer to the mean ecliptic and equinox of either B1950 or J2000 depending on which “value” is specified for EQUINOX. An example of TYPE = COMET is shown in the “Example Target List Blocks” below for Example 3. However, notice in this example that the Level 1 target (Comet Halley) is a standard object and could have been listed on the form by name. It is the responsibility of the observer to supply accurate orbital elements to STScI when specifying TYPE=COMET or TYPE=ASTEROID. Target Position Level 2 [Level_2] Five Target Reference Systems (TRSs) are described in the following paragraphs. Please pay careful attention to the definitions of each TRS. Specify your target in one of the following ways: STD = <object name> or TYPE = <name> In this case <object name> is from Table 4.1: Solar System Standard Targets, or the Type is: PGRAPHIC planetographic coordinates relative to Level 1 target POS_ANGLE polar coordinate offsets from Level 1 target MAGNETO position in magnetic coordinate system TORUS line-of-sight projected coordinate system SAT orbital elements of a satellite For the PGRAPHIC, MAGNETO, and TORUS coordinate systems, the north pole is defined to be the rotational pole in the northern celestial hemisphere. For planets with direct rotation, the angular momentum vector coincides with the north pole. For planets with retrograde rotation, the angular momentum vector coincides with the south pole. Target Position 69 Planetographic Coordinate System Table 4.5: Parameters for TYPE = PGRAPHIC LONG = <value> planetographic longitude in degrees, LAT = <value> planetographic latitude in degrees; + or – are required to denote north and south latitude, respectively, [ALT = <value>] planetographic altitude above the reference ellipsoid, in kilometers, [R_LONG = <value>]a rate of change of LONG, in degrees/day, [R_LAT = <value>]a rate of change of LAT, in degrees/day, [R_RAD = <value>]a rate of change of RAD, in kilometers/day, and [EPOCH = <value>] the reference time for the temporal variation, in UTC (4 digits). a. EPOCH must also be specified with this quantity. The PGRAPHIC TRS is the IAU planetographic coordinate system. It is a non-spherical coordinate system aligned with and rotating about the rotation axis of the Level 1 body, positive north, whose origin lies at the center of the reference body. Locations within this TRS are specified by longitude, latitude, and altitude above the surface. (The lambda(III) coordinate system defines the prime meridian in this coordinate system; if lambda(I) or lambda(II) coordinate systems are desired, note this in the Comments field.) Planetographic Latitude is defined as the angle between the equator and the normal to the surface of the reference ellipsoid at the point of interest. By definition, the planetographic longitude of the sub-Earth point increases with time. For planets with direct rotation, the planetographic longitude increases in a left-handed direction. For planets with retrograde rotation, the planetographic longitude increases in a right-handed direction. If ALT is omitted, then the surface of the reference ellipsoid is assumed. If the coordinates are constant in time, then none of the other optional entries should be used. If any coordinate is given as a function of time, then EPOCH is required and the time-varying coordinate is interpreted in the following way. Example: LONG = 20 LAT = -5 R_LONG = 45 EPOCH = 5-JAN-1990:15 For this example the longitude at any time, T, is given by: 70 Chapter 4: Solar System Targets List [Solar_System_Targets] longitude = LONG + R_LONG * (T – EPOCH) or, numerically, longitude = 20 + 45 * (t – 5–JAN–1990:00:15:00) The same interpretation for time-varying coordinates also applies to the other TRSs described below. Position Angle Coordinate System Table 4.6: Parameters for TYPE = POS_ANGLE RAD = <value> Radius, in arcseconds ANG = <value> Position angle relative to the reference axis, in degrees REF = NORTH REF = SUN Reference axis is celestial north, or Reference axis is the apparent direction to the Sun as projected on the sky, or User specified position angle of the reference measured in degrees eastward from north. REF = <value>a [R_RAD = <value>]a Rate of change of RAD, in arcseconds/sec [R_ANG = <value>]a Rate of change of ANG, in degrees/day [EPOCH = <value>] the reference time for the temporal variation, in UTC (4 digits). a. EPOCH must also be specified with this quantity. The POS_ANGLE TRS is a position-angle coordinate system (i.e. a two-dimensional polar-coordinate system). This TRS is useful for pointing at targets whose positions are known only in terms of an offset in projected celestial coordinates from another body. The origin of the system lies at the center of the Level 1 body. Locations are specified by giving the apparent distance from the origin (in projected celestial coordinates as viewed from the Earth) and the position angle from some reference axis to the target point. For REF = NORTH, angles are measured from celestial north (positive angles are measured in the same sense as rotating from celestial north through east). For REF = SUN, angles are measured from the direction to the Sun as projected on the sky (positive angles are measured in the same sense as rotating from celestial north through east). For REF = <value>, the proposer must specify the position angle of the reference axis, measured in degrees East of celestial north (once again, positive angles are measured in the same sense as rotating from celestial north through east). Target Position 71 Magnetic Coordinate System Table 4.7: Parameters for TYPE = MAGNETO LONG = <value> Magnetic longitude, in degrees LAT = <value> Magnetic latitude, in degrees; + or – are required to denote north and south latitude, respectively RAD = <value> Magnetic radius, in kilometers [POLE_LAT = <value>] Cartographic latitude of the pole, in degrees [POLE_LONG = <value>] Cartographic longitude of the pole, in degrees [O_LAT = <value>] Cartographic latitude of the origin in degrees; + or – are required to denote north and south latitude, respectively [O_LONG = <value>] Cartographic longitude of the origin in degrees [O_RAD = <value>] Cartographic radius of the origin, in kilometers The MAGNETO TRS is intended to support observations fixed with respect to a planetary magnetic field. It is a spherical coordinate system rotating with the Level 1 body around the rotation axis, with a specified offset of the coordinate origin and inclination of the coordinate pole. The MAGNETO coordinate system is defined in the following manner: • Define a “cartographic” reference frame identical to the planetographic TRS, except use spherical latitudes. • Rotate the new coordinate system relative to the cartographic frame so the new pole is located at POLE_LAT (latitude) and POLE_LONG (longitude). • The final step is to translate the origin of the new system to the specified cartographic latitude, longitude, and radius (O_LAT, O_LONG, and O_RAD, respectively). While the origin and coordinate axes may differ from those of the cartographic system, the rotation axis and rotation rate are identical to those of the cartographic system. Locations in the MAGNETO TRS are specified by longitude, latitude, and radius from the origin of the defined coordinate system. Torus Coordinate System Table 4.8: Parameters for TYPE = TORUS LONG = <value> Torus longitude, in degrees LAT = <value> Torus latitude, in degrees; + or – are required to denote north and south latitude, respectively 72 Chapter 4: Solar System Targets List [Solar_System_Targets] RAD = <value> Torus radius, in kilometers [POLE_LAT = <value>] Cartographic latitude of the pole, in degrees [POLE_LONG = <value>] Cartographic longitude of the pole, in degrees [O_LAT = <value>] Cartographic latitude of the origin in degrees; + or – are required to denote north and south latitude, respectively [O_LONG = <value>] Cartographic longitude of the origin in degrees [O_RAD = <value>] Cartographic radius of the origin, in kilometers If the optional fields above are left blank, the following default values are used: O_LONG = 0 O_LAT = +0 O_RAD = 0 POLE_LAT = +83 POLE_LONG = 202 The TORUS TRS is defined primarily to support observations of Jupiter’s plasma torus and is closely related to the MAGNETO TRS. TORUS is also useful for observers who want to observe in a coordinate system that is fixed relative to the apparent disk of the Level 1 body, e.g. central meridian observations (see special instructions below). The difference between the two systems is in the definition of the prime meridian. For the TORUS TRS, the prime meridian is defined by the instantaneous longitude of the sub-Earth point. Therefore, the TORUS TRS does not rotate with the Level 1 body. A typical observation would be of the east or west ansa (point of maximum elongation) of an equatorial circle whose radius is roughly five times the equatorial radius of Jupiter (in this case, LONG = 270 (90 for the west ansa), LAT = 0, RAD = 3.57E05). As the planet rotates, the target moves up and down in celestial coordinates as Jupiter rotates. This coordinate system can also be used to support observations of a planetary ring ansa. Special Instructions: The TORUS system can be useful for observations that want to remain fixed at a position of the observable disk of the Level 1 body rather than tracking a particular longitude. The most frequent example is observations on the central meridian at a specified latitude without regard to the longitude. To use TORUS in this way you must set the optional parameter POLE_LAT = +90. Target Position 73 Satellite Elements Coordinate System Table 4.9: Parameters for TYPE = SAT A = <value> Semi-major axis of satellite orbit, in km EPOCH = <value> Epoch of the elements, in TDB (4 digits) N = <value> Mean motion of satellite, in degrees/day L = <value> Mean longitude at EPOCH, in degrees [E = <value>] Eccentricity of satellite orbit [I = <value>] Inclination of satellite orbit to the planetary equator, in degrees [O = <value>] Longitude of ascending node of the satellite orbit, in degrees [W = <value>] Longitude of periapse, in degrees [O_RATE = <value>] Rate of change of longitude of ascending node, in degrees/day [W_RATE = <value>] Rate of change of periapse, in degrees/day [RAP = <value>] Right Ascension of the parent planet pole at EPOCH [DECP = <value>] Declination of the parent planet pole at EPOCH [EQUINOX = <value>] B1950 or J2000 When the target is a satellite of the object defined in the Level 1 field, but the satellite itself is not among the standard objects, then orbital elements must be specified. These elements refer to the motion of the satellite around the Level 1 object. The “reference” axis for the angles defined above is the intersection of the Earth’s equator at the standard epoch implied by the EQUINOX with the parent planet’s equator at the EPOCH of the elements. The positive X-axis for the coordinate system used in the orbit calculation is obtained by taking the cross product of the Z-axis of the standard system (i.e. the system defined by the standard equator and equinox given by EQUINOX) with the pole of the planet. If E, I, O, W, O_RATE, and W_RATE are not supplied, then their values are assumed to be 0. If RAP and DECP are not supplied, then the standard IAU values are used. If RAP and DECP are supplied, then they should be referred to the standard equator and equinox given by EQUINOX. If EQUINOX is not provided, we will assume J2000. STScI maintains its ephemeris data base with the best available elements, and you should use the STD = form for objects in Table 4.1: Solar System Standard Targets unless there is compelling scientific justification for specifying orbital elements. Note: It is the responsibility of the observer to supply accurate orbital elements to STScI when specifying TYPE=SAT. 74 Chapter 4: Solar System Targets List [Solar_System_Targets] Planetocentric Coordinates (Available but Unsupported) An additional TRS, PCENTRIC, is available for engineering users. PCENTRIC: planetocentric coordinates relative to Level 1 target For the PCENTRIC coordinate system, the north pole is defined to be the rotational pole in the northern celestial hemisphere. For planets with direct rotation, the angular momentum vector coincides with the north pole. For planets with retrograde rotation, the angular momentum vector coincides with the south pole. Table 4.10: Parameters for TYPE = PCENTRIC (Available but Unsupported) LONG = <value> planetocentric longitude in degrees, LAT = <value> planetocentric latitude in degrees; + or – are required to denote north and south latitude, respectively, [RAD = <value>] planetocentric radius in kilometers, [R_LONG = <value>]a rate of change of LONG, in degrees/day, [R_LAT = <value>]a rate of change of LAT, in degrees/day, [R_RAD = <value>]a rate of change of RAD, in kilometers/day, and [EPOCH = <value>] the reference time for the temporal variation, in UTC (4 digits). a. EPOCH must also be specified with this quantity. The PCENTRIC TRS is the IAU planetocentric coordinate system. It is a right-handed spherical coordinate system aligned with and rotating about the rotation axis of the Level 1 body, positive north, whose origin lies at the center of the Level 1 body. Locations within this TRS are specified by longitude, latitude, and radius from the origin. (The lambda(III) coordinate system defines the prime meridian in this coordinate system; if lambda(I) or lambda(II) coordinate systems are desired, note this in the Comments field.) Planetocentric longitude increases in a right-handed direction for all planets. For planets with direct rotation, the planetocentric longitude of the sub-Earth point does not increase with time. If RAD is omitted, then RAD is assumed to be the equatorial radius of the Level 1 body. Note that in general, if RAD is omitted, the point specified will not necessarily be on the visible surface of the planet. This is of special concern for oblate planets, e.g. Jupiter and Saturn, where a point at high latitude at the equatorial radius can appear above the limb of the planet in projection. When using this coordinate system for surface features on Jovian planets, it is best to specify the radius explicitly. Ephemeris Uncertainty [Ephem_Uncert] 75 For spherical planets, planetographic and planetocentric latitudes are identical. For significantly nonspherical objects, there is no simple conversion between the two latitude systems. For planets with retrograde rotation, the planetocentric and planetographic longitudes of a point are identical. For planets with direct rotation, the planetocentric and planetographic longitudes of a point have opposite sign. Target Position Level 3 [Level_3] The instructions for this field are identical to those for the Level 2 field except that “Level 3” should be substituted wherever “Level 2” occurs, and “Level 2” should be substituted wherever “Level 1” occurs. Ephemeris Uncertainty [Ephem_Uncert] The <value> for ephemeris uncertainty is the distance along its trajectory that the target is expected to be from its ephemeris position, in kilometers (KM), or seconds of time (S). The latter reflects the fact that in general, the least well known parameter in an ephemeris is the perihelion time. This parameter is required for any moving target used in an exposure with the REQuires EPHEMeris CORRection Special Requirement (see REQuires EPHEMeris CORRection <id>). Note: A realistic estimate of ephemeris uncertainty is needed to schedule the time necessary to repoint the telescope to the improved position when it is known. It will not be possible for STScI to apply a correction larger than the specified uncertainty. Acquisition Uncertainty [Acq_Uncert] The <value> for acquisition uncertainty is the uncertainty in the position of the target in a direction perpendicular to the line of sight, in kilometers (KM) or arcsec ("). This parameter is required for any moving target used in an exposure with the USE OFFSET <id> (Available but Unsupported) Special Requirement (see Target Acquisition on page 7-134). Note that there will have to be an exposure of the acquisition target with a corresponding SAVE OFFSET <id> (Available but Unsupported) Special Requirement. (There is no need for this keyword when observing fixed targets, because the specified target uncertainty is used). 76 Chapter 4: Solar System Targets List [Solar_System_Targets] Note: A realistic estimate of acquisition uncertainty is needed to schedule the time necessary to repoint the telescope to the improved position when it is known. It will not be possible for STScI to apply a correction larger than the specified uncertainty. Observing Windows [Window] The observability of solar system targets is often constrained by various geometrical conditions (e.g. satellites observed at greatest elongation from their parent planet), or the desirability of coordinated observations (e.g. the observation of a planetary system at the same time as a spacecraft encounter with the system). The Window field is provided to allow the proposer to define geometric and timing constraints. The proposer should specify any constraints necessary to achieve the scientific objectives of the program. However, care should be taken in specifying constraints, since they can render the observations difficult or impossible to schedule. In general, “windows” which define when the target is visible to HST need not be explicitly identified, since these windows will be calculated by the STScI. Windows in this category include: • Times when the target is not occulted by the Earth. • Times when the target is not too close to the Sun, Moon, or the bright Earth limb. • If the target is a planetary satellite, the times when it is not occulted by any other object in the planetary system. • If the target is a surface feature on a body, the times when the feature is within the field of view of the HST (i.e. the feature is on that part of the body “facing” HST). If you require other specific conditions to be satisfied (e.g. to observe when a satellite is near elongation, to observe when the central meridian longitude lies in a particular range, etc.), then these conditions must be specified in the Window field. However, the proposer must recognize that proposer-supplied windows might not overlap with the “visibility” windows defined above (calculated by STScI), in which case the observation cannot be scheduled. Note that atmospheric drag and other effects make it difficult to predict the exact position of the HST in its orbit far in advance. This leads to uncertainty in the exact timing of the “visibility” windows more than two or three months in advance. The various keywords used to define windows are given in the following table and described in detail below. Observing Windows [Window] 77 Table 4.11: Keywords for Observing Windows SEP angular separation of two bodies as viewed from a third body RANGE distance between two bodies in AU A_VEL angular velocity in arcsec/sec R_VEL radial velocity of one body relative to another in km/sec SIZE angular diameter of one body as seen from another in arc-sec PHASE phase of one body as seen from another OCC when two bodies overlap as viewed from a third body TRANSIT when one body crosses another as viewed from a third body ECL when one body is in the shadow of another body CML central meridian longitude OLG orbital longitude Table 4.12: Operators for Observing Windows LT short for less than GT short for greater than EQ short for equals MAX short for maximum MIN short for minimum. NOT logical complement. May be used to specify when a condition does not exist. Each of the above keywords may be preceded by the NOT operator. The operator NOT, if present, should precede the keyword for the solar system target observing window, as in these examples: NOT SEP OF IO JUPITER FROM EARTH GT 10 NOT RANGE JUPITER EARTH GT 10 NOT A_VEL IO RELATIVE JUPITER FROM EARTH GT 10 SEP SEP is short for “Separation” and is used to find the times when the apparent separation between two objects, as observed from a third object, satisfies certain conditions. The separation between two bodies is defined as the angle between the closest points on the observed limbs of the spheres representing the objects as viewed from the observer (the radius of the 78 Chapter 4: Solar System Targets List [Solar_System_Targets] sphere is equal to the largest radius of the tri-axial ellipsoid representation of the object). The syntax is: [NOT] SEP OF <object 1> <object 2> FROM <observer><condition> <angle> where <object 1>, <object 2>, and <observer> must either be standard bodies, or objects that have been previously defined in the target position fields. The unit for “angle” must be chosen from one of D (degrees), ' (arc-minutes), or " (arc-seconds). The interpretation of the SEP keyword is as follows. When the <condition> is either LT, GT, or EQ then times are found when the separation of “objects 1 and 2”, as viewed from <observer>, is less than <angle>, is greater than <angle>, or equals <angle>, respectively. When the <condition> is MAX (MIN), then times are found when “objects 1 and 2” are at maximum elongation (minimum separation), as viewed from <observer>. RANGE RANGE is used to select windows based on the separation of objects in terms of distance (AU). The syntax is: [NOT] RANGE <object 1> <object 2> <condition> <distance> A_VEL A_VEL is used to select windows based on the angular velocity of objects in terms of arcsec/sec. The syntax is: [NOT] A_VEL <object 1> [RELATIVE <object 2>] FROM <object 3> <condition> <velocity> <Velocity> is the angular velocity of <object 1> as observed from <object 3>. If RELATIVE is used, <velocity> is the apparent angular velocity of <object 1> relative to <object 2> as observed from <object 3>. R_VEL R_VEL is used to select windows based on the change in distance between two objects (i.e. the Radial Velocity) in km/sec. The syntax is: [NOT] R_VEL <object 1> <object 2> <condition> <velocity> Positive values of <velocity> mean that the objects are moving away from each other while negative values mean that the objects are moving closer to each other. Observing Windows [Window] 79 SIZE SIZE is used to select windows based on the apparent angular diameter of an object in arc-seconds. The syntax is: [NOT] SIZE <object> <condition> <angle> PHASE PHASE is used for solar phase angle, and is used to find times when the angular phase of one body as seen from another is within a specified range. The syntax is: [NOT] PHASE OF <object> FROM <observer> BETWEEN <angle 1> <angle 2> where <angle> is the observer-object-sun angle, in degrees. OCC OCC is short for “Occultation” and is used to find times when one body appears to pass behind another body as viewed from a third body. The syntax is: [NOT] OCC OF <occulted object> BY <occulting object> FROM <observer> The <occulted object>, <occulting object>, and <observer> must be standard bodies from Table 4.1: Solar System Standard Targets. An occultation is defined to begin when the limb of the sphere representing the <occulted object> first touches the limb of the sphere representing the <occulting object>, as seen from the vantage point of the <observer>. TRANSIT TRANSIT is used to find times when one body appears to pass across the disk of another body as viewed from a third body. The syntax is: [NOT] TRANSIT OF <transiting object> ACROSS <transited object> FROM <observer> The <transiting object>, <transited object>, and <observer> must be standard bodies from Table 4.1: Solar System Standard Targets. A transit is defined to begin when the disk representing the <transiting object> is entirely in front of the disk representing the <transited object>, as seen from the vantage point of the <observer>. The transit ends when the limbs of the two disks come into contact again. Thus at any time in the transit the <transiting object> is entirely surrounded by the <transited object>. 80 Chapter 4: Solar System Targets List [Solar_System_Targets] ECL ECL is short for “Eclipse” and is used to find times when one body is in the shadow (cast in sunlight) of another body. The syntax is: [NOT] ECL <type> OF <eclipsed object> BY <eclipsing object> The <eclipsed object> and <eclipsing object> must be standard bodies from Table 4.1. An eclipse is defined to begin when the trailing limb of the <eclipsed object> enters the penumbra (<type> = P) or the umbra (<type> = U) of the <eclipsing object>. An eclipse is defined to end when the leading limb of the <eclipsed object> exits the penumbra (<type> = P) or the umbra (<type> = U) of the <eclipsing object>. One of the values P or U must be specified. CML CML is short for “Central Meridian Longitude” and is used to find times when the sub-observer meridian of an object lies within a particular range. The syntax is: [NOT] CML OF <object> FROM <observer> BETWEEN <angle 1> <angle 2> The <object> and <observer> must be standard bodies from Table 4.1: Solar System Standard Targets. The keyword specifies those times when the central meridian longitude lies between <angle 1> and <angle 2> (both in degrees) as seen by the <observer>. OLG OLG is short for “Orbital Longitude” and is used to select observation times based on a geocentric view (usually) of the object. OLG can be used on either a Level 1 or a Level 2 object. The syntax is: [NOT] OLG OF <object 1> [FROM <object 2>] BETWEEN <angle 1> <angle 2> where <angle 1> and <angle 2> are in degrees. OLG specifies those times when the orbital longitude lies between <angle 1> and <angle 2>. The default for <object 2> is the Earth. If <object 1> refers to a Level 2 body, usually a satellite, the orbital longitude is defined as follows (see Figure 4.1 Orbital Longitude for Satellites): 1. Construct a vector from <object 2> (Earth) to the Level 1 parent (planet) of the <object 1> (satellite). 2. Extend the vector “behind” the planet and project it onto the orbital plane of the satellite. This is the reference axis. 3. The orbital longitude is the angle from the reference axis to the position of the satellite measured in the direction of motion of the satel- Observing Windows [Window] 81 lite. Valid values for the orbital longitude lie in the range 0–360 degrees. Orbital Longitude of 0 degrees corresponds to superior conjunction, Orbital Longitude of 180 degrees corresponds to inferior conjunction, and 90 degrees and 270 degrees correspond to greatest eastern and western elongation, respectively. If “object 1” refers to a Level 1 body, e.g. a planet, asteroid, or comet, the orbital longitude is defined to be the angle between the Sun-Earth vector and the Sun-Planet vector, projected onto the planet’s orbital plane, increasing in the direction of the planet’s orbital motion (see Figure 4.2: Orbital Longitude for Planets). Orbital Longitude of 0 degrees corresponds to opposition, Orbital Longitude of 180 degrees corresponds to conjunction with the Sun. However, Orbital Longitude of 90 degrees or 270 degrees does not correspond with quadrature. Orbital Longitude is not synonymous with “elongation” or “separation” from the sun. Default Target Windows Please note that the following defaults apply for solar system targets: All targets: SEP OF <target> SUN FROM EARTH GT 50D All targets in the Martian system except Mars: SEP OF <target> MARS FROM EARTH GT 10" All targets in the Jovian system except Jupiter: SEP OF <target> JUPITER FROM EARTH GT 30" All targets in the Jovian system except Io: SEP OF <target> IO FROM EARTH GT 10" All targets in the Jovian system except Europa: SEP OF <target> EUROPA FROM EARTH GT 10" All targets in the Jovian system except Ganymede: SEP OF <target> GANYMEDE FROM EARTH GT 10" All targets in the Jovian system except Callisto: SEP OF <target> CALLISTO FROM EARTH GT 10" All targets in the Saturnian system except Saturn: SEP OF <target> SATURN FROM EARTH GT 45" 82 Chapter 4: Solar System Targets List [Solar_System_Targets] All targets in the Saturnian system except Rhea: SEP OF <target> RHEA FROM EARTH GT 10" All targets in the Saturnian system except Titan: SEP OF <target> TITAN FROM EARTH GT 10" All targets in the Uranian system except Uranus: NOT OCC OF <target> BY URANUS FROM EARTH All targets in the Neptunian system except Neptune: NOT OCC OF <target> BY NEPTUNE FROM EARTH All TYPE=PGRAPHIC,TYPE=PCENTRIC, and TYPE=MAGNETIC targets: NOT OCC OF <target> BY <parent body> FROM EARTH These default windows will be superseded by any similar windows specified in the solar system target list. For example, if the target is Io and an Io-Callisto separation window is specified by the observer, then the observer’s Io-Callisto separation window will apply and the default will not. Flux Data [Flux] Flux information for all targets is required. There can be more than one entry for a given target. STScI will use this flux information to prevent over-illumination of sensitive detectors. Proposers should refer to Flux Data [Flux] on page 3-49for instructions and guidelines on how to provide flux data for their targets. The flux data must be given in the format and units shown in Table 4.13: Formats for Specification of Target Flux Data. The units should not be entered on the Target List. Flux Data [Flux] 83 Table 4.13: Formats for Specification of Target Flux Data Parameter Format example Units Broad-band magnitudea V=13.1 +/– 0.5 magnitude Spectral type TYPE=G5III Color Indexa B-V = 0.86 +/– 0.2 magnitude Color Excess E(B-V) = 0.3 +/– 0.2 magnitude Background Surface Brightnessb SURF-BKG(B) = 20 +/– 0.2 mag/arcsec2 Examples for Stars: Examples for Galaxies, Nebulae, and other extended sources: Surface Brightnessa,b SURF(V) = 25.0 +/– 1.0 mag/arcsec2 Surface Brightnessa SURF(B) = 24.5 +/- 0.5 mag/arcsec2 Color Excess E(B-V) = 2.5 +/– 0.2 mag Plus whatever other fluxes are relevant to your science program. Some other examples are listed below: Interstellar Extinction A(V) = 1.3 +/– 0.1 mag Flux at a specified wavelength F(5100) = 51 +/– 3 E-15 erg/(cm2 sec Å) Continuum Fluxc F-CONT(3500) = 57 +/– 3 E-15 erg/(cm2 sec Å) Line Fluxc,d,e F-LINE(3727) = 5 +/– 1 E-14 erg/(cm2 sec Å) Line Widthf W-LINE(3727) = 2.4 +/– 0.2 Å Surface Brightness at specified wavelengthb SURF(5100) = 11 +/– 2 E-15 erg/(cm2 sec Å arcsec^2) Surface Brightness at continuum wavelengthb SURF-CONT(5000) = 52 +/– 2 E-15 erg/(cm2 sec Å arcsec^2) Surface Brightness of line emissionc,d,e SURF-LINE(5007) = 52 +/– 2 E-15 erg/(cm2 sec arcsec^2) Size (FWHM of circular region)g SIZE = 25 +/–5 arcsec a. The following broad-band magnitudes may be used: U,B,V,R,I,J,H,K. b. You may append “–BKG” to this reference (just before the wavelength designation) to indicate that it is a background flux value (e.g., SURF-BKG(V) = 18.2 +/– 0.5; SURF-CONT-BKG(5100) = 10 +/– 3 E-15). c. Give wavelength used in keyword in rest frame, but flux in observed frame. d. Line flux should be relative to the continuum, if specified, or relative to zero if not specified. e. Whenever the S/N refers to a spectral line, W-LINE must be given along with F-LINE or SURF-LINE. Values of F-LINE and SURF-LINE outside the Earth’s atmosphere are required. 84 Chapter 4: Solar System Targets List [Solar_System_Targets] f. W-LINE is the full width at half maximum (FWHM). g. SIZE should be included if the exposure time estimate assumed the flux was spread over an extended region; if omitted, the highest spatial resolution of the observing mode will be assumed. Comments [Comments] This field should include in words what you are trying to define by coordinates and windows in the other fields. For example, for Target No. 3 on the sample form the TPS and Window fields define mathematically the location of the target and the valid observation times, but the Comments field is probably much more useful in helping an observation planner determine the proposer’s objectives. Use only alphanumeric characters and hyphens. Illustrations of Orbital Longitude Figure 4.1: Orbital Longitude for Satellites Planet OLG Satellite Earth Examples of Target List Blocks 85 Figure 4.2: Orbital Longitude for Planets Sun Earth OLG Planet Examples of Target List Blocks The sample targets defined in this section are provided as examples of completed blocks using the syntax described in these instructions. This collection does not provide an example for every type of keyword but does give a good overall representation of the types of target selections that can be accommodated. Numerical data in these examples is fictional. • Example 1: In this example the proposer wants to perform spectroscopy of a volcano on Io. The position of the target is given in planetographic coordinates. The proposer also wants to observe the target when it lies close to the central meridian and, thus, uses CML to specify the allowable range of the central meridian longitude. Target_Number: Target_Name: Description: Level_1: Level_2: Level_3: Window: Flux: Comments: 1 IO-VOLCANO FEATURE IO STD = JUPITER STD = IO TYPE = PGRAPHIC, LONG = 310, LAT = 13 CML OF IO FROM EARTH BETWEEN 280 340 SURF(V) = 5 +/– 0.5, SURF-CONT(2300) = 5.2 +/– 0.2 E–14, SIZE = 1.0 Observe IO volcano Loki when it is near the central meridian. 86 Chapter 4: Solar System Targets List [Solar_System_Targets] • Example 2: In this example the proposer wants to perform spectroscopy of the western ansa of the Io torus when Io is near greatest eastern elongation. The elongation condition is specified using the OLG keyword. Target_Number: Target_Name: Description: Level_1: Level_2: Window: Flux: Comments: 2 IO-TORUS TORUS JUPITER STD = JUPITER TYPE = TORUS, LONG = 90, LAT = 0, RAD = 4.3E5 OLG OF IO BETWEEN 90 100 SURF-LINE(1304) = 1 +/– 0.5E–13, W-LINE(1304) = 2 +/– 1, SIZE = 1 West ansa of IO Torus when IO is at greatest eastern elongation. • Example 3: In this example the proposer wants to perform spectroscopy in the tail of comet Halley near the time of the Giotto spacecraft encounter. The latest orbital elements for the comet have been supplied by the proposer and these will be used for the ephemeris generation. The POS_ANGLE target reference system is used to specify the tailward pointing. Target_Number: Target_Name: Description: Level_1: Level_2: 3 COMET-HALLEY-TAIL OFFSET COMET HALLEY TYPE = COMET, Q = 0.5871167, E = 0.9672815, I = 162.2397156, O = 58.144397, W = 111.8489075, T = 09-FEB-86:11:01:04, EPOCH = 01-MAR-86, EQUINOX=B1950 TYPE = POS_ANGLE, RAD = 30, ANG = 180, Examples of Target List Blocks Flux: Comments: 87 REF = SUN SURF(V) = 12 +/– 1, SURF-LINE(1216) = 3.1 +/– 0.5E10, W-LINE(1216) = 0.1 +/– 0.5, SIZE = 1 30 arcsec into tail of Halley during Giotto encounter. New orbital elements based on recent observations are provided. 88 Chapter 4: Solar System Targets List [Solar_System_Targets] CHAPTER 5: Visits and Exposures For an explanation of this engineering-only version, see Special Note to Engineering Version Users in Chapter 1: About This Document on page 3. In this chapter . . . Visit Number [Visit_Number] / 91 Visit Priority [Visit_Priority] / 91 Visit-level Special Requirements [Visit_Requirements] / 92 On Hold Comments [On_Hold_Comments] / 92 Visit Comments [Visit_Comments] / 93 Exposure Number [Exposure_Number] / 93 Target Name [Target_Name] / 93 Operating Mode [Opmode] / 96 Aperture or Field of View [Aperture] / 96 Spectral Element [Sp_Element] / 97 Central Wavelength or Range if Grating or Prism Used [Wavelength] / 97 Optional Parameters [Optional_Parameters] / 98 Number of Times to Iterate the Exposure [Number_of_Iterations] / 98 Time per Exposure [Time_Per_Exposure] / 98 Exposure-level Special Requirements [Special_Requirements] / 100 Exposure-level Comments [Comments] / 100 89 90 Chapter 5: Visits and Exposures Tables and Figures Table 5.1: Internal Calibration Target Names Table 5.1: Internal Calibration Target Names (Limited Access) Table 5.2: Special External Target Names Table 5.3: Instrument Configurations and Operating Modes Table 5.3: Instrument Configs and Operating Modes (Limited Access) Table 5.4: Aperture and Field of View Names Table 5.4: Aperture and Field of View Names (Restricted) The Visit and Exposure Specifications are used to define the proposed exposures for all the Scientific Instruments. While the number of parameters needed to define all possible instrument configurations is large, the Visit and Exposure Specifications has been simplified by using standard Instrument Configurations and Operating Modes to set most of the instrument parameters to default values. The rest of the exposure keywords are used to define parameters that usually change from one exposure to the next, such as filters, exposure times, and special scheduling requirements. Before proceeding further, it is useful to define more carefully what is meant by an exposure and by a visit. An exposure consists of the events and data corresponding to a unique Exposure_Number in the RPS2 file within a given visit. The full description of an exposure is often called “the Exposure line”, although in the RPS2 template it takes several lines to describe an exposure. Here we have adopted Exposure Specification as a term for this. Although many data samples (images or spectra) may result from a single execution of an Exposure Spec (due to the Instrument Configuration, Operating Mode, and Optional Parameters chosen), they are considered to be one exposure. The observer may specify multiple exposures on one exposure line by entering an integer greater than 1 for the Number_of_Iterations keyword (see Number of Times to Iterate the Exposure [Number_of_Iterations] on page 98), and these exposures will be obtained consecutively (except for possible interruptions by Earth occultations, guide star acquisitions, and SAA passages). Exposures defined within a visit will be obtained consecutively and in the order specified within that visit. A visit is an exposure or series of consecutive exposures, with overheads, on a given target, and may consist of the following parts: 1. Guide-star acquisition (to point HST at the target) 2. Target acquisition (to place the target in an instrument aperture) 3. Science exposure(s) (to obtain the data) Visit Number [Visit_Number] 91 4. Instrument overheads (to set up the instrument and read out the data) 5. Instrument calibrations (if more than the standard calibration is required) If the visit lasts more than one orbit, it will continue with the following for each subsequent orbit: 6. Guide-star re-acquisition (to keep HST pointed and locked after Earth occultations) 7. Science exposure(s) 8. Instrument overheads 9. Instrument calibrations Whenever one of the following occurs, a new visit must be defined: 1. A change in target position of greater than 1 degree. (Contact your Program Coordinator for details regarding solar system objects that move more than about 30 arcsec during the observation and thus are likely to require multiple sets of guide stars). 2. Repeated, periodic, or other time-separated observations with an interval between exposures such that one or more empty visibility periods (orbits with no exposures) would otherwise be required. 3. Required change in spacecraft roll orientation. Visit Number [Visit_Number] Visit numbers provide a method for unique labeling of visits. The visit number should be a positive integer between 1 and 99. If you have more than 99 visits in your program, please contact your Program Coordinator. (Visit numbers are actually base 36 values ranging from 01 - ZZ.) Visit Priority [Visit_Priority] This field is required for visits in pure parallel proposals (those with a Proposal_Category ending in /PAR). This field does not apply to primary exposures or proposals. The priority should be a positive integer between 1 and 999. This is a number giving the scheduling priority for the given parallel visit, with higher numbers having higher priority. If a primary pointing matches the target of two or more visits in a parallel proposal, the system will schedule the highest-priority parallel visit that will fit into the opportunity. Therefore, to allow maximum use of long opportunities, visits 92 Chapter 5: Visits and Exposures designed for longer opportunities should have higher priority. No two parallel visits in a proposal should have the same priority. Visit-level Special Requirements [Visit_Requirements] A variety of visit-level Special Requirements may be entered; these requirements apply to all exposures in the visit (exposure-level Special Requirements are discussed in Chapter 7: Special Requirements [Visit_Requirements and Special_Requirements] on page 111). These requirements will be interpreted by the computer software that is used to schedule the observations; therefore it is absolutely essential that the specific formats shown in Chapter 7: Special Requirements [Visit_Requirements and Special_Requirements] on page 111 are followed precisely. If none of the allowed Special Requirements appears to be sufficient, it is permissible to describe the requirements with a text explanation using the Visit_Comments keyword. You should contact your Program Coordinator prior to entering such a comment in your proposal. Several of these Special Requirements require the use of limited resources or may impose serious constraints on the scheduling system (e.g., ORIENT, CVZ, BETWEEN). These Special Requirements should be used with care. The visit-level Special Requirements are described in detail in Chapter 7: Special Requirements [Visit_Requirements and Special_Requirements] on page 111. If more than one Special Requirement is needed for a visit, they should be separated by a space, carriage return, or semi-colon, but not by a comma. On Hold Comments [On_Hold_Comments] If you have requested via the Special Requirement ON HOLD that a given visit be placed “on hold” (which means that the visit will not be scheduled until you have cleared the hold), then indicate why the visit is on hold, and how the hold is to be released. Examples of On_Hold_Comments are: • Target of Opportunity • Waiting for Early Acquisition data from visit <number> • Waiting for non-HST data [to be obtained <date>] • Conditional if <text> Visit Comments [Visit_Comments] 93 • Conditional on <exposure-list> if <text> • Select <number> of <exposure-list> Visit Comments [Visit_Comments] Information that cannot be made to conform to the required formats may be entered as a comment. Comment lines are not interpreted by the software, but are maintained in the database and do appear on printouts of the programs. Please contact your Program Coordinator prior to inserting comments to make certain there is no other way to specify the information. An Example of a Visit_Comments is: • Early Acquisition for visit 13 Exposure Number [Exposure_Number] Exposure numbers provide a method for unique labeling of exposures within a visit. The line numbers must be positive, monotonically increasing (but not necessarily consecutive) unique integers; floating-point numbers are not allowed. The smallest exposure number permitted is 1, and the largest is 999. Note that exposure numbers for coordinated parallels must be sequential; see Coordinated Parallels on page 105. Target Name [Target_Name] Normally, the name of an astronomical target from the Target List should be entered. In the case of certain internal calibration sources, a special code must be entered. In general, calibration observations will be requested only rarely, since most calibrations will be carried out by STScI (see the Call for Proposals). Due to scheduling constraints, fixed external targets and solar system targets may not be used in the same visit. Also, none of the external calibration targets (EARTH-CALIB, ANTI-SUN, ORBIT-POLE-NORTH, ORBIT-POLE-SOUTH) may be used in the same visit with another external target. 94 Chapter 5: Visits and Exposures Astronomical Targets The target name should be entered exactly as it appears in the Target List (see Target Name [Target_Name and Alternate_Names] on page 25). Only the prime target name (Target_Name) should be used; do not use the alternate names (Alternate_Names). Special Targets If an internal calibration observation is requested on the Visit and Exposure Specifications, one of the specific “target” names in Table 5.1 must be entered. The calibration source should not be entered in the Target List. See the Call for Proposals for discussions of the routine calibrations that will be performed by STScI. See the Instrument Handbooks for further details of the calibrations for each instrument. Table 5.1: Internal Calibration Target Names STIS WAVE CCDFLAT Table 5.1 (cont): Internal Calibration Target Names (Limited Access) WFPC2 NICMOS (Restricted) STIS FGS BIAS DARK KSPOTS INTFLAT UVFLAT VISFLAT NONE DARK NONE BIAS DARK NONE DARK (POS mode only) The special external targets listed in Table 5.2 may be specified in the Target_Name without including them in the Target List. Instrument Configuration [Config] 95 Table 5.2: Special External Target Names Name Description EARTH-CALIB The sunlit Earth is used for a flat-field calibration. EARTH–CALIB may not be used in the STIS/FUV–MAMA and STIS/NUV–MAMA configurations, because of bright object constraints. Target will be nearly opposite the Sun whenever scheduled. Target will be the North orbit pole. ANTI-SUN ORBIT-POLE or ORBIT-POLE-NORTH ORBIT-POLE-SOUTH ANY Target will be the South orbit pole Allowed on pure-parallel and coordinated-parallel exposures. The target will be wherever the parallel aperture happens to point. Specific astronomical objects used as external calibrators (e.g., standard stars) should be entered in the Target List and Visit and Exposure Specifications as normal exposures, and the suffix -CALIB should be appended to their names, as discussed in Special Targets on page 29. Instrument Configuration [Config] Enter the Instrument Configuration to be used. The available choices are listed in Table 5.3, along with the corresponding Operating Modes that may be entered in “Opmode” (see Operating Mode [Opmode] on page 96). Legal Apertures, Spectral Elements, and Optional Parameters are uniquely determined by the choice of the Instrument Configuration and Operating Mode. Detailed descriptions are provided in Part B of these Instructions and the Instrument Handbooks. Table 5.3: Instrument Configurations and Operating Modes Instrument Configuration WFPC2 STIS/CCD STIS/FUV–MAMA or STIS/NUV–MAMA FGS Operating Modes IMAGE ACQ, ACQ/PEAK, ACCUM ACCUM, TIME–TAG POS, TRANS 96 Chapter 5: Visits and Exposures Table 5.3 (cont): Instrument Configs and Operating Modes (Limited Access) Instrument Configuration Operating Modes WFPC2 (Restricted) DECON (Restricted), POM (Restricted), AFM (Restricted) ACCUM, MULTIACCUM BRIGHTOBJ ALIGN (Restricted) ACQ ALIGN (Restricted), ANNEAL (Restricted) WALKDOWN, LOS, MAP NIC1 or NIC2 or NIC3 (Restricted) NIC1 or NIC2 or NIC3 (Restricted) NIC1 or NIC2 or NIC3 (Restricted) NIC2 (Restricted) STIS (Restricted) FGS Operating Mode [Opmode] Enter the Operating Mode to be used. Table 5.3 lists all possibilities. See the Instrument Handbooks for a detailed discussion of each Operating Mode. Aperture or Field of View [Aperture] The desired aperture or field of view of the Scientific Instrument should be entered as defined in Table 5.4 below. However, observers are cautioned that not all combinations of Apertures, Operating Modes, and Spectral Elements are available. See the Instrument Handbooks for details. Table 5.4: Aperture and Field of View Names WFPC2 STIS FGS Wide variety of FOVs are available; refer to Chapter 9: Wide Field Planetary Camera 2 (WFPC2) on page 179 See Chapter 10: Space Telescope Imaging Spectrograp h (STIS) on page 199 PRIME 1 2 3 Spectral Element [Sp_Element] 97 Table 5.4 (cont): Aperture and Field of View Names (Restricted) NICMOS (Restricted) NIC1, NIC1–FIX, NIC2, NIC2–ACQ, NIC2–CORON, NIC2–FIX, NIC3, NIC3–FIX There are numerous additional Available but Unsupported slits. See the STIS Instrument Handbook for details. Also see Appendix A to the STIS Instrument Handbook, which is available on the WWW at Spectral Element [Sp_Element] The desired Spectral Element(s) should be entered. Spectral Elements include filters (F), gratings and grisms (G), echelles (E), prisms (PRISM), polarizers (POL), and mirrors (MIRROR). The names of the filters, gratings, grisms, and echelles include the wavelength of the approximate midpoint of the bandpass, in nanometers (except tens of nanometers for NICMOS elements). More than one element may be specified, if necessary, using a comma to separate them (after confirming that the different elements can be used simultaneously, e.g., that they are not on the same filter wheel). Possibilities are listed in Part B of these Instructions and are described in the Instrument Handbooks. Examples of the Spectral Element designations are the following: F122M G140L G206 E230H POLQN33 A medium-band (M) WFPC2 filter (F) with midpoint of coverage near 1220 Å A low-dispersion (L) STIS grating (G) with midpoint of coverage near 1400 Å A NICMOS grism (G) with midpoint of coverage near 2.06 microns A high-dispersion (H) STIS echelle (E) with midpoint of coverage near 2300 Å WFPC2 polarizer at 33 degree angle Central Wavelength or Range if Grating or Prism Used [Wavelength] If a linear ramp filter, quadrant filter, grating, or prism is to be used, the central wavelength should be entered. NICMOS exposures do not require a central wavelength or range. 98 Chapter 5: Visits and Exposures Wavelengths should be expressed in Å in the observed frame (but the units should be omitted). Use vacuum wavelengths below 2000 Å, and air wavelengths above 2000 Å. For STIS exposures, the central wavelength must obey one of the legal spectral element/wavelength combinations given in Table 10.2: Supported Central Wavelengths for STIS Gratings. Optional Parameters [Optional_Parameters] The Operating Modes of the instruments frequently have parameters that may be adjusted. The default parameter values that have been defined for the various Instrument Configurations and Operating Modes can be overridden by entries in Optional Parameters. See the instrument chapters in this document and the Instrument Handbooks for descriptions of the Optional Parameters. If more than one Optional Parameter is entered, they can be separated by commas. The format that should be used is <parameter> = <value> (for example, BINAXIS1=1, BINAXIS2=1). If no entry is made, the default value will be used (e.g., BINAXIS1=1 would be used in STIS/CCD ACCUM Mode; see “Mode = ACCUM Config = STIS/CCD” on page 210). Number of Times to Iterate the Exposure [Number_of_Iterations] Enter the number of times the defined exposure is to be iterated; enter 1 if only one execution of the exposure is desired. Typical reasons for iterating an exposure are to monitor temporal changes in a target or to keep CCD exposures short to minimize blooming by a bright star. If more than one execution is requested, the iterations will be obtained in a contiguous fashion. Also note that for STIS, these iterations can be interrupted by an autowavecal. The autowavecal can be suppressed; see SEQuence <exposure-list> NON-INTerruptible. Time per Exposure [Time_Per_Exposure] Enter the exposure time for each separate exposure, using units of either hours (H), minutes (M), or seconds (S). Do not combine H, M, and S on Time per Exposure [Time_Per_Exposure] 99 the same line (i.e., use 90M rather than 1H 30M). It is important that observers consult the Instrument Handbooks, and the tools on the STScI web pages. Note that the exposure time is the total time for one execution of a defined exposure. Multiple executions may be specified by entering a value for Number_of_Iterations (see “Number of Times to Iterate the Exposure [Number_of_Iterations]” on page 98), or with certain Special Requirements. The exposure time entered may be divided among many subexposures, samples, or spectra, depending on the Instrument Configuration, Operating Mode, and Optional Parameters. Generally, the exposure time is used only for the collection of photons, but there are exceptions for which instrumental overheads are included in the exposure time. For details, see the specification for each Operating Mode in Part B of these Instructions. In the normal case, the exposure time entered may be used to obtain a single image, to obtain a series of spectra (ACCUM spectra with STIS using PATTERN, for example), or to perform a complex, autonomous target acquisition. If the exposure time is greater than the amount of unocculted time available, the exposure may be broken into a group of subexposures by the planning system; this default splitting may be prevented by using the exposure-level Special Requirement NO SPLIT. The amount of viewing time depends on the target’s declination, date of observations, and the HST orbital parameters. Routine calibration exposures will be performed by STScI. If special internal calibrations are required for your program, consult the Internal Calibration Target tables in Part B of these Instructions for information about what exposure times to use. Use the Target Acquisition sections of the Instrument Handbooks and STScI web tools to estimate exposure times used for acquisition exposures. Exposure times may be changed during scheduling by STScI in order to place exposures in observing windows defined by orbital constraints (Earth blockage, passage through the SAA, etc.) and to improve overall efficiency; the exposure-level Special Requirements EXPAND, MAX DUR, and MIN DUR (see Timing Requirements on page 143 for details) can be used to control these changes in exposure time. If no preference is specified by the observer, changes to exposure times will be such that the exposure time is not changed by more than about 20%; note that increases, as well as decreases, in exposure time are possible. 100 Chapter 5: Visits and Exposures Target acquisition and peakup exposure times are not altered during scheduling. Exposure-level Special Requirements [Special_Requirements] A variety of exposure-level Special Requirements may be entered; these requirements apply to individual exposures in a visit (visit-level Special Requirements are discussed in Chapter 7: Special Requirements [Visit_Requirements and Special_Requirements] on page 111). These requirements will be interpreted by the computer software that is used to schedule the observations; therefore it is absolutely essential that the specific formats shown in Chapter 7: Special Requirements [Visit_Requirements and Special_Requirements] on page 111 are followed precisely. If none of the allowed Special Requirements appears to be sufficient, it is permissible to describe the requirements with a text explanation using the “Comments” keyword. You should contact your Program Coordinator prior to entering such a comment in your proposal. Several of these Special Requirements require the use of limited resources or may impose serious constraints on the scheduling system (e.g., RT ANALYSIS, REQ UPLINK). These Special Requirements should be used with care. The exposure-level Special Requirements are described in detail in Chapter 7: Special Requirements [Visit_Requirements and Special_Requirements] on page 111. If more than one Special Requirement is needed for a visit, they should be separated by a space, carriage return, or semi-colon, but not by a comma. Exposure-level Comments [Comments] Information that cannot be made to conform to the required formats may be entered as a comment. Comment lines are not interpreted by the software, but are maintained in the database and do appear on printouts of the programs. Comments should be used sparingly, if at all. They are intended only for the small number of programs whose requirements cannot be met with standard and supported features. CHAPTER 6: Parallel Science Exposures For an explanation of this engineering-only version, see Special Note to Engineering Version Users in Chapter 1: About This Document on page 3. In this chapter . . . Parallel Science Limitations / 102 Pure Parallels / 103 Coordinated Parallels / 105 HST is, of course, a telescope with instruments that have relatively small apertures that must be accurately pointed to achieve useful scientific results. However, the value of “parallel” observations was recognized during the earliest stages of HST’s design because by turning on other instruments one could discover new objects and new phenomena, or just acquire highly detailed images of random regions of the sky that are the equivalent of a survey. This parallel capability was present to a limited degree at launch, but it has become especially important since the second servicing mission because now WFPC2 and STIS can both work at the same time. Even without NICMOS, the parallel capacity of HST is substantial. Parallel science refers to the use of two or more Science Instruments at the same time. The primary observation is the one that has determined the pointing of HST and it always takes precedence. The parallel observation is the one enabled to take place because the primary observation permits suitable conditions, but the parallel observation must never interfere with the primary. Although parallel observations are conceptually simple (e.g., “Turn on WFPC2 with the F555W filter while STIS is in use”), they are, in fact, complex to execute. Commanding the instruments for parallels and primaries at the same time requires strict observance of complex timing 101 102 Chapter 6: Parallel Science Exposures rules in order to avoid damage to instruments. Some special restrictions must be applied in order to effectively schedule and execute parallel observations. From the point of view of the HST ground systems there are two types of parallel exposures: pure and coordinated parallels. • Coordinated parallels are written to be part of the same proposal, with the intention of scheduling the primary and the parallels together. Coordinated parallels are inextricably linked with their primaries: both must be scheduled in order for either to be scheduled. • Pure parallels are scheduled separately from primaries late in the scheduling process (essentially after the primary science schedule has been completely constructed). This type of parallel must be used whenever the primary and parallel exposures come from different proposals. The scheduling of pure parallels has no effect on the primary schedule: pure parallels will be placed on the schedule only when there are suitable opportunities available. The HST pointing control system will automatically correct for differential aberration effects for the PRIMARY observations. There will be a small smearing effect in the parallel SI which cannot be corrected on-board. The magnitude of the effect will vary with the primary target location and aperture, but will be a maximum of +/– 0.020 arcsec. Parallel Science Limitations These restrictions are to ensure that parallels can be scheduled and executed safely and efficiently: • Parallel observations have some special restrictions on the targets that may be specified; see Pure Parallels on page 103 and Coordinated Parallels on page 105 for details. • All scheduling constraints (pointing, orientation, and relative timing) that apply to coordinated primaries and parallels must be specified only on the primary exposure. • No visit-level special requirements, and only a few exposure-level special requirements, are applicable to pure parallel visits. Pure Parallels 103 • Exposures parallel with any instrument mode which permits interactive or autonomous motion of HST (e.g., interactive or onboard acquisitions) are not supported. • Neither parallel exposures nor the primary of a coordinated parallel may have real-time (i.e., TDRS contact) requirements of any kind. • Parallel observations may not be made while STIS MAMA TIME-TAG observations are being made. These limitations are discussed further below. Pure Parallels Pure parallel visits are identified by a Proposal_Category (see Proposal Information [Proposal_Information] on page 12) that ends with /PAR (not the former PARallel visit special requirement). All visits in such proposals will be interpreted as pure parallel visits. Pure parallel proposals require additional information at the proposal level to specify pointing tolerances (see Parallel Information [Parallel_Pointing_Tolerance] on page 14). At the visit level, the Visit_Priority (see Visit Priority [Visit_Priority] on page 91) must be specified to provide guidance for the scheduling system. Parallel visits using the same target will be considered in order of Visit_Priority. A range of visits designed for opportunities of different lengths (say 1 to 10 orbits) is recommended, with the longer visits being given higher priority. At each opportunity on the calendar which matches the pointing of a set of parallel visits and whose pointing is stable within the proposal’s Parallel_Pointing_Tolerance, STScI will schedule the highest-priority visit that fits in the opportunity. Exposures within a visit will be obtained consecutively and in the order specified, just as with primary visits. How Pure Parallels Are Scheduled Observer-defined visits correspond to scheduling units (SUs) in the HST ground system. An SU is a set of exposures which must be scheduled at the same time. An SU with coordinated parallel exposures is scheduled just like one without parallels. However, pure parallel SUs are scheduled through a separate process. First the scheduling system builds a calendar from primary visits. Once the primary calendar is complete, a description of it is used to find appropriate parallel SUs to match the opportunities from the primary calendar. These parallels are then scheduled, subject to the constraints of the primary SUs already on the calendar. 104 Chapter 6: Parallel Science Exposures While a primary visit is only scheduled once, a parallel visit may be scheduled many times (and generating a new SU each time) whenever it is the most appropriate use of an opportunity on the calendar. On the other hand, if a parallel visit never turns out to be the most appropriate, it will never be scheduled at all. Instrument Configuration Pure parallel exposures are limited to the following instrument configurations and modes: Configuration Operating Mode WFPC2 IMAGE STIS/CCD ACCUM Restricted Configuration Operating Mode NIC1 or NIC2 or NIC3 ACCUM, MULTIACCUM Every exposure in a pure parallel proposal must use the same instrument. For NICMOS, coordinated parallels using different detectors are not allowed in pure parallel visits. Special Requirements No visit-level special requirements are allowed in pure-parallel visits. Exposure-level special requirements are limited to the following: END ORBIT; EXPAND; MAXimum DURation; MINimum DURation; NO-SPLIT; PARallel <parallel-exp-list> WITH <primary-exp-list>1 (Restricted) SEQuence <exposure-list> NON-INTerruptible We recommend that MINimum DURation, plus either MAXimum DURation or EXPAND, be specified on all pure-parallel exposures, except with NICMOS, where no adjustment of exposure time is possible. If MIN DUR is omitted, the default minimum exposure time is set to 80% of Time_Per_Exposure. If MAX DUR is omitted, the default maximum 1. Coordinated parallel exposures are allowed in pure-parallel visits only to support observing with different NICMOS detectors, not different SIs. Coordinated Parallels 105 exposure time is unlimited if EXPAND is specified, and is otherwise set to 120% of Time_Per_Exposure. For visits intended to span multiple orbits, END ORBIT should be specified on the exposure that is intended to end each orbit in order to provide STScI with better guidance in matching parallel visits to the sizes of opportunities. Optional Parameters Dithering parameters and wavelength scans with the WFPC2 linear ramp filter are not permitted with pure parallels because the pointing is determined by the primary observation. Coordinated Parallels Coordinated parallel exposures are indicated by the exposure-level special requirement: PARallel <parallel-exp-list> WITH <primary-exp-list> This designates a set of one or more parallel exposures which will execute in parallel with a set of one or more primary exposures in the same visit. Parallel exposures using the same SI or NICMOS detector will be executed in the order specified on the Visit/Exposure Logsheet. The first parallel exposure which uses a given instrument or NICMOS detector will be executed as early as possible, but not before the first primary exposure. The PARallel WITH special requirement must appear on the first exposure in the <primary-exp-list>. Exposures in the <parallel-exp-list> must appear on the Visit/Exposure Logsheet immediately after the exposures in <primary-exp-list>. Parallel exposure numbers should follow this sequence as well. Instrument Configuration The exposures in <primary-exp-list> and <parallel-exp-list> are limited to the following instrument configurations and modes: Configuration Operating Mode WFPC2 IMAGE STIS/FUV-MAMAa ACCUM STIS/NUV-MAMAa ACCUM 106 Chapter 6: Parallel Science Exposures Configuration Operating Mode STIS/CCD ACCUM FGS POS ACS/WFCb ACCUM ACS/HRCb ACCUM ACS/SBCbc ACCUM a. In order to protect the STIS MAMA detectors from inadvertent overillumination, they may be used as coordinated parallels only if an exact spacecraft orientation (ORIENTation) is specified, the coordinates of the parallel field are determined, and the parallel target or field passes the same bright-object screening applied to MAMA primary observations. b. ACS exposures cannot be used in both the <primary-exp-list> and the <parallel-exp-list>, and all ACS exposures in the <parallel-exp-list> must use the same configuration. c. In order to protect the ACS SBC detector from inadvertent overillumination, the ACS/SBC configuration may be used for coordinated parallels only if an exact spacecraft orientation (see ORIENTation <angle1> TO <angle2>) is specified, the coordinates of the parallel field are determined, and the parallel target or field passes the same bright-object screening applied to SBC primary observations. Limited-Access Configuration Operating Mode NIC1 or NIC2 or NIC3 (Restricted) ACCUM, MULTIACCUM All exposures in <primary-exp-list> must have the same Instrument Configuration (Config) and the same Aperture or Field of View (Aperture). Except for the NICMOS, No exposure in <parallel-exp-list> may use the same SI as the primary exposures. NICMOS parallel exposures may use the same SI but only in a different configuration. Targets Coordinated parallels may specify fixed, generic, or solar system targets; the special target ANY; or internal targets. However, the pointing of HST will be determined only by the primary exposures. Any pointing conditions to be applied on the primary+parallel combination must be specified on the primary exposures via exposure-level special requirements, or on the visit as a whole via visit-level special requirements. All external exposures in a given <primary-exp-list> must have the same pointing (this generally means the same target, aperture, and POS TARG). except for NICMOS background patterns (see the discussion of optional parameters below). Coordinated Parallels 107 If a parallel exposure specifies a fixed target, it should be a different target from the primary ones and should appear in the Target List. In this case, an ORIENTation special requirement is required to ensure that the parallel target is in the aperture. It is the observer’s responsibility to verify that the specified orientation will place the parallel target in the aperture; STScI will not check the geometry. Contact your Program Coordinator if you need assistance. If the parallel target is diffuse and the orientation does not matter, a generic target specification should be used. If there is no parallel target as such, and the intent is just to sample whatever the parallel aperture happens to fall on, the ANY target (which should not appear in the Target List) should be used. Generic targets or target ANY should only be used in one of these three cases: 1. The exposure is PARALLEL WITH or SAME POS AS another exposure (so that the pointing is determined by the other exposure), or 2. The visit is a pure parallel (in which case the target will be matched against already-scheduled observations), or 3. The visit is ON HOLD (as with Targets of Opportunity, for example). In this case the target should be replaced by a fixed target when the ON HOLD is removed. Coordinated parallels and their primaries may not use the WFPC2 UVFLAT or VISFLAT internal targets. Special Requirements All the fields on the Visit/Exposure Logsheet should be filled out as for primary exposures. However, the following exposure-level special requirements are disallowed for both primary exposures (any exposure in a <primary-exp-list>) and parallel exposures: EXPAND MAXimum DURation [<time or percentage>] MINimum DURation [<time or percentage>] RT ANALYSIS 108 Chapter 6: Parallel Science Exposures The following exposure-level special requirements are allowed for primary exposures, but not for parallels: END ORBIT LOW-SKY PHASE <number1> TO <number2> POSition TARget <x-value>, <y-value> REQuires EPHEMeris CORRection <id> REQuires UPLINK SAME POSition AS <exposure> SAVE OFFSET <id> SHADOW USE OFFSET <id> AFTER BY <time1> [TO <time2>] (Available but Unsupported) FORMAT [AN or FN or HN] (Available but Unsupported) The following exposure-level special requirements are allowed without restriction: NO SPLIT SEQuence <exposure-list> NON-INTerruptible SAA CONTOUR (WFPC2 only) SAA CONTOUR (Restricted for other than WFPC2) SPECial COMmanding (Restricted) No parallel exposure may appear in the <exposure-list> of an RT ANALYSIS FOR Special Requirement, or be the <exposure> referenced by a SAME POSition AS special requirement. Coordinated Parallels 109 Optional Parameters The WFPC2 READ=NO option is not allowed, because the WFPC2 CCDs are erased during delays between exposures to avoid cosmic-ray effects. The parameters used with patterns for NICMOS may be used for coordinated parallels subject to the following restrictions and interpretations: 1. Only a single NICMOS exposure in the PARallel WITH Special Requirement may use a pattern. This exposure must be the only exposure in <primary-exp-list>. Background pattern parameters may not be used on a parallel exposure, because they involve pointing changes. 2. All NICMOS parallel exposures will be taken at each pattern position. Any parallel exposures using other SIs will also be taken at each pattern position. 3. Only a single NICMOS exposure in the PARallel WITH special requirement may use a pattern, and no other exposure in the list may use the same configuration. This exposure must be either the only exposure in <primary-exp-list> or the first exposure in <parallel-exp-list>. 4. Background pattern parameters may be used on a parallel exposure only if OFFSET=FOM and the primary exposures use an SI other than NICMOS. 5. All other NICMOS parallel exposures will be taken at each pattern position. If the exposure using the background patterns is the primary, parallel exposures using other SIs will also be taken at each pattern position. 6. If OFFSET=FOM, each sequence of NICMOS exposures in <parallel-exp-list> using a different detector must take no longer to execute than the exposure with OFFSET=FOM. Within a PARallel WITH special requirement, the NICMOS CAMERA-FOCUS, optional parameter may be used only by one NICMOS detector, referred to as the “primary detector.” If the primary exposures use the NICMOS, the primary detector is the one used in those exposures. Otherwise, the primary detector is determined by the configuration used for the first NICMOS exposure in <parallel-exp-list>. Within a PARallel WITH special requirement, the NICMOS FOMXPOS, FOMYPOS, and LAMP (Restricted) optional parameters may be used only by one NICMOS detector, referred to as the “primary detector.” If the primary exposures use the NICMOS, the primary detector is the one used in those exposures. Otherwise, the primary detector is determined by the configuration used for the first NICMOS exposure in <parallel-exp-list>. 110 Chapter 6: Parallel Science Exposures Ordering Restrictions and Interpretations The exposures in the <parallel-exp-list> of a PARallel WITH special requirement must appear on the Visit/Exposure Logsheet immediately after the exposures in <primary-exp-list>. If the <parallel-exp-list> contains exposures which use different SIs or NICMOS detectors, an attempt will be made to execute each group of exposures with the same SI or NICMOS detector in parallel with the other groups. All exposures within a given group must be contiguous on the logsheet.Groups of parallel exposures using different NICMOS detectors must be contiguous on the logsheet. Within a group, exposures will be executed in the order in which they appear on the logsheet. Due to readout conflicts and limits on the number of SIs which may execute simultaneously, parallel exposures sometimes have to be delayed. If a parallel exposure conflicts with an exposure in its <primary-exp-list>, the parallel will be delayed. If two parallel exposures using different SIs or NICMOS detectors conflict, the exposure which appears later on the logsheet will be delayed. Following a set of exposures in <primary-exp-list> and <parallel-exp-list>, subsequent exposures not part of either list will be delayed until after all primary and parallel exposures have completed. Example 1: Three WFPC2 exposures parallel with three STIS exposures 1 2 3 4 5 6 STISPAR 4-6 WITH 1-3 STIS STIS WFPC2 WFPC2 WFPC2 Efficiency Considerations Within a set of coordinated-parallel exposures, the ground system will not break up sequences of exposures that are too long to fit in an orbit, as it does for non-coordinated-parallel exposures. Each group of exposures with the same SI or NICMOS detector must be short enough to fit in one orbit. If it is necessary to take coordinated-parallel data over multiple orbits, a separate PARallel WITH special requirement – with a new <primary-exp-list> and <parallel-exp-list> – should be specified for each orbit. CHAPTER 7: Special Requirements [Visit_Requirements and Special_Requirements] For an explanation of this engineering-only version, see Special Note to Engineering Version Users in Chapter 1: About This Document on page 3. In this chapter . . . Introduction to Special Requirements: Syntax and Rules / 112 Visit-level Special Requirements / 117 Guiding / 117 Target Orientation / 119 Special Observation Requirements / 129 Timing Requirements / 131 Conditional Requirements / 134 Exposure-level Special Requirements / 134 Target Acquisition / 134 Target Position / 137 Special Observation Requirements / 139 Special Communications Requirements / 141 Timing Requirements / 143 Implementation Special Requirements (Engineering) / 147 111 112 Chapter 7: Special Requirements [Visit_Requirements and Tables and Figures Hint: To go directly to information for a particular Special Requirement, go to the tables that follow below, and click on any entry in blue. Table 7.1: Supported Formats for Visit Level Special Requirements Table 7.1: Limited-Access Formats for Visit Level Requirements Table 7.2: Supported Formats for Exposure Level Special Requirements Table 7.2: Limited-Access Formats for Exposure Level Requirements Table 7.2: Formats for Implementation Special Requirements Table 7.3: Accuracies of Guiding Modes Table 7.3: Accuracies of Guiding Modes (Restricted) Figure 7.1 ORIENTation computation for WFPC2 Figure 7.2 ORIENTation computation for STIS. Figure 7.3 ORIENTation computation for FGS1R, in TRANS mode. Table 7.4: Instrument Orientations with respect to U3-Direction Table 7.4: Limited-Access Orientations with respect to U3-Direction Table 7.5: Approximate Separation and Orientations between Instrument Detectors Table 7.5: Approximate Separation and Orientations between Restricted Instrument Detectors Introduction to Special Requirements: Syntax and Rules Special requirements provide flexibility in specifying the scheduling requirements of observations. Many Special Requirements, directly or indirectly, restrict the times when observations can be scheduled. These should be used to provide the schedulers at STScI with enough constraints to ensure that the observations are properly scheduled. Special Requirements should not be used unless necessary to accomplish the scientific objectives of the program. The Special Requirements are summarized in Table 7.1: Supported Formats for Visit Level Special Requirements and Table 7.2: Supported Introduction to Special Requirements: Syntax and Rules 113 Formats for Exposure Level Special Requirements, and a detailed description of each requirement is provided in the following subsections. The following conventions and rules should be observed when reading the descriptions of the Special Requirements and when entering them. • It is permissible to use only the portions of the keywords that are shown in upper-case letters in Table 7.1 and Table 7.2 and in the discussion below. The portions in lower-case letters are included for clarity only. For example, SEQ could be entered rather than SEQUENTIAL. • Items inside angular brackets (< >) in the Special Requirement descriptions are to be replaced with the relevant information. All indicated items must be provided, except for items inside square brackets ([ ]), which are optional. For example, the general specification SEQuential <visit-list> [WITHIN <time>] means that SEQ 5–7 WITHIN 10D and SEQ 5–7 are acceptable, but SEQ WITHIN 10D is not. • Exposures must be referred to by their exposure numbers. <exposure> must be replaced by the number of a single exposure. <exposure-list> must be replaced by one of the following: A single exposure number; several exposure numbers separated by commas or spaces; or a range of exposure numbers separated by a hyphen. The following are all valid examples for SEQuence <exposure-list> NON-INTerruptible: SEQ 2-5 NON-INT, SEQ 4, 5, 11 NON-INT, SEQ 6-7 14-15 NON-INT. Hyphens may be used in exposure lists to indicate a range (e.g., SEQ 15–17 NON-INT). • A <date> specification in a Special Requirement must either be a geocentric date expressed in Universal Time (UT) or a heliocentric Julian Date. A UT date must be entered in the form DD-MMM-YYYY:hh:mm:ss.s, where MMM represents the first three letters of the month name. For example, 14-DEC-2001:17:05:41.1 refers to 14 December 2001, geocentric UT 17H05M41.1S. Only the necessary precision need be employed (e.g., 14-DEC-2001 might be adequate), but four-digit years are now mandatory. Julian Dates must be entered in the form JDnnnnnnn.nnn (e.g., JD2444123.4). Only the required precision need be provided. All Julian Dates will be interpreted as heliocentric. • All <time> specifications must be expressed in one of the following: days (D), orbits (ORBITS), hours (H), minutes (M), or seconds (S). All other time units (such as weeks, months or years), as well as combined time units (such as 14D 15H), are not permitted. 114 Chapter 7: Special Requirements [Visit_Requirements and Note that users may also specify a date in the day-of-year format, such as 2000.189. Such a date must use a 4-digit year and a 3-digit integer for the day (fractions of days are not allowed). This capability is advertised only in the Engineering version of these Instructions to reduce confusion for GOs, but the software does not restrict the usage, so be careful. • Multiple Special Requirements entered on the same line may be separated by a semi-colon (;) for the sake of readability, but this is now optional. Multiple Special Requirements separated by different lines need no further delimiting. Under no circumstances should a comma be used to separate Special Requirements. • A visit-level Special Requirement (Visit_Requirements) applies to ALL the exposures within that visit. • An exposure-level Special Requirement (Special_Requirements) applies ONLY to that exposure and any other referenced exposures within the same visit. For example, SEQ 4–6 NON-INT on exposure 1 means that exposures 4-6 MUST be in the same visit as the exposure 1. Table 7.1: Supported Formats for Visit Level Special Requirements FORMAT EXAMPLE Guiding Requirements PCS MODE Fine PCS MODE F PCS MODE Gyro PCS MODE G GUIDing TOLerance <angle> GUID TOL 0.020" DROP TO GYRO IF NECESSARY [NO REACQuisition] DROP TO GYRO IF NECESSARY Target Orientation Requirements ORIENTation <angle1> TO <angle2> ORIENT 18D TO 22D ORIENTation <angle1> TO <angle2> FROM <visit> ORIENT 18D TO 22D FROM 5 SAME ORIENTation AS <visit> SAME ORIENT AS 5 Special Observation Requirements CVZ CVZ SCHEDulability <percentage> SCHED 50% Introduction to Special Requirements: Syntax and Rules FORMAT 115 EXAMPLE Timing Requirements AFTER <date> AFTER 12-JUL-2001:12:06 AFTER <visit> [BY <time1> [TO <time2>]] AFTER 6 BY 7D TO 9D BEFORE <date> BEFORE 14-SEP-1999 BETWEEN <date1> AND <date2> BETWEEN 21-DEC-1999 AND 31-DEC-1999 GROUP <visit-list> WITHIN <time> GROUP 5-10 WITHIN 60D PERIOD <time> AND ZERO-PHASE <date> PERIOD 1.23H AND ZERO-PHASE JD2444000 SEQuence <visit-list> WITHIN <time> SEQ 5-7 WITHIN 24H Conditional Requirements ON HOLD [FOR <visit-list>] ON HOLD FOR 15 Table 7.1 (cont): Limited-Access Formats for Visit Level Requirements FORMAT EXAMPLE Special Observation Requirements PARallel (Available but Unsupported) PAR CAMPAIGN (Available-but-Unsupported) STIS-LOW-BACKGROUND CAMPAIGN STIS-LOW-BACKGROUND Table 7.2: Supported Formats for Exposure Level Special Requirements FORMAT EXAMPLE Target Acquisition Requirements INTeractive ACQuisition (obsolete) No longer available; see text. Target Position Requirements POSition TARGet <X-value>, <Y-value> POS TARG +6.3,-8.1 SAME POSition AS <exposure> SAME POS AS 6 PATTERN see Chapter 8: Pointings and Patterns on page 153 Special Observation Requirements PARallel <parallel-exp-list> WITH <primary-exp-list> PAR 4-6 WITH 1-3 SAA CONTOUR <model number>: (WFPC2 only) SAA CONTOUR 02 Special Communications Requirements RT ANALYSIS RT ANALYSIS REQuires UPLINK REQ UPLINK REQuires EPHEMeris CORRection <id> REQ EPHEM CORR OFF-13 Timing Requirements END ORBIT END ORBIT EXPAND EXPAND 116 Chapter 7: Special Requirements [Visit_Requirements and FORMAT EXAMPLE LOW-SKY LOW-SKY MAXimum DURation [<time or percentage>] MAX DUR 115% MINimum DURation [<time or percentage>] MIN DUR 30M NO SPLIT NO SPLIT PHASE <number1> TO <number2> PHASE 0.09 TO 0.11 SEQuence <exposure-list> NON-INTerruptible SEQ 2-5 NON-INT SHADOW SHADOW VISIBILITY INTERVAL NIC-CORON VISIBILITY INTERVAL NIC-CORON Table 7.2 (cont): Limited-Access Formats for Exposure Level Requirements FORMAT EXAMPLE Target Acquisition Requirements SAVE OFFSET <id> (Available but Unsupported) SAVE OFFSET OFF-1 USE OFFSET <id> (Available but Unsupported) USE OFFSET OFF-1 Special Observation Requirements SAA CONTOUR <model number>: (Restricted) SAA CONTOUR 02 SPECial COMmanding [INSTR <name>] (Restricted) SPEC COM INSTR ESPFORMAT Special Communications Requirements FORMAT [AN or FN or HN or PN] (Available but Unsupported) FORMAT FN Timing Requirements AFTER BY <time> [TO <time2>] (Available but Unsupported) AFTER BY 15M to 16M Table 7.2 (cont): Formats for Implementation Special Requirements FORMAT EXAMPLE Visit Special Requirements VISIBILITY INTERVAL NIC-CORON VISIBILITY INTERVAL 5000 S Exposure Special Requirements NEW OBSET [FULL ACQ] NEW OBSET NEW ALIGNMENT NEW ALIGNMENT SAME OBSET <exposure-list> SAME OBSET 10-20 SAME ALIGNMENT <exposure-list> [DONT SPLIT] SAME ALIGNMENT 20-30 SAME GUIDE STARS <exposure-list> SAME GUIDE STARS 10-20 GSPAIR <pair-id-> GSPAIR 0748300182F10000000000F0 OBSET ID <id> OBSET ID A2 EXP PCS MODE [FINE | GYRO] EXP PCS MODE FINE GS ACQ SCENARIO [PAIR | SINGLE | GYRO | <scenario>] GS ACQ SCENARIO SINGLE Visit-level Special Requirements 117 Visit-level Special Requirements The following Special Requirements are applicable at the visit level, and they will affect all the exposures within that particular visit. Guiding There are currently two tracking modes available during HST observations. One of the modes employs guide stars and the Fine Guidance Sensors: Fine Lock. Alternatively, observations can be made while the HST is stabilized with gyros. (In this scenario no guide star acquisition occurs, and the absolute error of positioning is 14 arcsec with a drift rate of about 0.0014 arcsec/sec.) The typical guiding accuracies for the two modes are listed in Table 7.3 Table 7.3: Accuracies of Guiding Modes Guiding Mode Guiding Accuracya Gyro hold Fine lock Drift rate 0.0014 arcsec/sec RMS jitter 0.005 arcsec a. Excluding periods during day/night terminator crossings, where jitter can be as high as 0.035 arcsec rms over a period of 5 minutes. Table 7.3 (cont): Accuracies of Guiding Modes (Restricted) Guiding Mode Guiding Accuracya Coarse track RMS jitter 0.015 arcsec a. Excluding periods during day/night terminator crossings, where jitter can be as high as 0.035 arcsec rms over a period of 5 minutes. All observations will be performed using Fine Lock guiding by default whenever possible. If difficulties are encountered finding guide stars, you will be contacted by STScI. It has been determined that using Coarse Track guiding for long periods of time is hazardous to the health of the Fine Guidance Sensors, so use of this tracking mode will be considered for extreme cases only. If you cannot find what you feel to be an appropriate tracking mode, you are urged to contact your Program Coordinator for help resolving the issue. PCS MODE Fine Specifies the use of Fine Lock as the guiding mode for the exposures defined in that particular visit. This Special Requirement is the default and any use of the GUIDing TOLerance <angle> overrides this Special Requirement. 118 Chapter 7: Special Requirements [Visit_Requirements and PCS MODE Gyro Specifies the use of Gyro hold as the guiding mode for the exposures defined in that particular visit. This mode is available ONLY with the WFPC2, ACS/WFC, ACS/HRC, NICMOS, S/C and STIS/CCD SI/detector combinations. It is prohibited with other SIs because of concern that gyro drift will result in inadvertent exposure to bright objects. Note that the RMS absolute pointing error for gyro hold is 14 arcsec with a drift rate of about 0.0014 arcsec/sec. This Special Requirement overrides the default and any use of the GUIDing TOLerance <angle> Special Requirement. GUIDing TOLerance <angle> GUID TOL <angle> specifies a non-default guiding tolerance for the exposures contained within that particular visit. The <angle> is the allowed maximum pointing error for the observations; the units must be given (" is typical, but arcmin or degrees are acceptable). The GUIDing TOLerance should be used in situations when it is permissible for a portion of the observation to be taken while guiding on gyros. The GUID TOL Special Requirement is also used as a trigger for the guide star handoff capability. This capability is useful for fast moving targets, as well as multi-orbit observations of all moving targets. The handoff process involves using a single pair of guide stars for as long as possible. When a given exposure cannot be completed with a given pair of guide stars, guidance is transferred to gyro control. The fine guidance sensors are slewed to and acquire a new pair of guide stars before the exposure in question begins. The error in this procedure is due to the accumulated drift during gyro control, typically a few tenths of an arcsec at most. Note that this is much less than the nominal error between guide star pairs. The planning system will schedule the observations so that the expected pointing-error buildup remains below the <angle> specified. Guide star handoff will only be used if a single pair of guide stars cannot be found for the observation. If you need to use the guide star handoff capability, then set GUID TOL to at least 0.11". Note that the difficulty in finding guide stars for these types of observations may prevent them from being scheduled. If you plan to use this Special Requirement, please contact your Program Coordinator for further details and discussions. DROP TO GYRO IF NECESSARY [NO REACQuisition] This Special Requirement allows the system to drop guide-star control for exposures with pointings (target/aperture positions) that are too far (more than 2 arcmin) from the first pointing in the visit to use the same guide stars. If this Special Requirement is not used, such exposures will Visit-level Special Requirements 119 have to be taken using a separate pair of guide stars. The NO REACQ qualifier will disable guide-star reacquisition after dropping to gyro control, even if subsequent pointings are close enough to the first pointing in the visit to allow guide-star control to be resumed. This Special Requirement has no meaning for internal observations and visits with PCS MODE Gyro. This Special Requirement is allowed ONLY with the WFPC2, NICMOS,ACS/WFC, ACS/HRC, and STIS/CCD SI/detector combinations (see the above discussion of PCS MODE Gyro). DROP TO GYRO is not allowed with the ACS/SBC configuration because of concern about bright objects. See the discussion of the GUIDing TOLerance <angle> Special Requirement concerning the pointing drift that will occur while the spacecraft is under gyro control. Due to this drift, this requirement is useful primarily for short observations (bright targets) where pointing is not critical (e.g. imaging). This capability might be used if, after spending most of an orbit obtaining spectra of a target, you want to get a quick image without having to acquire a new set of guide stars. Some uses of the WFPC-2 linear ramp filters might be more efficient if this requirement is used. Target Orientation The solar arrays of HST must be kept pointed at the Sun (to within a modest angle) in order for the spacecraft to have the electrical power it needs. As the Sun moves through the heavens over the course of a year, this requirement for the solar arrays translates into a position angle on the sky on which HST’s detectors lie. Therefore an observer-imposed requirement to, say, orient a slit in a particular position angle means that observation must be done at a specific time. When a special aperture orientation is requested, this will generally be accommodated by scheduling the observation during the time interval when that orientation naturally results in the solar array being positioned nearly perpendicular to the Sun (this is called the “nominal” orientation). In order to achieve a specific orientation and satisfy spacecraft roll constraints, an observation generally must be scheduled within a fairly narrow time interval. The placement and duration of time intervals that satisfy this constraint will depend on the ecliptic coordinates of the target. The observer must take this into consideration when specifying additional timing constraints (e.g. BETWEEN, BEFORE, AFTER). For a discussion of nominal roll and how it changes with time based on ecliptic latitude, see ORIENTation <angle1> TO <angle2> FROM <visit> below. 120 Chapter 7: Special Requirements [Visit_Requirements and Observers should specify orientations by specifying the position angle of the orientation reference vector U3, as listed in Table 7.4: Instrument Orientations with respect to U3-Direction. To avoid confusion with the spacecraft V2, V3 axes, we define U2, U3 axes which lie in the HST focal plane as projected onto the sky. The U2- and U3-directions are defined by the “nominal” Optical Telescope Assembly (OTA) axis, which is near the center of the WFPC2 CCDs, and the nominal centers of the projected FGS1R, FGS3 and FGS2R FOVs, respectively. To specify a special orientation of an aperture, slit, aperture pair, etc., the observer should algebraically add two angles: • The position angle on the sky of the feature to be aligned. • The “offset angle,” which is the angle from an aperture axis to the +U3 axis. This aperture axis may be the X or Y axis of an SI, or one of the aperture-related features given in Table 7.4. The “offset angle” could also be the angle of the line separating two instruments (Table 7.5) if that is the relevant orientation. The axes for the SIs are given in the SI-specific chapters in Part B. The algebraic sum of the aperture orientation and the offset angle is the U3 orientation, which should be specified in the ORIENTation <angle1> TO <angle2> and ORIENTation <angle1> TO <angle2> FROM <visit> Special Requirements described below. All angles are measured North through East, or counterclockwise when referring to the figures in this section. If there is any uncertainty in specifying an orientation, please document the calculations in the Visit_Comments and contact your Program Coordinator for clarification. If a visit contains multiple targets requiring different guide stars, the spacecraft orientation will normally be reset to the “nominal” orientation each time a new set of guide stars is acquired. However, if the visit has an ORIENTation <angle1> TO <angle2> FROM <visit>, SAME ORIENTation AS <visit>, or ORIENTation <angle1> TO <angle2> FROM <visit> Special Requirement, the spacecraft orientation will not change during the visit, even if multiple sets of guide stars are needed. Examples of Orientation Angle Computations We show three examples of how to compute an orientation angle, one for each of the three Cycle 10 instruments. ORIENTation <angle1> TO <angle2> Specifies that a specific absolute roll angle or orientation of the spacecraft is required for the exposures within the current visit. <angle1> and Visit-level Special Requirements 121 <angle2> denote a region within which the position of the U3 axis on the sky (measured North through East) must fall at the time of the observation; both limits must be between 0 (0D) and 360 degrees (360D). If necessary, it is possible for <angle1> and <angle2> to be equal, but the size of the region between the two limits should be made as large as possible to make scheduling easier. Note that in most instances the angles can have a 180 degree offset and still work. If this is desired (for greater scheduling flexibility), please specify the additional possible angles. Figure 7.1: ORIENTation computation for WFPC2 N 120D PC E 45D U3 +x jet WF4 255D In this example we wish to observe an object with a jet that lies at PA 120 degrees. There is some additional structure to the north of this jet, so we have chosen to center the object in the PC chip (for the best spatial resolution) with the jet to lie across the WF4 chip. As shown in Table 7.4, for WFPC2 the +X axis is 45D away from the U3 axis. Therefore the nominal orientation is 120D (the angle from north to the jet) + 90D (from the jet to the +X axis) + 45D (from the +X axis to U3), or 255D. The nature of the object leads us to estimate that this angle can differ from nominal by up to 10 degrees, and therefore we specify: ORENT 245D TO 265D Note also that this Special Requirement can now list several acceptable angle ranges: ORIENTation <angle1> TO <angle2> 122 Chapter 7: Special Requirements [Visit_Requirements and ORIENTation <angle3> TO <angle4> ORIENTation <angle5> TO <angle6> ORIENTation <angle7> TO <angle8> . . . Both angles are measured in a counterclockwise direction, so if the orientation region crosses zero (celestial North), <angle1> would be greater than <angle2>. Otherwise, <angle1> should be less than <angle2>. It is also possible for the orientation region to be larger than 180 degrees. You are encouraged to enter both the aperture angle(s) and the offset angle used to calculate these angles in the Visit_Comments. Note: If the visit uses multiple targets, the direction of North from the first target will be used. The spacecraft will not roll between targets, so that the U3 position angle at the new target may be slightly different from that of the first target. It is sometimes desirable for a new observation to be taken at the same orientation as an existing archival image, using the “PA_V3” field from the header in the archive. For the WFPC2, it is necessary to add or subtract 180 degrees from the “PA_V3” angle before using it in the ORIENTation Special Requirement. ORIENTation Special Requirements are a limited resource and should be used only when necessary. Visit-level Special Requirements 123 Figure 7.2: ORIENTation computation for STIS. N U3 15D +y 60D E In this example we consider a close binary system in which the position angle of the line joining the stars is 60D. We wish to position the slit to exclude light from the companion star, so that the +Y axis (the long direction of the slit) is at –30 degrees. The U3 axis (Table 7.4) lies at 45 degrees from +Y, or at PA 15D. If a tolerance of 12D is allowed, we would then specify ORIENT 3D TO 27D. Because of the symmetry of the slit, it would also work if the orientation were flipped 180 degrees, so the net specification is: ORIENT 3D to 27D ORIENT 183D TO 207D ORIENTation <angle1> TO <angle2> FROM <visit> Specifies that a roll angle or orientation of the spacecraft, relative to another visit’s spacecraft orientation, is required for the exposures within the current visit. <angle1> and <angle2> denote a region of permitted orientation of the current visit relative to <visit>. <angle1> and <angle2> must be between –180 degrees (–180D) and +180 degrees (180D). If necessary, it is possible for <angle1> and <angle2> to be equal, but the size of the region between the two limits should be made as large as possible to make scheduling easier. Both angles are measured in a counterclockwise direction, so if the orientation region crosses a point 180 degrees from <visit>, <angle1> should be positive and <angle2> negative. Otherwise, <angle1> should be less than <angle2>. It is possible for the orientation region to be larger than 180 degrees. 124 Chapter 7: Special Requirements [Visit_Requirements and Figure 7.3: ORIENTation computation for FGS1R, in TRANS mode. N +x 15D 45D E +y 195D U3 In this example we consider the same close binary system in which the position angle of the line joining the stars is 60D. The scans will be done parallel to the line joining the binary components, with a tolerance of 20 degrees. TRANS mode scans move the instantaneous field of view at an angle of 45 degrees relative to the FGS1 axes. The +X axis will have a PA of 60 degrees, minus the 45 degree offset, or 15D. The U3 axis is 180 degrees from +X (Table 7.4), thus we specify: ORIENT 175D TO 215D Orientation constraints translate into timing constraints. Generally, if the spacecraft is unable to roll far enough off-nominal to satisfy the required difference in orientation between the two visits, they will be forced apart in time in order to schedule both at near nominal roll. “Nominal roll” is the orientation determined by the necessity of keeping the solar panels perpendicular to the Sun. Targets near the ecliptic have two values of nominal roll through the year 180 degrees apart. Near the ecliptic pole, nominal roll varies by about a degree per day. In general, the off-nominal roll is limited to less than +/– 30 degrees except when the target is within two degrees of opposition (i.e., exactly opposite the Sun in the sky as viewed from the Earth). Observations scheduled with solar elongations between 90 degrees and 178 degrees can be done at up to 23 to 30 degrees off nominal, depending on the exact elongation. For observations scheduled when the target is within 90 degrees of the Sun, the Visit-level Special Requirements 125 off-nominal roll is limited to 5 degrees. The legal syntax for <angle1> and <angle2> allows angles between –180 degrees (–180D) and +180 degrees (180D). Please contact your Program Coordinator for details if necessary. This Special Requirement is a limited resource and should be used only when necessary. To specify that the current visit be scheduled at the same orientation as another visit, use the SAME ORIENTation AS <visit> Special Requirement. 126 Chapter 7: Special Requirements [Visit_Requirements and Table 7.4: Instrument Orientations with respect to U3-Direction Instrument Item Offset Anglea FGS (Figure 11.1: The FGS POS TARG and interferometer coordinate systems.) +X axis for FGS1 180° +X axis for FGS2 90° +X axis for FGS3 0° STIS (see STIS Instrument Handbook)) All configurations: Comments Nominal, +/– 4D Long Slit Spatial/+AXIS2/+Y 45D Dispersion/+AXIS1/+X 135D Toward increasing occultation: WFPC2 (Figure 9.1: WFPC2 Aperture Coordinate System) WEDGEA 45D WEDGEB 135D WFC +X axis 45D WF2 bloom direction 45D, 225D WF3 bloom direction 135D, 315D WF4 bloom direction 45D, 225D PC1 +X axis 45D PC1 bloom direction 135D, 315D Linear Ramp Filters, Nominal 135D, 315D Polarizers Coincident with CCD Relative polarization angles POL0-WF2 45D POL45-WF3 0D POL90-WF4 315D POL135-PC1 270D POL-33-WF2/WF3 303D a. The Offset Angle is the angle from the axis defined in the Item column to the +U3 axis in the counterclockwise (or +U3 through +U2) direction. To compute the angle needed in the ORIENT Special Requirement, add this Offset Angle in column 3 to the Sky Position Angle (measured North through East). These angles are calculated from current alignment calibrations and reflect uncertainties of +/– 3 degrees, except where greater uncertainties are indicated in the table comments. Visit-level Special Requirements 127 Table 7.4 (cont): Limited-Access Orientations with respect to U3-Direction Instrument Item Offset Angle Comments NICMOS (Restricted) (Figure 13.1: NICMOS Coordinate System., Figure 13.2: Definition of Orientation for NICMOS.) NIC1 +Y axis 225D Nominal, +/– 4D NIC2 +Y axis 225D NIC3 +Y axis 225D Line joining NIC3 and NIC1 225D Line joining NIC3 and NIC2 225D NIC3 Grism Dispersion (toward increasing wavelength) 135D STIS WFPC2 (Figure 9.1: WFPC2 Aperture Coordinate System) Planetary slits spatial: P45 N45 90D 0D LRF, Rotated 33D 168D, 348D (From nominal) LRF, Rotated 18D 152D, 333D (From nominal) WARNING: For any detailed orientation requirements, please describe your requirements clearly in the proposal text and give angles and offsets. Please feel free to contact your Program Coordinator for assistance in preparing your orientations. Table 7.5: Approximate Separation and Orientations between Instrument Detectors Instrument Aperturesa Separationb (arcsec) Offset Anglec (degrees) FGS WFALL-FIX to FGS1 721 +/3 88.6D WFALL-FIX to FGS2 737 +/3 89.8D WFALL-FIX to FGS3 728 +/3 270.1D WFALL–FIX to STIS 318d 317D STIS 128 Chapter 7: Special Requirements [Visit_Requirements and Instrument Aperturesa Separationb (arcsec) Offset Anglec (degrees) WFPC2 WFALL-FIX to WF4-FIX 55 +/- 1 75D +/- 0.3D WFALL-FIX to WF3-FIX 39 +/- 1 180D +/- 0.3D WFALL-FIX to WF2-FIX 55 +/- 1 285D +/- 0.3D WFALL-FIX to PC1-FIX 39 +/- 1 0D +/- 0.3D WFALL-FIX to APEX 14 +/- 1 0D +/- 0.3D APEX to WF4 53 +/- 1 90D +/- 0.3D APEX to WF3 53 +/- 1 180D +/- 0.3D APEX to WF2 53 +/- 1 270D +/- 0.3D APEX to PC1 25 +/- 1 0D +/- 0.3D a. WFALL-FIX is defined as the point 10x10 arcsec from the WFPC2 pyramid apex in the WFPC2 X-Y coordinate frame (see Figure 9.1 WFPC2 Aperture Coordinate System). APEX refers to the WFPC2 pyramid apex. This apex is close to the OTA optical axis. The U2-U3 coordinate frame is not centered at the OTA optical axis. b. The vector Separations are calculated from current estimates of the locations of the WFPC2, FGS, and STIS, and NICMOS apertures. These values can change with time. c. The Offset Angle is defined as the angle from the line connecting the two Science Instruments to the +U3 axis in the counterclockwise direction. These numbers are calculated from current estimates and reflect uncertainties of +/– 1 degree, except where greater uncertainties are indicated in the table. d. This value is representative of the STIS apertures. For details on specific STIS apertures, see the Pointing and Aperture web page: http://www.stsci.edu/instruments/stis Table 7.5 (cont): Approximate Separation and Orientations between Restricted Instrument Detectors Instrument Apertures Separation (arcsec) Offset Angle (degrees) NICMOS WFALL–FIX to NIC1 420 +/– 15 227D +/– 3D WFALL–FIX to NIC2 453 +/– 15 227D +/– 3D WFALL–FIX to NIC3 372 +/– 15 227D +/– 3D Visit-level Special Requirements 129 WARNING: For any detailed orientation requirements, please describe your requirements clearly in the proposal text and give angles and offsets. Please feel free to contact your Program Coordinator for assistance in preparing your orientations. The above tabulated values are meant to be representative, and because of instrument-specific details the value you need may differ. Please refer to the Pointing and Aperture web page for current values: http://www.stsci.edu/instruments/stis SAME ORIENTation AS <visit> Sometimes any orientation (or any orientation within the range of the ORIENT Special Requirement) is acceptable the first time an object is observed, but must then be the same for subsequent observations of that target. This Special Requirement requests that the exposures in the current visit be made at the same telescope roll angle as the observations specified in <visit>. If timing Special Requirements are also used, then an incompatibility may result or the observations may be difficult to schedule. Special Observation Requirements CVZ Requests that a visit be scheduled within the Continuous Viewing Zone. When this requirement is specified, observers are allowed the entire 96-minute orbit in which to schedule their observations, instead of restricting them to a visibility interval. Only observers with proposals approved by the TAC for CVZ-usage should use this Special Requirement. Caution: CVZ visits are limited to a few narrow scheduling opportunities during a Cycle. A detailed definition of the CVZ for Cycle 10 is given in the Call for Proposals. 130 Chapter 7: Special Requirements [Visit_Requirements and Note: The CVZ Special Requirement does not necessarily enforce scheduling in an uninterrupted manner. Observations could be scheduled in SAA impacted or earth occulted orbits if that would benefit the overall efficiency of the telescope. If it is required that all (or a subset) of the exposures be done without interruption, the exposure level Special Requirement SEQuence <exposure-list> NON-INTerruptible should be used. SCHEDulability <percentage> This Special Requirement allows the observer to adjust the amount of target visibility allowed in each orbit. The visibility at a given pointing varies throughout the year with the 56-day precessional cycle of the HST orbit. This variation is small at zero declination (about 4 minutes between best case and worst case) but increases sharply as the Continuous Viewing Zone is approached. There is a trade-off between visibility and schedulability: visits with longer visibilities allow more science to be packed into each orbit, but are harder to schedule because the long visibility may only be attainable for a few short intervals during the year. Visits with shorter visibilities are less efficient in terms of how much can be done in each orbit, but are easier to schedule. <Percentage> specifies the percent of HST orbits in which the visit should be schedulable. The higher the percentage, the shorter the visibility. For example, SCHED 40% would allow only enough visibility in each orbit for the visit to be schedulable in the best 40% of HST orbits. SCHED 100% would allow the least amount of time per orbit, but would ensure that the visit would “fit” in every available HST orbit. Schedulability values are only defined at 10% intervals, so percentages will be rounded to the nearest multiple of 10%. If this Special Requirement is not supplied, visits will default to 30% schedulability. <Percentage> values below 30% are not allowed. The SCHED Special Requirement may be necessary when an ORIENTation <angle1> TO <angle2> or BETWEEN <date1> AND <date2>) visit-level Special Requirement or a PHASE <number1> TO <number2> exposure-level Special Requirement is specified with a very small tolerance, restricting the visit to only a few days during the cycle. In this case <percentage> should be set to a high enough number to ensure that the visit can schedule in orbits within its time window. Servicing mission proposals (category SM2, SM3, etc.) need to be schedulable at any time in order to accommodate changes in the schedule. The default SCHED value for SM proposals is therefore 100%. Visit-level Special Requirements 131 PARallel (Available but Unsupported) Specifies that the current visit is to execute as a parallel. This Special Requirement is only needed for those situations where the ground system does not automatically set up the visit as a parallel. Visits that include spacecraft (S/C) mode exposures that also need to execute as a parallel typically will need this Special Requirement. Timing Requirements For examples of formats of times, see Introduction to Special Requirements: Syntax and Rules on page 112, and Table 7.1: Supported Formats for Visit Level Special Requirements. AFTER <date> Specifies that the visit must start after the date given by <date>. The capability to designate a specific exposure within a visit to start after a certain time is not supported by this Special Requirement; that case is intended to be handled by adjusting timing within the visit. AFTER <visit> [BY <time1> [TO <time2>]] Specifies that the visit must start after the indicated <visit>. The BY option allows specification of the time interval (and its allowable range) that must elapse between the start of the referenced visit and the start of the current visit. For example, AFTER 6 BY 7H TO 9H requests that the current visit start no earlier than 7 hours and no later than 9 hours after the start of visit 6. If the TO <time2> is omitted, <time1> will be considered a lower limit (e.g., AFTER 20 BY 3H indicates that 3 hours or more are required between the start of visit number 20 and the start of the current visit). The capability to designate a specific exposure within a visit to start after a certain time is not supported by this Special Requirement; that case is intended to be handled by adjusting timing within the visit. Note: If the difference between <time1> and <time2> is too small, the visit may be impossible to schedule. A difference of at least 90 minutes (about 1 orbit) is recommended. Also note that <time1> must be as long as the anticipated duration of the referenced visit. BEFORE <date> Specifies that the current visit must start before the <date> given. The capability to designate a specific exposure within a visit to start before a certain time is not supported by this Special Requirement; that case is intended to be handled by adjusting timing within the visit. 132 Chapter 7: Special Requirements [Visit_Requirements and BETWEEN <date1> AND <date2> Specifies that the current visit must start between <date1> and <date2>. For example, BETWEEN 14-SEP-1999 AND 21-SEP-1999 indicates that the visit must be started after 14 September 1999 and before 21 September 1999. The capability to designate a specific exposure within a visit to start at a certain time is not supported by this Special Requirement; that case is intended to be handled by adjusting timing within the visit. Multiple BETWEEN Special Requirements may be specified on a visit. The visit will be allowed to execute during any of the time intervals specified. For example, the combination of BETWEEN 14-SEP-1999 AND 21-SEP-1999 and BETWEEN 10-OCT-1999 AND 1-NOV-1999 means that the visit must be started either between 14 September 1999 and 21 September 1999, or between 10 October 1999 and 1 November 1999. Multiple BETWEEN intervals on the same visit may not overlap: all the other intervals must either end earlier than <date1> or start later than <date2>. Note: The BEFORE, AFTER <date>, and BETWEEN Special Requirements are mutually exclusive. A visit which specifies one may not specify either of the other two, although multiple BETWEENs are allowed. Note that any BEFORE or AFTER <date> may be replaced by a BETWEEN with a sufficiently early start date or late end date. However, AFTER <visit> may be combined with BETWEEN or BEFORE. GROUP <visit-list> WITHIN <time> Specifies that visits numbered in the <visit-list> must all start within the <time> given. If the interval given is shorter than the least interval possible, the visits will be scheduled as close together as possible. For example, GROUP 7–10 WITHIN 12H requests that visits 7 through 10 all start execution within a 12-hour interval. Note that GROUP WITHIN is only a timing Special Requirement, and it implies nothing about relative ordering. GROUP 7-10 WITHIN 12H could possibly execute in the order 10, 7, 9, 8, for example. PERIOD <time> AND ZERO-PHASE <date> Supplies the period and zero-phase for observations to be made at a specific phase of a periodically variable target. <time> is the period in days, hours, minutes or seconds, and <date> is the date of the zero-phase with respect to Visit-level Special Requirements 133 the Sun. Note that, while this requirement is at the visit level, the actual PHASE Special Requirement is on the exposure level. If a target has multiple periods which must be satisfied simultaneously, the PERIOD AND ZERO–PHASE Special Requirement should refer to the shorter of the two periods and the longer period can be specified using multiple BETWEEN Special Requirements that cover the next year and a half. Be sure to discuss this with your Program Coordinator. (Example: The target is a X-ray pulsar. The observation needs to occur in a particular phase of the 35-hour binary period as well as a particular phase of the 2-month on/off period. Use the PERIOD AND ZERO–PHASE Special Requirement for the 35-hour period and then specify the 2-month period with multiple BETWEENs.) SEQuence <visit-list> WITHIN <time> Specifies that visits numbered in the <visit-list> must start within the <time> given, and must be ordered according to their visit number. If the interval given is shorter than the least interval possible, the visits will be scheduled as close together as possible. For example, SEQ 7–10 WITHIN 10H means that visit 10 must begin execution within 10 hours of the start time of visit 7, with visits 8 and 9 executing between. SEQ does not change the order of visits. Note that visits are executed in order of their numbers, so SEQ 2, 1, 4 WITHIN and SEQ 1, 2, 4 WITHIN do the same thing. The following CAMPAIGN Special Requirement was to be implemented for RPS2 in Cycle 10, but by not installing the ASCS this ability for low background cannot take place for some time. The text below is only a placeholder until details are worked out. CAMPAIGN (Available-but-Unsupported) STIS-LOW-BACKGROUND The CAMPAIGN Special Requirement is to be used to indicate that a visit is to be scheduled during a specially-designated observing opportunity. Such opportunities are identified in the Call for Proposals as specific time periods in which particular observing conditions pertain. In Cycle 10 the only approved campaign is to achieve low background count rates with the STIS FUV-MAMA detector. Programs using the CAMPAIGN Special Requirement must have requested the specific campaign in the Phase 1 proposal and that request must have been approved by the TAC. This is indicated by a special keyword in the Phase 1 proposal. 134 Chapter 7: Special Requirements [Visit_Requirements and Conditional Requirements ON HOLD [FOR <visit-list>] Specifies that the current visit should not be executed without further guidance from the observer (such as with a Target of Opportunity program, for example). When the FOR <visit-list> is specified, the current visit is linked to follow all the visits in <visit-list> by at least sixty days. This will allow these visits to execute early enough in the Cycle to provide needed data. This Special Requirement should be used for early acquisitions: the acquisition image is taken in the visit in <visit-list>, and the ON HOLD visit will be modified later based on the acquisition data. Exposure-level Special Requirements The following Special Requirements apply to individual exposures within a visit. All instances of <exposure-list> or <exposure> refer only to exposures in the same visit as the exposure carrying the requirement. Target Acquisition Separate target acquisition exposures must be specified at the beginning of most visits, depending on the target and the science instrument used. Target acquisition exposures are used to remove coordinate uncertainties and to identify targets. Once a target acquisition has been performed, HST can move the target from aperture to aperture or move the aperture around the target (with slew accuracies of about 10 milliarcseconds) as long as the same guide stars can be used. Onboard acquisitions are automatically identified by the software. Acquisition exposures must still be specified, but no Special Requirement is needed or appropriate. Acquisition of a target using an offset target requires that both be defined in the Target List(s). The first exposure will be an onboard or interactive acquisition of a target from which the offset will be made. This target must be designated as an offset acquisition target by appending -OFFSET to the end of the target name (see Table 3.1: Designations of Special Targets). The appropriate offsets will automatically be made from this position to slew to the target of interest. Exposure-level Special Requirements 135 INTeractive ACQuisition (obsolete) INT ACQ is Restricted for Cycle 10, and should not be used at all. Interactive acquisitions may no longer be performed with HST. However, the same results can be achieved in other ways, and you should consult your Program Coordinator for more information. SAVE OFFSET <id> (Available but Unsupported) This requirement is used to save the results of a target acquisition sequence for use by one or more subsequent exposures, which are normally in different visits. SAVE OFFSET indicates that this exposure will generate a pointing correction (or “offset”) for future science exposures which specify USE OFFSET with the same <id>. The purpose of the SAVE OFFSET/USE OFFSET procedure is to allow more efficient and flexible scheduling of observations. This Special Requirement is especially useful for replacing INTeractive ACQuisitions, which are no longer supported. Unlike the former INTeractive ACQuisition Special Requirement, the SAVE OFFSET/USE OFFSET procedure is not considered a limited resource. It should be used whenever it is possible to leave at least 3 days between this exposure and the first science exposure which uses the acquisition (in some instances this time delay can be reduced to as little as three orbits). • Target acquisition time may be saved if repeated observations of the same target are planned for multiple visits. In the first visit, the relevant target acquisition exposure should include the SAVE OFFSET <id> Special Requirement. Subsequent visits to the same target do not require repeating the target acquisition procedure; these exposures can simply specify the USE OFFSET <id> Special Requirement. In either case, unless the RT ANALYSIS Special Requirement is placed on the same exposure, visits which use an offset will be scheduled at least 3 days after the initial SAVE OFFSET visit. This allows time for the data to be downlinked and analyzed. The offset may not be saved and used in the same visit. For exposures with modes beginning with “ACQ,” visits which use an offset will be scheduled at least 3 days after the initial SAVE OFFSET visit. The <id> is an alphanumeric string of up to six characters in length. No two SAVE OFFSET Special Requirements in a proposal may use the same 136 Chapter 7: Special Requirements [Visit_Requirements and <id>, and every <id> from a SAVE OFFSET exposure must be used in at least one USE OFFSET exposure IMPORTANT: Both SAVE OFFSET and USE OFFSET rely on accurate coordinate uncertainties in order to calculate slew times properly. Unspecified target coordinate uncertainties may lead to a failure in execution of USE OFFSET. Program Coordinators should ensure that target coordinate uncertainties have been provided by the observer and that they are accurate. USE OFFSET <id> (Available but Unsupported) This Special Requirement is used to apply the results of a previous target acquisition sequence (one that specified SAVE OFFSET with the same <id>). Only one USE OFFSET Special Requirement is allowed per exposure, but it is permissible to use multiple offset <id>’s in the same visit. STScI personnel will help determine the necessary offsets. These offsets may require a minute or two of target visibility time. As described under SAVE OFFSET, this Special Requirement is useful for replacing the former INTeractive ACQuisition. The observer is usually required to be present at STScI at the time the SAVE OFFSET exposure is taken to determine the offset. Please contact your Program Coordinator. Unless the SAVE OFFSET exposure also has the RT ANALYSIS Special Requirement, the SAVE OFFSET and USE OFFSET exposures must be in separate visits, and the visits will be scheduled at least 3 days apart. If the SAVE OFFSET exposure uses a mode beginning with “ACQ,” visits using an offset will be scheduled at least 3 days after the initial SAVE OFFSET visit. It is not possible to override this separation with an AFTER Special Requirement. The SAME ORIENTation Special Requirement is implicit and need not be specified directly. See the discussion on target orientation ( Target Orientation on page 119) for an explanation of the restrictions this places on how far apart the visits may be scheduled. If the exposure is on a moving target, the maximum target acquisition uncertainty must be specified in the solar-system target list ( Acquisition Uncertainty [Acq_Uncert] on page 75). If the exposure is on a fixed target, the position uncertainty in the fixed target list ( Required Accuracies of Target Positions on page 34) is used to determine the maximum offset. STScI will be unable to schedule corrections larger than this maximum offset, so too small an uncertainty may limit the usefulness of the USE OFFSET procedure. However, offsets larger than about 1 arcminute may Exposure-level Special Requirements 137 make scheduling difficult. If your observation requires a correction this large, contact your Program Coordinator. The <id> is an alphanumeric string of up to six characters in length, and must be identical to the <id> defined by the preceding exposure with the SAVE OFFSET Special Requirement. Note that the <id> need only be unique within the proposal. It is not possible to use offsets across multiple proposals. Target Position The patterns used with instruments to create dithers or mosaics fall within “target position,” but the details have been incorporated into a separate chapter because of the scope of the subject. See Chapter 8: Pointings and Patterns on page 153 POSition TARGet <X-value>, <Y-value> Specifies a non-default placement of the target, relative to the aperture fiducial point in the instrument field of view, for the current exposure, which must be on an external target. The X and Y positions are implicitly assumed to be in units of arcseconds (i.e. do not enter “arcsec” after each value). The X-Y coordinate system and the default positioning for each scientific instrument are defined in Part B of these Instructions. An aperture’s fiducial point is ordinarily close to the geometric center of that aperture. Details may be found in the Instrument Handbooks. Note that the fiducial point and geometric centers are significantly different for the WFPC2 RAMP filters in particular. Note that a POS TARG is a motion relative to the original pointing of the target, and so they are not cumulative. Note: Changing the pointing in this way can cause overheads to be repeated at each POS TARG pointing in the case of WFPC2. If a large number of pointings need to be obtained within one visibility period, it may be more efficient to use a pattern designed for this purpose; see Chapter 8: Pointings and Patterns on page 153. 138 Chapter 7: Special Requirements [Visit_Requirements and SAME POSition AS <exposure> SAME POSition AS <exposure>: Requests that the current exposure be done at the same position on the sky and with the same telescope roll as <exposure>. Note that <exposure> must be in the same visit as the current exposure. This requirement is implicit for exposures within a visit with the same aperture, target, and POS TARG combination. This requirement is used in many astrometric observations, so that the telescope doesn’t try to center successive targets in the astrometer pickle before observing it. For other instruments, SAME POS AS should be used sparingly and with caution. For example, SAME POS AS 1 will cause the spacecraft to return to the pointing of exposure 1. Thus if the current exposure has a different (non concentric) aperture from 1 and specifies SAME POS AS 1, the target will be placed in the aperture used by exposure 1, not the aperture currently requested. Further, specifying SAME POS AS an onboard acquisition exposure will undo the offsets determined in the acquisition process. SAME POS AS should not be used with WFPC2 exposures which use different partially-rotated filters. SAME POS AS <exposure> can be used if the pointing of an internal exposure is required to be the same as that of an external exposure in the same visit, or if the same orient needs to be maintained across different obsets in a single visit. NOTRACK In certain cases a program will observe a moving target, but without tracking it. For example, a fast-moving comet might be observed by first executing a guide star acquisition, to remove pointing uncertainty, followed by an observation on gyros to acquire the comet data. This should be done without tracking both to save time and to avoid unnecessary use of spacecraft hardware. The default is to track a moving target, but tracking can be turned off by specifying NOTRACK for each exposure as appropriate. NOTRACK has no effect on an exposure unless it is for a moving target. Exposure-level Special Requirements 139 Special Observation Requirements PARallel <parallel-exp-list> WITH <primary-exp-list> Specifies that the exposures in <parallel-exp-list> will execute in parallel with a sequence of exposures in <primary-exp-list>. Both <primary-exp-list> and <parallel-exp-list> must be replaced by either a single exposure number, or a range of exposure numbers separated by a hyphen. See Coordinated Parallels on page 105 for more details. SAA CONTOUR <model number>: (WFPC2 only) This specifies the contour of the South Atlantic Anomaly (SAA) to be used for scheduling this exposure. If this parameter is not provided, a default SAA contour appropriate to the SI will be selected. Observations that can tolerate higher radiation levels may benefit, through improved schedulability, from use of less restrictive models. The following model numbers (ordered from most to least restrictive) are allowed: SAA Model Instrument for which model is default 05 COSTAR 23 NICMOS 26 WFPC2 27 ACS/CCD 28 ACS/MAMA 24 STIS/CCD 25 STIS/MAMA 03 FOC 02 FGS 11 no avoidance More information on these models may be found at: http://www.sesd.stsci.edu/et/seu/seu.html 02 is the minimal FGS contour needed to avoid radiation at levels that would interfere with guide star lock. The default contours vary by SI but are more restrictive (meaning lower maximum radiation levels and longer SAA interruption times) than the 02 contour for all instruments. A value of 11 means the SAA constraint will be ignored entirely. This requires a drop to gyro control for the exposure (also see the discussions under PCS MODE Fine, PCS MODE Gyro, and DROP TO GYRO IF 140 Chapter 7: Special Requirements [Visit_Requirements and NECESSARY [NO REACQuisition]), even if the visit as a whole is done under FGS control. This Special Requirement is now Restricted for all SIs except WFPC2. SAA CONTOUR <model number>: (Restricted) This specifies the contour of the South Atlantic Anomaly (SAA) to be used for scheduling this exposure. If this parameter is not provided, a default SAA contour appropriate to the SI will be selected. Observations that can tolerate higher radiation levels may benefit, through improved schedulability, from use of less restrictive models. The following model numbers (ordered from most to least restrictive) are allowed: 05, 23, 26, 27, 28, 24, 25, 03, 02, 11 02 is the minimal FGS contour needed to avoid radiation at levels that would interfere with guide star lock. The default contours vary by SI but are more restrictive (meaning lower maximum radiation levels and longer SAA interruption times) than the 02 contour for all instruments. A value of 11 means the SAA constraint will be ignored entirely. This requires a drop to gyro control for the exposure (also see the discussions under PCS MODE Fine, PCS MODE Gyro, and DROP TO GYRO IF NECESSARY [NO REACQuisition], even if the visit as a whole is done under FGS control. This Special Requirement is now Restricted for all SIs except WFPC2. SPECial COMmanding [INSTR <name>] (Restricted) Use of this Special Requirement indicates that the proposer is requesting a capability which is currently beyond the ability of the ground system to support. The intended use of this parameter is for engineers and Instrument Scientists to be able to investigate conditions on the spacecraft using spacecraft capabilities which are not part of the ground system. Details of the requirements will need to be specified in the proposal text and/or in Visit and Exposure Specifications comments. Exposures with the Special Requirement SPEC COM may be split, which can result in there being insufficient time in which to complete the commanding. To prevent this, you are encouraged to use the Special Requirements NO SPLIT or SEQ NON-INT with SPEC COM exposures. A very limited subset of the SPECial COMmanding instructions can be specified directly by the proposer. The name of the special instruction to be used should be indicated by the value of <name>. The list of allowed instruction names is maintained by the System Engineering Team. The use Exposure-level Special Requirements 141 of any other SPECial COMmanding instruction will generate an error. Note that the optional specification INSTR, used when specifying a <name>, stands for "instruction," not "instrument." The need for a non-qualifying instruction (i.e., one not in the above list) should continue to be noted by specifying SPEC COM on the exposure line without adding INSTR <name>. Special Communications Requirements RT ANALYSIS Specifies that the current science exposure must be made available to the observer for analysis in real time. (See the Call for Proposals for a discussion of real-time observing.) Any science exposures whose execution depends upon a decision based on the real-time analysis should have RT ANALYSIS specified. The REQuires UPLINK Special Requirement may also be used with RT ANALYSIS to establish the ground-to-spacecraft link. The current exposure will be available for analysis at least 16 minutes (for fixed targets) prior to that uplink; the time is 24 minutes for moving targets. Usage of this Special Requirement is considered a limited resource and should only be used when necessary. Justification for its necessity should be included in the Real_Time_Justification text. Note that the exposures in the <exposure-list> must be in the same visit as the current exposure. REQuires UPLINK Indicates that a real-time command uplink is needed to execute this exposure. An uplink will be scheduled prior to the current exposure. This Special Requirement should be used with RT ANALYSIS to replace the capability formerly available with INTeractive ACQuisition (obsolete) and it should specifically identify which exposures need an uplink, assuming that the uplink already provided is not sufficient. This Special Requirement can also be used without RT ANALYSIS if the information which needs to be uplinked is not dependent on real-time analysis of HST data. Usage of this Special Requirement is considered a limited resource and should only be used when necessary. Justification for its necessity should be included in the Real_Time_Justification text. Note that for ALIGN mode exposures (with any configuration) that use REQ UPLINK, no Optional Parameters are allowed. 142 Chapter 7: Special Requirements [Visit_Requirements and REQuires EPHEMeris CORRection <id> Indicates that a correction for position errors due to moving-target and/or HST ephemeris uncertainty may be needed to execute the exposure. This Special Requirement is only valid for exposures with moving targets. The offset will be uplinked during an available (“generic”) uplink prior to the earliest exposure that uses it. The pointing correction may require a minute or two of target visibility time. An ephemeris correction is needed in two cases: 1. When observing an object within about 1 AU of the Earth. In this case, the uncertainty in the position of HST accumulated between the time the schedule is built and the time it is executed can cause the observation to miss the target. (The HST ephemeris is inaccurate by as much as 60 seconds, which translates into a positional error on the moving target). The offset can be easily calculated by STScI personnel in this case. 2. When observing an object with an uncertain ephemeris. In this case, updated positions may be used until shortly before the observation actually executes, even though the elements in the program are out of date. Again, STScI personnel can easily determine the proper offset. With moving targets, the maximum target ephemeris uncertainty must be specified in the solar-system target list (see Ephemeris Uncertainty [Ephem_Uncert] on page 75). STScI will be unable to schedule corrections larger than the maximum offset derived from this uncertainty, so too small an uncertainty may limit the usefulness of the REQ EPHEM CORR procedure. However, offsets larger than about 1 arcminute may make scheduling difficult. If your observation requires a correction this large, contact your Program Coordinator. The <id> is an alphanumeric string of up to six characters in length. Exposures with the same REQuires EPHEMeris CORRection ID (whether in the same visit or in different visits) will use the same offset and must be taken at the same orientation. If exposures in different visits use the same ID, the visits involved are all subject to the same scheduling restrictions as SAME ORIENTation AS <visit>. The SAME ORIENTation Special Requirement is implied across such a set of visits, and need not be specified directly. Note that REQ EPHEM CORR uses the uncertainties in target coordinates to determine the size of a possible offset maneuver. Therefore those uncertainties must be supplied accurately. Exposure-level Special Requirements 143 FORMAT [AN or FN or HN or PN] (Available but Unsupported) Specifies that engineering telemetry of the specified format will be obtained during an exposure. If FORMAT is specified, a legal value must be used. There is no default value for FORMAT. For FGS exposures, with FN or HN are allowed for FORMAT. For S/C mode exposures, any listed format is allowed. Note: For either FN or PN format, a maximum of 3 hours duration is allowed before having to return to either AN or HN format so that valid thermal data may be transmitted for at least 10 minutes. Timing Requirements AFTER BY <time> [TO <time2>] (Available but Unsupported) This Special Requirement, when specified on an exposure within a visit (as opposed to on a visit level), specifies the minimum amount of <time> between the start of the previous exposure and the current exposure’s start. This <time> should never be longer than one orbit. When a TO <time2> is added, it specifies the maximum time between the start of the previous exposure and the current exposure’s start. If the interval given is shorter than the least interval possible, the exposures will be scheduled as close together as possible. Also note that <time2> may not exceed 36 hours. If you plan to use this Special Requirement, please contact your Program Coordinator for further details and discussions. END ORBIT Specifies that the current exposure is expected to be the last in a visibility period. When the system attempts to expand exposures to take advantage of unused time at the end of the orbit, expansion will then begin with the END ORBIT exposure and work backwards (see below). When END ORBIT is specified on an exposure with Number_Of_Iterations > 1 (See “Number of Times to Iterate the Exposure [Number_of_Iterations]” in Chapter 5.), the END ORBIT requirement will be applied only to the last exposure in the series. There is no guarantee that the scheduling system will not insert exposures in a visibility period after the END ORBIT exposure. For this reason, END ORBIT should NOT be used to enforce time separations between exposures. If such a separation is needed, please contact your Program Coordinator to determine the best way to do it. 144 Chapter 7: Special Requirements [Visit_Requirements and EXPAND Allows the proposer to choose which exposures within an orbit will be expanded to take advantage of unused time at the end of the orbit (note that the exposures will be expanded to fill the orbit unless the MAXimum DURation [<time or percentage>] Special Requirement is also listed). If there is no EXPAND within the orbit, the last exposure in the orbit will be considered for expansion (up to an additional 20%) first, followed by the previous one and the one before that, etc. Exposures containing the EXPAND requirement are considered first for expansion. See the discussion of MINimum DURation [<time or percentage>] below for a list of types of exposures which cannot be expanded. LOW-SKY Requests that the current exposure be taken when the total background light is no more than 30% greater than the yearly minimum value of the zodiacal background for that target. To minimize Earth shine, the exposure will also be taken when the target is at least 40 degrees from the bright Earth. This limits visibility time to about 48 minutes per orbit. Efficiency and schedulability are reduced with this Special Requirement, but to a much lesser degree than with SHADOW. This Special Requirement may not be combined with SHADOW or used in a CVZ visit. MAXimum DURation [<time or percentage>] Allows the proposer to set limits on the expansion of exposures to take advantage of unused visibility. If the MAX DUR requirement is not given, exposures with the EXPAND requirement may be lengthened up to 120% of the specified exposure time. MAX DUR allows the proposer to increase or decrease this limit, and to apply it to exposures with EXPAND. If <time> is specified, the exposure will not be lengthened beyond <time>. If <percentage> is specified, (e.g., MAX DUR 125%), the exposure will not be lengthened beyond <percentage> of the specified exposure time. If <time or percentage> is omitted, the exposure will not be lengthened at all. MINimum DURation [<time or percentage>] Allows the proposer to limit shortening of exposures to allow them to fit in a visibility period. If the MIN DUR requirement is not given, exposures will not be shortened to less than 80% of the specified exposure time. MIN DUR allows the proposer to increase or decrease this limit. The exposure may be shortened until its duration is <time> but not further. If <time or percentage> is omitted, the exposure will not be shortened at all. If a percentage is used (e.g., MIN DUR 80%) the exposure will be shortened Exposure-level Special Requirements 145 until its duration is decreased to, at most, <percentage> of the specified exposure time. Note: the following types of exposures are never adjusted. The EXPAND, MAX DUR, and MIN DUR Special Requirements should not be specified on these. • All NICMOS exposures. • Exposures using the STIS in modes other than ACCUM (see Chapter 10: Space Telescope Imaging Spectrograph (STIS) on page 199). • Exposures using FGS TRANS Mode (see Chapter 11: Fine Guidance Sensors (FGS) on page 243). • Exposures with internal or EARTH-CALIB targets. • Exposures in a visit with a CVZ Special Requirement (see CVZ). • Exposures using NICMOS BRIGHTOBJ Mode. NO SPLIT Specifies that the current exposure should not be split for earth occultations and SAA passages. PHASE <number1> TO <number2> Requests that the exposure start in the specified phase range (<number1> to <number2>) of a periodic variation. <number1> and <number2> should be between 0.0 and 1.0. The PERIOD <time> AND ZERO-PHASE <date> used in the calculation should have been already entered at the visit level. With short periods, the phase range (difference between <number1> and <number2>) should be made as wide as possible to make scheduling easier. Note that Number_of_Iterations must be 1 if PHASE is specified SEQuence <exposure-list> NON-INTerruptible Specifies that exposures defined in the <exposure-list> be observed without gaps due to Earth occultation or SAA passages. Gaps between exposures may still be necessary to allow time for activities which are necessary to set up for the next exposure, such as pointing changes, readouts of the SI buffers, and SI reconfigurations. This requirement must be included for a series of FGS exposures which are to be executed within the same orbit. 146 Chapter 7: Special Requirements [Visit_Requirements and The exposure list should be a range of numbers separated by a hyphen, such as SEQ NON-INT 55-60. Note: If this requirement is placed on one exposure (e.g., SEQ 20 NON-INT) and Number_of_Iterations > 1, the sequence of subexposures will not be split. This is different from NO SPLIT, which only requires that none of the individual subexposures be split (but allows splitting between subexposures). SHADOW Requests that the current exposure be taken while HST is in the umbral shadow of the Earth. It is primarily useful when contamination by geocoronal emission (Lyman alpha, OI 1304Å, etc.) must be minimized. However, it does not minimize zodiacal light, which is the principal source of background at wavelengths longer than 3500Å (see the LOW-SKY Special Requirement). Exposures using this Special Requirement are limited to about 32 minutes per orbit (including overheads). Scheduling may only be feasible for a small percentage of the year. This Special Requirement is a limited resource and should only be used when necessary; most usages of SHADOW will have been approved by the TAC during the Phase 1 review process. This Special Requirement may not be combined with LOW-SKY or used in a CVZ visit. VISIBILITY INTERVAL NIC-CORON This Special Requirement will override the visibility interval normally computed for the visit. No pads will be added, nor will any adjustment be performed based on the target declination. This should not be used in conjunction with the CVZ or SCHEDulability <percentage> Special Requirement. This Special Requirement may only be used with NICMOS coronagraphic observations (i.e., with an aperture of NIC2-CORON). This Special Requirement is ordinarily implementation-only; see next page Implementation Special Requirements (Engineering) 147 Implementation Special Requirements (Engineering) Visit Special Requirements (Engineering) VISIBILITY INTERVAL <time> This Special Requirement will override the visibility interval normally computed for the visit. No pads will be added, nor will any adjustment be performed based on the target declination. This should not be used in conjunction with the CVZ or SCHEDulability <percentage> Special Requirements. This Special Requirement may also have the value NIC-CORON and be used in a fully supported mode by GOs. See the previous page. Exposure Special Requirements (Engineering) NEW OBSET [FULL ACQ] NEW ALIGNMENT These Special Requirements will override the normal decision of whether an exposure will be merged into the same alignment or OBSET as the previous. Using it will force the exposure to start a new OBSET or alignment regardless of the existence or the criticality of any merging rules to the contrary (but error checking will be performed). In addition, it is possible to force a full guide star acquisition at the beginning of an obset, even if TRANS would not insert one there. The syntax for this capability is NEW OBSET FULL ACQ. SAME OBSET <exposure-list> This Special Requirement will override the normal decision of whether the exposures in the same list will be merged into the same OBSET. Using it will force the exposures in <exposure-list> to be included in the same OBSET regardless of the existence or the criticality of any breaking rules to the contrary (but error checking will be performed). Note that this differs from the SAME GUIDE STARS Special Requirement, which does not necessarily place any requirements on how exposures are to be arranged into obsets. 148 Chapter 7: Special Requirements [Visit_Requirements and SAME ALIGNMENT <exposure-list> [DONT SPLIT] This Special Requirement will override the normal decision of whether the exposures in the same list will be merged into the same alignment. Using it will force the exposures in <exposure-list> to be included in the same alignment regardless of the existence or criticality of any breaking rules to the contrary (but error checking will be performed). The exception is that the alignment may be split if it exceeds the time constraints of the visibility period. If this splitting needs to be suppressed, the DONT SPLIT option should be added at the end of this Special Requirement. Note that this differs from the SEQ NON-INT Special Requirement, which is purely a timing requirement (it requires exposures not to be separated by earth occultation), and does not necessarily place any requirements on how exposures are to be arranged into alignments. SAME GUIDE STARS <exposure-list> This Special Requirement will override the normal decision of whether two obsets must share the same set of guide stars. If two members of <exposure-list> are placed in different obsets, those two obsets will be forced to share the same guide stars regardless of the existence or criticality of any rules which would otherwise assign them separate guide star sets. GSPAIR <pair-id-> This Special Requirement will tell NGSS to use the specific guide star pair indicated. For pairs, <pair-id> is the 24-character NGSS guide star pair id and is of the form nnnnnnnnnnFdmmmmmmmmmmFe, where nnnnnnnnnn and mmmmmmmmmm are the 10-digit guide star ids of the two stars, and the Fs are required. d and e are the FGS numbers that the stars are to appear in (i.e., 1, 2, or 3). Note that the ordering of the stars is as NGSS will construct the pair. For singles, <pair-id> is as above except mmmmmmmmmm = ‘0000000000’ and e = ‘0.’ OBSET ID <id> This allows a non-default OBSET id to be chosen. <id> must be a two-character alphanumeric string and may be specified only once per obset. EXP PCS MODE [FINE | GYRO] These Special Requirements allow the PCS requirements for a particular exposure to be overridden. The PCS mode for an OBSET is still computed based on the most restrictive PCS mode in that OBSET. Therefore, in order Implementation Special Requirements (Engineering) 149 to override the PCS mode for an entire OBSET with a less restrictive value, it is necessary to place this Special requirement on every exposure within the OBSET, or it should be used at the Visit level. It is possible for an alignment to be executed on GYRO in an OBSET that uses FGS guiding. If EXP PCS MODE GYRO is included on every exposure within an alignment, it will be executed using gyro guiding, even if it is included in an OBSET which uses FGS guiding. These may also be entered as EXP PCS MODE F and EXP PCS MODE G. GS ACQ SCENARIO [PAIR | SINGLE | GYRO | <scenario>] This Special Requirement allows the guide star acquisition scenario for an obset to be overridden. This may be specified only once per obset. 150 Chapter 7: Special Requirements [Visit_Requirements and The following are legal values for the scenario: • BASE1: Fine lock, 1 pair • BASE2: Fine lock, 2 pairs • ONEB1: Fine lock, single star • COARSE1: Coarse track, 1 pair (requires special permission) • ONEC1: Coarse track, single star (requires special permission) • GYRO: Gyro guiding • PAIR: Use default pair scenario (BASE1) SINGLE: Use default single star scenario (ONEB1). CHAPTER 8: Pointings and Patterns For an explanation of this engineering-only version, see Special Note to Engineering Version Users in Chapter 1: About This Document on page 3. In this chapter . . . Pointing the Telescope / 153 Introduction to Patterns / 154 How to Fill Out the Pattern Parameters Form / 155 Pattern Parameters / 156 Convenience Patterns / 159 WFPC2 Patterns / 160 STIS Patterns / 162 ACS Patterns (for Cycle 11) / 165 NICMOS Patterns (for Cycle 11) / 167 Pointing the Telescope Acquiring an astronomical target and keeping it fixed in an aperture is the heart of observing with HST. Properly specifying target coordinates and motions is essential, of course, as is finding and acquiring suitable guide stars. Earlier chapters in this document have provided detailed instructions on how to specify coordinates and acquisitions for both fixed and moving targets; see Chapter 3: Fixed and Generic Targets [Generic _Targets] on page 23 and Chapter 4: Solar System Targets List [Solar_System_Targets] on page 59. 153 154 Chapter 8: Pointings and Patterns Introduction to Patterns Only rarely does an observer ask to look at precisely one point on the sky. Instead, small-scale repositionings of the aperture may be made to fully sample a region spatially, or larger-scale movements may be made to mosaic a region of the sky. These movements are known as patterns. In the past we have defined patterns on an case-by-case basis in a manner that seemed appropriate to each instrument. In rewriting the software that transforms your Phase 2 program into detailed observations, we realized that these different patterns were sometimes contradictory and incompatible, and that a common basis for describing patterns was needed for the current and future instruments. At the same time, we do not wish to further confuse observers by abandoning terms they may be familiar with, especially if they have continuing programs that could be affected by a change at an arbitrary time. Here is described this new patterns syntax, which provides both general capabilities and pre-defined “convenience” patterns. A pattern is specified as an exposure-level Special Requirement: PATTERN <#> [<exposure-list>] This specifies that each exposure in <exposure-list> (or the current exposure if no <exposure-list> is provided) should be repeated at each point in a pattern of discrete pointing offsets from the target. The <#> should be an integer between 1 and 999 that corresponds to the Pattern_Number of a pattern defined in the Pattern_Data block of the RPS2 file. Details for providing Pattern_Data are given in the next section. If the exposures in the <exposure-list> contain other expansion constructs (such as Number_of_Iterations > 1 or one of the CR-SPLIT Optional Parameters), the multiple exposures will be taken at each pattern point. If the <exposure-list> contains coordinated parallels, it must contain the entire parallel sequence (both <parallel-exp-list> and <primary-exp-list> from the PARALLEL WITH Special Requirement; see PARallel <parallel-exp-list> WITH <primary-exp-list>), and only those exposures. All parallel exposures will be taken at each pattern point. Only one PATTERN Special Requirement is allowed within any sequence. All primary exposures in <exposure-list> must have the same initial pointing: i.e., the same instrument configuration, aperture, target, and POS TARG offsets (if any). Patterns may be specified for a moving target. In this case the pattern is taken while the target is being tracked and the offsets obtained will be a How to Fill Out the Pattern Parameters Form 155 combination of target motion and motion imposed by the pattern relative to the target. The following exposure-level Special Requirement is not allowed on an exposure that is part of a pattern: • SAME POSition AS <exposure> Patterns are also not allowed with FGS TRANS mode (which specifies a separate scan with the FGS star selectors). How to Fill Out the Pattern Parameters Form The Pattern Parameters Form allows a pattern of pointing offsets to be defined. Patterns are useful for several different purposes: dithering to remove the effects of detector artifacts or to increase spatial resolution, mosaicing to cover a larger area on the sky, or moving away from the target to sample the background. Patterns are identified by the Pattern_Number field under the Pattern_Data block in the RPS2 file. The value of Pattern_Number must be an integer between 1 and 999. If an exposure anywhere in the proposal uses the PATTERN <#> [<exposure-list>] Special Requirement and <#> matches Pattern_Number, the specified exposures will be repeated at each point of the pattern. It is also possible to specify two nested patterns for an exposure or set of exposures. In this case, instead of taking the exposures at each point of the first pattern, the entire Secondary_Pattern will be executed at each point, creating a two-dimensional matrix of pointing offsets. The parameters for the first pattern appear under the Primary_Pattern label in the RPS2 template. If a second pattern is to be used, a similar Secondary_Pattern label followed by the same set of parameters should be added below the first. You do not need to specify a Secondary_Pattern unless you wish to, and you may delete it from your template The Pattern Parameters form looks like this in your RPS2 file: Pattern_Data Pattern_Number:11 !unique identifier Primary_Pattern: Pattern_Type:WFPC2-BOX Pattern_SI:WFPC2 Pattern_Shape:PARALLELOGRAM 156 Chapter 8: Pointings and Patterns Pattern_Purpose:DITHER Number_of_Points:4 Point_Spacing:0.559 Coordinate_Frame:POS-TARG Pattern_Orient:26.565 Center_Pattern:? Not all fields are required in all cases (see the examples below), and for some patterns both a Primary_Pattern and a Secondary_Pattern must be described. If none of the instrument-specific patterns will work, it is also possible to specify more generic lines and spirals. Pattern Parameters The Pattern Parameters Form has the following fields: Pattern_Number A unique identifier from 1 to 999. Pattern_Type This specifies the type of pattern (generally an instrument-specific name), and, depending on the type, may constrain or completely determine the values of the other parameters. Many pattern types have been defined for the different instruments, as given below. Pattern parameters that are determined by the pattern type, or have default values, need not be entered in the RPS2 file. Some pattern types are intended for use with a combination of two patterns (Primary_Pattern and Secondary_Pattern). With such pattern types the Secondary_Pattern is mandatory. The Pattern_Type may specify that a parameter of the Secondary_Pattern is constrained or determined by the value of the corresponding parameter of the Primary_Pattern. Whenever two patterns are used, the Pattern_Type of the Secondary_Pattern defaults to the pattern type of the Primary_Pattern, so it is not necessary to enter it under Secondary_Pattern. A Pattern_Type defined for a particular instrument is legal only if the first primary exposure in the pattern uses that instrument. Generic pattern types are valid with any instrument. Patterns specific to individual instruments are described in the next section; see Convenience Patterns on page 159. The following are generic pattern types. • Pattern_Type: LINE This specifies a linear pattern of offsets, with all other parameters open. How to Fill Out the Pattern Parameters Form 157 • Pattern_Type: SPIRAL This specifies a spiral pattern, with all other parameters open. Pattern_SI (Implicit parameter passed to the PP) This is the instrument to which the pattern type applies. GENERIC may be used if none of the convenience patterns below provides the needed capabilities. Pattern_Shape (Implicit parameter passed to the PP) This describes the geometric shape of the pattern, which must be one of three possibilities: LINE, SPIRAL, and PARALLELOGRAM. Pattern_Purpose This is a required text field which describes the scientific purpose of the pattern, but it is treated as a comment to help evaluate the Phase 2 program. There are four legal values: DITHER, MOSAIC, BACKGROUND, and OTHER: • DITHER means small-scale motions used to improve spatial resolution and data quality. • MOSAIC means movement of the aperture to sample different parts of an object or regions of sky. • BACKGROUND means a movement away from a source to sample the sky background, ordinarily used with infrared instruments. • If OTHER is used, the reason for the pattern should be provided in the visit or exposure comments. Unless a default is determined via the Pattern_Type, this parameter is required, although you may edit it from the default value to another valid value. Number_Of_Points This specifies the number of points in the pattern, from 1 to 50. Unless a default is determined via the Pattern_Type, this parameter is required. Point_Spacing This specifies the spacing between adjacent points in a pattern, in arcsec. For parallelogram patterns such as STIS-CCD-BOX, Point_Spacing will specify the length of the segment between the first two pattern points (the spacing between adjacent lines is determined by the Line_Spacing and is not user-specifiable). The value of Point_Spacing ranges from 0 to 1440 158 Chapter 8: Pointings and Patterns arcsec. Unless a default is determined via the Pattern_Type, this parameter is required. Note: patterns larger than about 130 arcsec (defined by the maximum pointing change between any two points in the pattern) may not be done on a single set of guide stars. For such patterns, unless the entire visit uses gyro guiding (PCS MODE Gyro; see PCS MODE Gyro), the visit-level Special Requirement DROP TO GYRO IF NECESSARY (see DROP TO GYRO IF NECESSARY [NO REACQuisition]) must be specified to allow the farther pattern points to execute under gyro guiding. Unless PCS MODE Gyro is specified on the visit, all patterns must be contained within a circle of radius 24 arcmin (1440 arcsec), with the first pattern point at the center. Line_Spacing (not a parameter that can be changed) This parameter is only relevant for PARALLELOGRAM patterns and specifies the distance between adjacent lines of the parallelogram in arcsec. This parameter is not user-specifiable, and is shown here only for informational purposes. Angle_Between_Sides (not a parameter that can be changed) This parameter also is only relevant for PARALLELOGRAM patterns and specifies the angle between sides of the parallelogram in degrees measured clockwise from the first pattern segment to the second. This parameter is not user-specifiable, and is shown here only for informational purposes. Coordinate_Frame This field has two legal values, POS-TARG and CELESTIAL. It specifies whether the pattern is being done in the POS TARG (spacecraft) frame or the celestial frame (by specifying offsets from the original target position on the sky). The default is POS-TARG, unless overridden via the Pattern_Type. For patterns with a Pattern_Purpose of DITHER, POS-TARG is the only legal value. Note: If the NICMOS OFFSET=FOM optional parameter is used, the pattern will be executed by moving the NICMOS Field Offset Mirror, rather than the telescope. In this case, Coordinate_Frame must be set to POS-TARG. All primary exposures in a pattern must use this parameter if any do, and all such exposures must specify the same set of values (if any) for the FOMXPOS and FOMYPOS Optional Parameters. Convenience Patterns 159 Pattern_Orient This field specifies the orientation of the first segment of the pattern with respect to the chosen frame, in degrees. If Coordinate_Frame: POS-TARG, this angle will be measured from the POS TARG +X axis toward the +Y axis. If Coordinate_Frame: CELESTIAL, it will be measured North through East, and will specify the direction of an offset from the target on the sky. Unless overridden via the Pattern_Type, the default value for Pattern_Orient is 0. This will cause the first pattern segment to be oriented along the POS TARG +X axis if Coordinate_Frame: POS-TARG, and along the North vector on the sky if Coordinate_Frame: CELESTIAL. Center_Pattern This indicates whether the pattern should be centered relative to the pointing (hereafter referred to as the “default pointing”) that the exposures would have had in the absence of a pattern. For a primary pattern (Primary_Pattern), the default pointing is the target position, unless the POS TARG Special Requirement (see POSition TARGet <X-value>, <Y-value>) is used to shift the target relative to the aperture. For a secondary pattern (Secondary_Pattern), the default pointing is the pointing offset from the target determined by the given pattern point in Primary_Pattern. Legal values for Center_Pattern are YES and NO. The default is NO, unless overridden via the Pattern_Type. If Center_Pattern: NO, the first pattern point is placed at the default pointing. If Center_Pattern: YES, the first pattern point is offset so that the default pointing is placed at the geometric center of the pattern. Convenience Patterns To minimize confusion, the following patterns use the new syntax but have been constructed to duplicate the earlier pattern forms. Their nomenclature is meant to be obvious, so that “WFPC2-LINE” means the former “LINE” pattern for WFPC2, for example. After each description we show what the RPS2 entries would look like. A specific entry for a parameter (such as 0.559 for Point_Spacing with WFPC2-BOX) means that value may not be changed and doing so will cause an error. An indicated range (such as 2-10 for Number_of_Points in WFPC2-LINE) means you may select from within that range, and a “?” means any numeric value may be entered. 160 Chapter 8: Pointings and Patterns As noted above, you may also nest patterns, but not all combinations make sense. In the first place, if you use both a Primary_Pattern and a Secondary_Pattern, they should be for the same instrument or at least one should be generic. Do not mix instrument-specific patterns. We have shown below which other patterns may validly be used as a Secondary_Pattern when the indicated one is the Primary_Pattern. When both a Primary_Pattern and a Secondary_Pattern are shown for a given Pattern_Type, both must be used. WFPC2 Patterns Note that these new patterns move HST in the opposite direction to the previously-provided WFPC2 patterns. Consult the WFPC2 Instrument Handbook for more information. To see an illustration of the WFPC2 POS-TARG reference frame, go to WFPC2 Aperture Coordinate System on page 197. Pattern_Type: WFPC2-LINE This produces a single-line scan, with its default orientation along a 45-degree diagonal with respect to the pixels of the primary camera. The default and strongly recommended single-line dither scan is a two-point scan with a spacing of 0.3535 arcsec between points. This yields an offset of (2.5, 2.5) pixels in the WFC CCDs and (5.5, 5.5) pixels in the PC. This default offset is optimized for resolution enhancement. If these defaults are not acceptable, the Number_Of_Points, Point_Spacing, and Pattern_Orient parameters may be used to vary the spacing and number of points along the line, and to change the orientation of the line. For example, observers interested only in removing CCD artifacts may prefer to use an integral-pixel offset, as this will simplify the data analysis. An example of an integral-pixel line dither is Point_Spacing: 0.707, which provides offsets of (5,5) pixels in the WFC CCDs and (11,11) pixels in the PC. Please discuss the use of these parameters with your Contact Scientist. Pattern_Type: WFPC2-LINE Pattern_Purpose:DITHER Number_of_Points:2-10 (default 2) Point_Spacing:0.01-3.0 (default 0.3535) Coordinate_Frame:POS-TARG Convenience Patterns 161 Pattern_Orient:? (default 45) Center_Pattern:? Permitted Secondary_Pattern values: LINE, SPIRAL. +Y POS-TARG PATTERN_TYPE=WFPC2-LINE 1 2 3 .. . Number_Of_Points +X POS-TARG Pattern_Type: WFPC2-BOX This will produce a four-point parallelogram scan. The four points of the parallelogram will be obtained at the following POS TARG (X,Y) offsets relative to the default aperture position: (0.0", 0.0") (0.5", 0.25") (0.75", 0.75") (0.25", 0.5") This default box pattern produces offsets on 0.25 arcsec centers, which represent 2.5 WFC pixels and 5.5 PC pixels. These offsets are optimized for resolution enhancement. If a box-type pattern other than this recommended parallelogram is desired, the POSition TARget special requirement may be used; see POSition TARGet <X-value>, <Y-value>. The Pattern_Purpose for WFPC2-BOX is DITHER. The Number_Of_Points is 4. The Point_Spacing is 0.559 arcsec. The Coordinate_Frame is POS-TARG. The Pattern_Orient is fixed at 26.565 degrees. Pattern_Type:WFPC2-BOX Pattern_Purpose:DITHER Number_of_Points:4 Point_Spacing:0.559 Line_Spacing:0.559 (may not be changed) Angle_Between_Sides:143.13 (may not be changed) Coordinate_Frame:POS-TARG Pattern_Orient:26.565 Center_Pattern:? Permitted Secondary_Pattern values: LINE, SPIRAL. To see an illustration of the WFPC2 POS-TARG reference frame, go to WFPC2 Aperture Coordinate System on page 197. 162 Chapter 8: Pointings and Patterns +Y POS-TARG PATTERN_TYPE=WFPC2-BOX 3 4 +X POS-TARG 2 1 STIS Patterns To see an illustration of the STIS POS-TARG reference frame, go to STIS Coordinate System on page 232. Pattern_Type: STIS-PERP-TO-SLIT This is normally used with a spectroscopic slit. It produces a scan along the POS TARG X-axis of the aperture; this is used to map a two-dimensional region of the sky (see Chapter 11 of the STIS Instrument Handbook). The target is moved perpendicular to the slit along the AXIS1 (dispersion) direction. Pattern_Type:STIS-PERP-TO-SLIT Pattern_Purpose:MOSAIC Number_of_Points:? Point_Spacing:? Coordinate_Frame:POS-TARG Pattern_Orient:0 Center_Pattern:? Permitted Secondary_Pattern values: STIS-ALONG-SLIT, LINE. +Y POS-TARG PATTERN_TYPE=STIS-PERP-TO-SLIT 1 +X POS-TARG 2 3 ... Number_Of_Points Convenience Patterns 163 Pattern_Type: STIS-ALONG-SLIT This is also normally used with a spectroscopic slit. It produces a scan along the POS TARG Y-axis of the aperture; this is used to step a target along the long slit to dither bad pixels or improve spatial resolution (see the STIS Instrument Handbook). The target is moved along the slit in the AXIS2 (cross-dispersion) direction. Pattern_Type:STIS-ALONG-SLIT Pattern_Purpose:DITHER Number_of_Points:? Point_Spacing:? Coordinate_Frame:POS-TARG Pattern_Orient:90 Center_Pattern:? Permitted Secondary_Pattern values: none. To see an illustration of the STIS POS-TARG reference frame, go to STIS Coordinate System on page 232. +Y POS-TARG PATTERN_TYPE=STIS-ALONG-SLIT +X POS-TARG ... Number_Of_Points 3 2 1 Pattern_Type: STIS-CCD-BOX This will produce a four-point parallelogram scan designed for dithering across the CCD pixels. With the default Point_Spacing of 0.567, the four points of the parallelogram will be obtained at the following POS TARG (X,Y) offsets relative to the default aperture position: (0.0", 0.0") (0.5070", 0.2535") (0.7605", 0.7605") (0.2535", 0.5070") This default produces a parallelogram pattern (see diagram) with projected offsets from the starting point of 5n integer pixels in each coordinate, so that the above arcsec values correspond to pixel values of (0, 0), (10, 5), (15, 15), and (5, 10). With these integer-pixel offsets, the pattern is optimized to simultaneously compensate for hot pixels and small-scale detector non-uniformities. The pattern can be rescaled (e.g., by a factor of 164 Chapter 8: Pointings and Patterns 0.5) to achieve shifts of N+half pixels for resolution enhancement by changing the Point_Spacing. Pattern_Type:STIS-CCD-BOX Pattern_Purpose:DITHER Number_of_Points:4 Point_Spacing:0.0567-5.67 (default 0.567) Line_Spacing:Equal to Point_Spacing Angle_Between_Sides:143.1 Coordinate_Frame:POS-TARG Pattern_Orient:? (default 26.6) Center_Pattern:? Permitted Secondary_Pattern values: none. To see an illustration of the STIS POS-TARG reference frame, go to STIS Coordinate System on page 232. PATTERN_TYPE=STIS-CCD-BOX PATTERN_TYPE=STIS-MAMA-BOX +Y POS-TARG 3 4 +X POS-TARG 2 1 Pattern_Type: STIS-MAMA-BOX This will produce a four-point parallelogram scan designed for dithering across the MAMA pixels. With the default Point_Spacing of 0.275, the four points of the parallelogram will be obtained at the following POS TARG (X,Y) offsets relative to the default aperture position: (0.0", 0.0") (0.246", 0.123") (0.369", 0.369") (0.123", 0.246") This default produces a parallelogram pattern (see diagram) with projected offsets from the starting point of 5n integer pixels in each coordinate, so that the above arcsec values correspond to pixel values of (0, 0), (10, 5), (15, 15), and (5, 10). With these integer-pixel offsets, the pattern is optimized to simultaneously compensate for hot pixels and small-scale detector non-uniformities. The pattern can be rescaled (e.g., by a factor of 0.5) to achieve shifts of N+half pixels for resolution enhancement by changing the Point_Spacing. Pattern_Type:STIS-MAMA-BOX Pattern_Purpose:DITHER Number_of_Points:4 Point_Spacing:0.0275-2.75 (default 0.275) Convenience Patterns 165 Line_Spacing:Equal to Point_Spacing Angle_Between_Sides:143.1 Coordinate_Frame:POS-TARG Pattern_Orient:? (default 26.6) Center_Pattern:? Permitted Secondary_Pattern values: none. Pattern_Type: STIS-SPIRAL-DITH This produces a spiral dither pattern, starting at the center and moving outward counterclockwise. Note that a STIS-SPIRAL-DITH with four points yields a square pattern, but the optimum pattern for detector dithering to enhance resolution is either STIS-CCD-BOX or STIS-MAMA-BOX. Pattern_Type:STIS-SPIRAL-DITH Pattern_Purpose:DITHER Number_of_Points:? Point_Spacing:? Coordinate_Frame:POS-TARG Pattern_Orient:? (default 0) Center_Pattern:? Permitted Secondary_Pattern values: none. To see an illustration of the STIS POS-TARG reference frame, go to STIS Coordinate System on page 232. +Y POS-TARG +X POS-TARG PATTERN_TYPE=STIS-SPIRAL-DITH 17 16 15 14 13 18 5 4 3 12 19 6 20 7 8 9 10 21 22 23 24 25 11 2 1 ACS Patterns (for Cycle 11) Pattern_Type: ACS-DITHER-LINE This specifies a linear pattern of offsets for ACS dithering. 166 Chapter 8: Pointings and Patterns Pattern_Type:ACS-DITHER-LINE Pattern_Purpose:DITHER Number_of_Points:2-9 (default 2) Point_Spacing:0.025-5.0 (default 0.283) Coordinate_Frame:POS-TARG Pattern_Orient:? (default 45) Center_Pattern:? Permitted Secondary_Pattern values: none. Pattern_Type: ACS-DITHER-BOX This specifies a box pattern for ACS dithering. Pattern_Type:ACS-DITHER-BOX Pattern_Purpose:DITHER Number_of_Points:4 Point_Spacing:0.025-5.0 (default 0.5) Line_Spacing:Equal to Point_Spacing Angle_Between_Sides:90 Coordinate_Frame:POS-TARG Pattern_Orient:? (default 53.13) Center_Pattern:? Permitted Secondary_Pattern values: none. Pattern_Type: ACS-WFC-MOSAIC-LINE This specifies a linear pattern of offsets for ACS mosaicing. Pattern_Type:ACS-WFC-MOSAIC-LINE Pattern_Purpose:MOSAIC Number_of_Points:2-9 (default 2) Point_Spacing:20-240 (default 80) Coordinate_Frame:POS-TARG Pattern_Orient:? (default 0) Center_Pattern:? Permitted Secondary_Pattern values: ACS-DITHER-BOX, LINE, SPIRAL. ACS-DITHER-LINE, Pattern_Type: ACS-HRC-SBC-MOSAIC-LINE This specifies a linear pattern of offsets for ACS mosaicing. Pattern_Type:ACS-HRC-SBC-MOSAIC-LINE Pattern_Purpose:MOSAIC Number_of_Points:2-9 (default 2) Point_Spacing:20-240 (default 20) Coordinate_Frame:POS-TARG Convenience Patterns 167 Pattern_Orient:? (default 0) Center_Pattern:? Permitted Secondary_Pattern values: ACS-DITHER-BOX, LINE, SPIRAL. ACS-DITHER-LINE, Pattern_Type: ACS-WFC-MOSAIC-BOX This specifies a box pattern for ACS mosaicing. Pattern_Type:ACS-WFC-MOSAIC-BOX Pattern_Purpose:MOSAIC Number_of_Points:4 Point_Spacing:20-240 (default 80) Line_Spacing:2*Point_Spacing Angle_Between_Sides:90 Coordinate_Frame:POS-TARG Pattern_Orient:? (default 0) Center_Pattern:? Permitted Secondary_Pattern values: ACS-DITHER-BOX, LINE, SPIRAL. ACS-DITHER-LINE, Pattern_Type: ACS-HRC-SBC-MOSAIC-BOX This specifies a box pattern for ACS mosaicing. Pattern_Type:ACS-HRC-SBC-MOSAIC-BOX Pattern_Purpose:MOSAIC Number_of_Points:4 Point_Spacing:20-240 (default 20) Line_Spacing:Equal to Point_Spacing Angle_Between_Sides:90 Coordinate_Frame:POS-TARG Pattern_Orient:? (default 0) Center_Pattern:? Permitted Secondary_Pattern values: ACS-DITHER-BOX, LINE, SPIRAL. ACS-DITHER-LINE, NICMOS Patterns (for Cycle 11) See the NICMOS Instrument Handbook for a full discussion of how and why to use patterns and for complete illustrations of their geometries. Pattern_Type: NIC-XSTRIP-DITH This specifies a linear pattern of offsets in the POS TARG +X direction. Pattern_Type:NIC-XSTRIP-DITH 168 Chapter 8: Pointings and Patterns Pattern_Purpose:DITHER Number_of_Points:? Point_Spacing:? Coordinate_Frame:POS-TARG Pattern_Orient:? (default 0) Center_Pattern:? Permitted Secondary_Pattern values: NIC-SPIRAL-DITH, NIC-SQUARE-WAVE-DITH, LINE, SPIRAL. NIC-YSTRIP-DITH, NIC-SPIRAL-MAP, Pattern_Type: NIC-YSTRIP-DITH This specifies a linear pattern of offsets in the POS TARG +Y direction. Pattern_Type:NIC-YSTRIP-DITH Pattern_Purpose:DITHER Number_of_Points:? Point_Spacing:? Coordinate_Frame:POS-TARG Pattern_Orient:? (default 90) Center_Pattern:? Permitted Secondary_Pattern values: NIC-SPIRAL-DITH, NIC-SQUARE-WAVE-DITH, LINE, SPIRAL. NIC-XSTRIP-DITH, NIC-SPIRAL-MAP, Convenience Patterns 169 +Y POS-TARG PATTERN_TYPE=NIC-XSTRIP-DITH 1 3 2 ... Number_Of_Points +X POS-TARG PATTERN_TYPE=NIC-YSTRIP-DITH PATTERN_TYPE=NIC-SPIRAL-DITH PATTERN_TYPE=NIC-SPIRAL-MAP ... Number_Of_Points 3 17 16 15 14 13 18 5 4 3 12 19 6 20 7 8 9 10 21 22 23 24 25 11 2 1 2 1 Pattern_Type: NIC-SPIRAL-DITH This specifies a spiral dither pattern. Pattern_Type:NIC-SPIRAL-DITH Pattern_Purpose:DITHER Number_of_Points:? Point_Spacing:? Coordinate_Frame:POS-TARG Pattern_Orient:? (default 0) Center_Pattern:? Permitted Secondary_Pattern values: NIC-YSTRIP-DITH, NIC-SQUARE-WAVE-DITH, LINE, SPIRAL. Pattern_Type: NIC-SPIRAL-MAP This specifies a spiral mosaic pattern. Pattern_Type:NIC-SPIRAL-MAP Pattern_Purpose:MOSAIC Number_of_Points:? Point_Spacing:? NIC-XSTRIP-DITH, NIC-SPIRAL-MAP, 170 Chapter 8: Pointings and Patterns Coordinate_Frame:CELESTIAL Pattern_Orient:? Center_Pattern:? Permitted Secondary_Pattern values: NIC-YSTRIP-DITH, NIC-SQUARE-WAVE-DITH, LINE, SPIRAL. NIC-XSTRIP-DITH, NIC-SPIRAL-DITH, Pattern_Type: NIC-SQUARE-WAVE-DITH This specifies a square-wave pattern with the “amplitude” of the square wave along the POS TARG +Y axis and the main direction of motion along the POS TARG +X axis. Pattern_Type:NIC-SQUARE-WAVE-DITH Pattern_Purpose:DITHER Number_of_Points:? Point_Spacing:? Line_Spacing:Equal to Point_Spacing Angle_Between_Sides:270 Coordinate_Frame:POS-TARG Pattern_Orient:? (default 90) Center_Pattern:? Permitted Secondary_Pattern values: NIC-XSTRIP-DITH, NIC-YSTRIP-DITH, NIC-SPIRAL-DITH, NIC-SPIRAL-MAP, LINE, SPIRAL. Pattern_Type: NIC-ONE-CHOP This requires two pattern definitions. It specifies a repeated “chop” back and forth along the POS TARG +X axis. Primary pattern: Pattern_Type:NIC-ONE-CHOP Pattern_Purpose:BACKGROUND Number_of_Points:? Point_Spacing:0 Coordinate_Frame:POS-TARG Pattern_Orient:0 Center_Pattern:NO Secondary pattern: Pattern_Type:NIC-ONE-CHOP Pattern_Purpose:BACKGROUND Number_of_Points:2 Point_Spacing:? Coordinate_Frame:POS-TARG Pattern_Orient:? (default 0) Convenience Patterns 171 Center_Pattern:NO Other permitted Secondary_Pattern values: none. Pattern_Type: NIC-TWO-CHOP This requires two pattern definitions. It specifies a repeated “chop” along the POS TARG +X axis, similar to NIC-ONE-CHOP, but using four points instead of two. Primary pattern: Pattern_Type:NIC-TWO-CHOP Pattern_Purpose:BACKGROUND Number_of_Points:? Point_Spacing:0 Coordinate_Frame:POS-TARG Pattern_Orient:0 Center_Pattern:NO Secondary pattern: Pattern_Type:NIC-TWO-CHOP Pattern_Purpose:BACKGROUND Number_of_Points:4 Point_Spacing:? Line_Spacing:Equal to Point_Spacing Angle_Between_Sides:0 Coordinate_Frame:POS-TARG Pattern_Orient:? (default 0) Center_Pattern:NO Other permitted Secondary_Pattern values: none. Pattern_Type: NIC-XSTRIP-DITH-CHOP This requires two pattern definitions. It specifies a combination of a line pattern and a two-point line at right angles (the “chop”). Primary pattern: Pattern_Type:NIC-XSTRIP-DITH-CHOP Pattern_Purpose:DITHER Number_of_Points:? Point_Spacing:? Coordinate_Frame:POS-TARG Pattern_Orient:? (default 0) Center_Pattern:? Secondary pattern: Pattern_Type:NIC-XSTRIP-DITH-CHOP Pattern_Purpose:BACKGROUND 172 Chapter 8: Pointings and Patterns Number_of_Points:2 Point_Spacing:? Coordinate_Frame:POS-TARG Pattern_Orient: (<Primary_Pattern value>+90) mod 360 Center_Pattern:NO Other permitted Secondary_Pattern values: none. Pattern_Type: NIC-YSTRIP-DITH-CHOP This requires two pattern definitions. It specifies a combination of a line pattern and a two-point line at right angles (the “chop”). Primary pattern: Pattern_Type:NIC-YSTRIP-DITH-CHOP Pattern_Purpose:DITHER Number_of_Points:? Point_Spacing:? Coordinate_Frame:POS-TARG Pattern_Orient:? (default 90) Center_Pattern:? Secondary pattern: Pattern_Type:NIC-YSTRIP-DITH-CHOP Pattern_Purpose:BACKGROUND Number_of_Points:2 Point_Spacing:? Coordinate_Frame:POS-TARG Pattern_Orient: (<Primary_Pattern value>-90) mod 360 Center_Pattern:NO Other permitted Secondary_Pattern values: none. Pattern_Type: NIC-SPIRAL-DITH-CHOP This requires two pattern definitions. It specifies a combination of a spiral pattern and a two-point line (the “chop”). Primary pattern: Pattern_Type:NIC-SPIRAL-DITH-CHOP Pattern_Purpose:DITHER Number_of_Points:? Point_Spacing:? Coordinate_Frame:POS-TARG Pattern_Orient:? (default 0) Center_Pattern:? Secondary pattern: Pattern_Type:NIC-SPIRAL-DITH-CHOP Convenience Patterns 173 Pattern_Purpose:BACKGROUND Number_of_Points:2 Point_Spacing:? Coordinate_Frame:POS-TARG Pattern_Orient: Equal to <Primary_Pattern value> Center_Pattern:NO Other permitted Secondary_Pattern values: none. Pattern_Type: NIC-MAP This specifies a linear mosaic pattern oriented on the sky. Primary pattern: Pattern_Type:NIC-MAP Pattern_Purpose:MOSAIC Number_of_Points:? Point_Spacing:? Coordinate_Frame:CELESTIAL Pattern_Orient:? Center_Pattern:? Secondary pattern: Pattern_Type:NIC-MAP Pattern_Purpose:MOSAIC Number_of_Points:? Point_Spacing:? Coordinate_Frame:CELESTIAL Pattern_Orient:? Center_Pattern:? Other permitted Secondary_Pattern values: none. Pattern_Type: NIC-SKY-ONE-CHOP This requires two pattern definitions. It specifies a pattern similar to NIC-ONE-CHOP, except that it is oriented on the sky. Primary pattern: Pattern_Type:NIC-SKY-ONE-CHOP Pattern_Purpose:BACKGROUND Number_of_Points:? Point_Spacing:0 Coordinate_Frame:CELESTIAL Pattern_Orient:0 Center_Pattern:NO Secondary pattern: Pattern_Type:NIC-SKY-ONE-CHOP 174 Chapter 8: Pointings and Patterns Pattern_Purpose:BACKGROUND Number_of_Points:2 Point_Spacing:? Coordinate_Frame:CELESTIAL Pattern_Orient:? Center_Pattern:NO Other permitted Secondary_Pattern values: none. Pattern_Type: NIC-SKY-TWO-CHOP This requires two pattern definitions. It specifies a pattern similar to NIC-TWO-CHOP, except that it is oriented on the sky. Primary pattern: Pattern_Type:NIC-SKY-TWO-CHOP Pattern_Purpose:BACKGROUND Number_of_Points:? Point_Spacing:0 Coordinate_Frame:CELESTIAL Pattern_Orient:0 Center_Pattern:NO Secondary pattern: Pattern_Type:NIC-SKY-TWO-CHOP Pattern_Purpose:BACKGROUND Number_of_Points:4 Point_Spacing:? Line_Spacing:Equal to Point_Spacing Angle_Between_Sides0 Coordinate_Frame:CELESTIAL Pattern_Orient:? Center_Pattern:NO Other permitted Secondary_Pattern values: none. Pattern_Type: NIC-SKY-XSTRIP-DITH-CHOP This requires two pattern definitions. It specifies a combination of a line pattern and a two-point line at right angles (the “chop”), similar to NIC-XSTRIP-DITH-CHOP except that the pattern is oriented on the sky. Primary pattern: Pattern_Type:NIC-SKY-XSTRIP-DITH-CHOP Pattern_Purpose:DITHER Number_of_Points:? Point_Spacing:? Coordinate_Frame:POS-TARG Convenience Patterns 175 Pattern_Orient:? Center_Pattern:? Secondary pattern: Pattern_Type:NIC-SKY-XSTRIP-DITH-CHOP Pattern_Purpose:BACKGROUND Number_of_Points:2 Point_Spacing:? Coordinate_Frame:CELESTIAL Pattern_Orient: (<Primary_Pattern value>+90) mod 360 Center_Pattern:NO Other permitted Secondary_Pattern values: none. Pattern_Type: NIC-SKY-SPIRAL-DITH-CHOP This requires two pattern definitions. It specifies a combination of a spiral pattern and a two-point line (the “chop”), similar to NIC-SPIRAL-DITH-CHOP except that the pattern is oriented on the sky. Primary pattern: Pattern_Type:NIC-SKY-SPIRAL-DITH-CHOP Pattern_Purpose:DITHER Number_of_Points:? Point_Spacing:? Coordinate_Frame:POS-TARG Pattern_Orient:? Center_Pattern:? Secondary pattern: Pattern_Type:NIC-SKY-SPIRAL-DITH-CHOP Pattern_Purpose:BACKGROUND Number_of_Points:2 Point_Spacing:? Coordinate_Frame:CELESTIAL Pattern_Orient:<Primary_Pattern value> Center_Pattern:NO Other permitted Secondary_Pattern values: none. 176 Chapter 8: Pointings and Patterns PART B: Supported Science Instruments The chapters in this part describe the configurations and modes for the three available instruments on HST for Cycle 10: WFPC2, STIS, and FGS. 177 178 CHAPTER 9: Wide Field Planetary Camera 2 (WFPC2) For an explanation of this engineering-only version, see Special Note to Engineering Version Users in Chapter 1: About This Document on page 3. In this chapter . . . Introduction to WFPC2 / 180 Mode = IMAGE Configuration = WFPC2 / 182 Mode = DECON Configuration = WFPC2 (Restricted) / 188 Mode = POM Configuration = WFPC2 (Restricted) / 189 Mode = AFM Configuration = WFPC2 (Restricted) / 190 Tabular Reference Data / 191 WFPC2 Internal Calibration Targets (Available but Unsupported) / 195 WFPC2 Aperture Coordinate System / 197 179 180 Chapter 9: Wide Field Planetary Camera 2 (WFPC2) Tables and Figures Table 9.1: Supported Instrument Parameters for WFPC2 Table 9.2: WFPC2 Apertures Table 9.3: Valid WFPC2 Exposure Times (seconds) Table 9.4: WFPC2 Supported Spectral Elements (Filters) Table 9.5: Linked Spectral Element/Aperture Combinations for Wood’s and Quadrant Filters Table 9.6: Internal Calibration Targets for the WFPC2 (Available but Unsupported) Figure 9.1 WFPC2 Aperture Coordinate System Introduction to WFPC2 The Instrument Configurations and Operating Modes described in the following section are used to specify exposures on the RPS2 Visit and Exposure Specifications. The legal Visit and Exposure Specifications entries are summarized in the following sections. More complete descriptions of Instrument Configurations, Modes, Apertures, Spectral Elements, Detector Characteristics, etc. are available in the WFPC2 Instrument Handbook. Note that many of the Optional Parameters have default values; in such cases, an entry for an Optional Parameter in the Visit and Exposure Specifications is necessary only if it is desired to override the default value. The physical units of Optional Parameter quantities are always implicit and should never be entered by the observer. Optional Parameters whose descriptions begin with the phrase “USE WITH CAUTION” pose a risk to the intended science if a non-default value is used inappropriately. These parameters are italicized in Table 9.1. You may wish to discuss the use of these parameters with your Contact Scientist. The following table lists the permitted Instrument Configurations, Operating Modes, Field of View, Spectral Elements, and Optional Parameters for the WFPC2. 181 Table 9.1: Supported Instrument Parameters for WFPC2 Config. Mode WFPC2 IMAGE Field of View Spectral Elements WF2, WF3, Enter any WF4, WFALL, Name from WF2-FIX, Table 9.4 WF3-FIX, WF4-FIX, WFALL-FIX, PC1, PC1-FIX, LRF, F160BN15, FQUVN33, FQCH4N33, FQCH4N15, FQCH4P15, FQCH4W2, FQCH4W3, FQCH4W4, POLQN18, POLQN33, POLQP15P, POLQP15W Optional Parameters ATD-GAIN, CR-SPLIT, CR-TOLERANCE, PRE-FLASH, SUM, CLOCKS, READ 182 Chapter 9: Wide Field Planetary Camera 2 (WFPC2) Table 9.1 (cont): Limited-Access Instrument Parameters for WFPC2 Config. Mode WFPC2 IMAGE DECON (Restricted ) POM (Restricted ) AFM (Restricted ) Field of View Spectral Elements Optional Parameters WF2, WF3, WF4, WFALL, WF2-FIX, WF3-FIX, WF4-FIX, WFALL-FIX, PC1, PC1-FIX, LRF, F160BN15, FQUVN33, FQCH4N33, FQCH4N15, FQCH4P15, POLQN33, FQCH4W2, FQCH4W3, FQCH4W4, POLQN18, POLQP15P, POLQP15W F160AN15 [same as IMAGE Mode] Enter any Name from Table 9.4 BLADE, CLEAR (Restricted) (none) (none) (none) (none) POM-X, POM-Y (Restricted) (none) (none) AFM1-X, AFM1-Y, AFM3-X, AFM3-Y, AFM4-X, AFM4-Y (Restricted) The sections on the following pages provide further details of the entries to be made on the Visit and Exposure Specifications when a particular WFPC2 configuration is chosen. Mode = IMAGE Configuration = WFPC2 The IMAGE Mode is the only one available to GOs with the WFPC2 configuration. The WFPC2 configuration provides the largest field of view of any instrument on HST. Three wide field CCDs (WF2–WF4) each provide a 800x800 pixel format with a pixel size of 0.10x0.10 arcsec at the center of each CCD. The planetary CCD (PC1) provides higher spatial 183 resolution and a correspondingly smaller field of view in a 800x800 pixel format with a pixel size of 0.046x0.046 arcsec at the center of the CCD. Each CCD has an approximately 40-pixel vignetted region (i.e., a blank area not exposed to the sky) at its adjoining edge which corresponds to the facets of the pyramid mirror. The composite WFPC2 FOV is shown in Figure 9.1: WFPC2 Aperture Coordinate System. See the WFPC2 Instrument Handbook for details. Aperture or FOV The specification of the FOV for the WFPC2 controls where the target is placed. The target will be placed at the default location (see below) within the specified FOV, unless the POSition TARGet exposure-level Special Requirement (see POSition TARGet <X-value>, <Y-value>) is used. The ORIENT visit-level Special Requirement (see ORIENTation <angle1> TO <angle2>) may be used to request a specific orientation of an extended scene in the WFPC2 FOV. Two types of apertures are defined for each CCD. The first type is designed for placing targets at the “optimum center” of the CCDs, based on the current performance of the CCDs. These are identified as WF2, WF3, WF4, WFALL, and PC1. The default location within these apertures will be routinely adjusted by STScI to reflect any changes in CCD performance (e.g., new charge transfer traps, bad columns, etc.). These apertures should be used for targets which are small compared to the scale size of defects in the chips (which are on the order of 10 pixels). The second set of apertures define the “geometric center” of the CCDs and will remain FIXED in aperture coordinates. They will NOT be adjusted for changes in CCD characteristics. These apertures are designated WF2–FIX through WF4–FIX, WFALL–FIX, and PC1–FIX. These apertures should be used to specify the location of the target relative to the CCDs. Pointings designed to position an extended scene within the WFPC2 FOV should normally be done with the “geometric center” set of apertures. At present WF3 is the only CCD for which the optimum and geometric centers differ. The WFPC2 X,Y coordinate system defined in Figure 9.1: WFPC2 Aperture Coordinate System is to be used for the POS TARG Special Requirement. Generally all four CCDs are read out even when only one CCD (e.g., WF2) is specified as the FOV. If data volume constraint problems are encountered during the planning and scheduling of your observations, you will be contacted by STScI to discuss subsetted CCD readouts. Subsetted CCD readout can be requested by the READ optional parameter. 184 Chapter 9: Wide Field Planetary Camera 2 (WFPC2) Table 9.2: WFPC2 Apertures Aperture Default position PC1 WF2 WF3 WF4 WFALL PC1-FIX WF2-FIX WF3-FIX WF4-FIX WFALL-FIX Optimum Center of PC CCD1 Optimum Center of WFC CCD2 Optimum Center of WFC CCD3 Optimum Center of WFC CCD4 Same as WFALL-FIX (see WFPC2 Instrument Handbook) Geometric center of PC CCD1 Geometric center of WFC CCD2 Geometric center of WFC CCD3 Geometric center of WFC CCD4 Approximately 14 arcsec from apex of pyramid on WFC CCD3 LRF This aperture is required when the LRF filter is specified as the spectral element. The target position will be derived from the central wavelength specified in the Visit and Exposure Specifications. F160AN15 These apertures should be specified when a partially rotated F160BN15, FQUVN33, spectral element of the same name is used. They are the optimum target positions based on the FOV/filter overlap and FQCH4N33, the response characteristics of the CCDs. See Table 9.5 for FQCH4N15, specific FOV/filter combinations which are supported. The FQCH4P15, positions of these apertures are shown in the WFPC2 FQCH4W2, Instrument Handbook. FQCH4W3, FQCH4W4, Note that only one partially-rotated filter may be POLQN18, POLQN33, specified as the spectral element for a given WFPC2 POLQP15P, exposure. POLQP15W Spectral Elements The Spectral Elements for the WFPC2 are listed in Table 9.4. If a partially-rotated filter is chosen, only one such spectral element may be specified for a given WFPC2 exposure. Wavelength For the LRF filter specification, the desired central wavelength of the filter passband must be specified. STScI will translate the specified wavelength to a filter orientation and default target position. For details on the mapping from wavelength to target position, see the WFPC2 Instrument Handbook or the WWW Linear Ramp Filter Calculator at: http://www.stsci.edu/instruments/wfpc2/Wfpc2_lrf/wfpc2_lrfc alc.html 185 Note that use of the LRF filter will cause an error if you impose the SAME POSition AS <exposure> Special Requirement because the desired wavelength is achieved by positioning the source in the LRF, which may conflict with SAME POS. For exposures using the quadrant transmission filters (FQUVN and FQCH4N), the central wavelength of the intended quadrant must be specified. It will be used as a consistency check on the aperture specified for the exposure. Optional Parameters ATD-GAIN =7 (default); 15 This parameter specifies the analog-to-digital gain of the CCD readout electronics in units of e-/DN. (See the WFPC2 Instrument Handbook for the exact gains of the readout electronics. ATD-GAIN=15 is really better approximated as 14 e-/DN, but for historical reasons the former number is used.) CLOCKS =NO (default); YES USE WITH CAUTION – When taking exposures containing saturated pixels, the observer can minimize the amount of image “blooming” by leaving the serial clocks running (CLOCKS=YES). This procedure minimizes the amount of transference of charge from one column to the next through the readout channel. Exposures obtained with serial clocks (CLOCKS=YES) must be equal to or longer than 1 second. Use of CLOCKS=YES is not generally recommended. For a full discussion, see the WFPC2 Instrument Handbook. CLOCKS=YES is ignored for exposures that use the INTFLAT and BIAS calibration targets. CR-SPLIT =DEF (default); range between 0.0 to 1.0; or NO All WFPC2 external exposures longer than 10 minutes will automatically be split into two exposures to allow for easier identification of cosmic-ray events. The two exposures will be of approximately equal length; the maximum deviation from equal length can be controlled via the CR–TOLERANCE parameter. If the default method of splitting the exposure is not acceptable, CR-SPLIT should be used to set the fraction of the exposure time that should be used for the first subexposure. Note: If the 186 Chapter 9: Wide Field Planetary Camera 2 (WFPC2) derived exposure time does not equal one of the discrete times in Table 9.3, the next lower value in the table will be used. CR-SPLIT=NO must be entered if the exposure should not be split. The number of exposures should not count these subexposures as separate exposures, so 1 should generally be entered for the Number_of_Iterations keyword. If multiple iterations are specified, the total number of exposures will be 2 * Number_Of_Iterations. If both subexposures are to be executed in the same orbit, the NO SPLIT exposure-level Special Requirement should be used on the Visit and Exposure Specifications line being split. CR-SPLIT values of 0.0 or 1.0 are not allowed. CR-TOLERANCE =0.2 (default); range from 0.0 to 1.0 CR-SPLIT exposures are split into two parts whose default lengths are nominally equal. Scheduling efficiency can sometimes be increased if the split is adjusted according to the scheduling situation. This parameter defines the amount of adjustment that the observer wishes to allow in the exposure ratio defined by CR-SPLIT. For example, the default value, 0.2, allows a CR-SPLIT value of 0.5 to vary between 0.3 and 0.7. PRE-FLASH (placeholder for future implementation) =NO (default); YES This parameter specifies whether the internal flat-field lamps should be used to provide a uniform low-level illumination before the exposure is taken. This preflash improves the photometric accuracy of exposures with very low signals by reducing the effect of the ‘Deferred charge.” It should generally be used whenever the sky background is less than about 4 DN. If PRE-FLASH=YES, about 14 DN preflash will be used (with an analog-to-digital gain of 7; if a gain of 15 is used then only about a preflash of 7 is needed. The preflash requires about two minutes to perform on the wide-field CCDs, and 3 minutes on the PC CCD. READ =YES (default); NO 1; 2; 3; 4; 1+2; 1+3; 1+4; 2+3; 2+4; 3+4; 1+2+3; 2+3+4; 1+3+4; 1+2+4 USE WITH CAUTION – The default is to read out all four CCDs for each exposure. Multiple exposures of a target on different parts of the same CCD image can be made without reading out each exposure (READ=NO). A different target position may be defined for each exposure by using the POSition TARGet exposure-level Special Requirement on subsequent exposures. The SEQuential NON-INT exposure-level Special Requirement must be included to link the exposures, minimizing 187 cosmic-ray and dark-count backgrounds and the final exposure must use READ=YES. Subsetted CCD readout can be requested by specifying the CCD or combination of CCDs to be read out. SUM =1X1 (default); 2X2 The default is to read out each individual pixel (1X1) resulting in a 1600x1600 format for the four CCDs (800x800 per CCD). A 2X2 pixel on-chip summation may be used, resulting in an 800x800 format for the four CCDs (400x400 per CCD). This reduces spatial resolution by a factor of two and increases signal-to-noise for cases where CCD readout noise is a large contribution to the error budget. BLADE (Restricted) =A, B Enter this optional parameter with either A or B if a specific shutter blade needs to be closed at the beginning of the exposure. The primary use of this option is to take an internal flat exposure with a particular shutter blade in place in order to derive the blade-dependent flat-field pattern. CLEAR (Restricted) =NO (default); YES This parameter specifies whether or not to clear the filters from the beam after an exposure is read out. Normally, filters are cleared as part of the next observation, not as part of the present observation. Number of Iterations The value entered is the number of times this Visit and Exposure Specifications line should be iterated. There are many observational situations when two or more exposures should be taken of the same field (e.g., to keep a bright object from “blooming” by keeping the exposure time short). See the WFPC2 Instrument Handbook for details. Time Per Exposure The value entered is the duration of the exposure. Although the possible exposure times for the WFPC2 are quantized (see the WFPC2 Instrument Handbook), an observer may enter any value for the exposure time. 188 Chapter 9: Wide Field Planetary Camera 2 (WFPC2) However, if that value does not equal one of the discrete times in Table 9.3, the next lower value in the table will be used. Since readout noise is present in the WFPC2, exposures are not split for scheduling reasons except as needed for cosmic-ray removal as described under CR-SPLIT. Remember that if CR-SPLIT is used, the total exposure time will actually be apportioned among two shorter exposures. See Table 9.6 for exposure times that should be entered for internal calibration targets. Mode = DECON Configuration = WFPC2 (Restricted) The DECON mode allows the specification of periods of time during which the WFPC2 should be in a contamination–removal configuration. The thermo–electric coolers are turned off and the CCD heaters and heatpipe heaters are turned on, allowing the detectors to warm up and so drive off any contamination that might be on the detector surfaces. This Mode does not collect any science data from the WFPC2. Target Name ORBIT-POLE, DARK, <External Source Name> The target DARK should be used if the pointing does not have to be constrained. If a specific pointing is desired, it should be specified on the appropriate Target List. The special target ORBIT-POLE may be used without a Target List to orient the vehicle for the maximum thermal input from the Earth. Aperture or FOV Any legal aperture from the IMAGE mode may be used. The target will be placed at this point in the FOV, as described under IMAGE mode. The guidance will be done using gyros as there are no data collected in this mode. Spectral Elements This keyword should be left blank. 189 Time Per Exposure The value is the time to be added to the minimum default value, which will determine the total time that the CCDs are at their hottest temperature. Mode = POM Configuration = WFPC2 (Restricted) The POM mode is an engineering mode which is used to adjust the on-orbit optical alignment of the WFPC2 in order to minimize coma resulting from pupil shear at the spherical aberration corrective optics. The tilt of the pick-off mirror (POM) is used to center the OTA pupil image on the secondary mirror of the relay optics for CCD WF2. The post-POM alignment of the WF2 channel is fixed and thus defines the OTA pupil to which the other channels must be aligned. POM mode exposures require that the internal target NONE be specified as well as the exposure time and Number_of_Iterations keyword. The time allocated to the mirror adjustment will be the time required for command execution and mechanism motion plus the specified exposure time. The default exposure time for POM mode exposures (specified as DEF) is zero. The Number_of_Iterations keyword will be treated as 1 regardless of the number entered. The POM mode optional parameters specify the desired mirror tilt in the WF2 detector coordinate frame relative to a nominal zero position. The mirror mechanisms will be automatically returned to their nominal zero positions at the end of every OBSET. The mirror position corresponding to the nominal zero points will be set via real-time command which will require the scheduling of an uplink opportunity during a period of WFPC2 inactivity. This is accomplished in a proposal by specifying a POM mode exposure with the Special Requirement REQ UPLINK. Because the mirror position of the proposal zero point will be changed during exposure, no optional parameters are permitted in conjunction with the REQ UPLINK Special Requirement. 190 Chapter 9: Wide Field Planetary Camera 2 (WFPC2) Optional Parameters POM-X, POM-Y (restricted) =0.0 (default); -900.0 to +900.0 arcsec Mode = AFM Configuration = WFPC2 (Restricted) The AFM mode is an engineering mode which is used to adjust the on–orbit optical alignment of the WFPC2 in order to minimize coma resulting from pupil shear at the spherical aberration corrective optics. The PC1, WF3, and WF4 optical channels have articulated fold mirrors (AFMs) which can be tilted to center the OTA pupil on the secondary mirrors of their respective relay optics. AFM mode exposures require that the internal target NONE be specified as well as the exposure time and Number_of_Iterations keyword. The time allocated to the mirror adjustment will be the time required for command execution and mechanism motion plus the specified exposure time. The default exposure time for AFM mode exposures (specified as DEF) is zero. The Number_of_Iterations keyword will be treated as 1 regardless of the number entered. The AFM mode optional parameters specify the desired mirror tilt in the appropriate detector coordinate frame (PC1, WF3 or WF4) relative to a nominal zero position. The mirror mechanisms will be automatically returned to their nominal zero positions at the end of every OBSET. The mirror positions corresponding to the nominal zero points will be set via real-time command which will require the scheduling of an uplink opportunity during a period of WFPC2 inactivity. This is accomplished in a proposal by specifying an AFM mode exposure with the Special Requirement REQ UPLINK. Because the mirror position of the proposal zero point will be changed during exposure, no optional parameters are permitted in conjunction with the REQ UPLINK Special Requirement. 191 Optional Parameters AFM1-X, AFM1-Y, AFM3-X, AFM3-Y, AFM4-X, AFM4-Y (restricted) =0.0 (default); –300.0 to +300.0 arcsec Tabular Reference Data Table 9.3: Valid WFPC2 Exposure Times (seconds)1 0.11a, b 0.20a, b 0.40b 1.00 2.00 4.00 10.00 20.00 40.00 100.00 200.00 400.00 900.00 1400.00 1900.00 2400.00 2900.00 3400.00 3900.00 4400.00 4900.00 5400.00 6200.00 7500.00 0.12a, b 0.23b 0.50b 1.20b 2.30b 5.00 12.00 23.00 50.00 120.00 230.00 500.00 1000.00 1500.00 2000.00 2500.00 3000.00 3500.00 4000.00 4500.00 5000.00 5500.00 6400.00 8000.00 0.14a, b 0.26b 0.60b 1.40b 2.60b 6.00 14.00 26.00 60.00 140.00 260.00 600.00 1100.00 1600.00 2100.00 2600.00 3100.00 3600.00 4100.00 4600.00 5100.00 5600.00 6600.00 8500.00 0.16a, b 0.30b 0.70b 1.60b 3.00 7.00 16.00 30.00 70.00 160.00 300.00 700.00 1200.00 1700.00 2200.00 2700.00 3200.00 3700.00 4200.00 4700.00 5200.00 5800.00 6800.00 9000.00 0.18a, b 0.35b 0.80b 1.80b 3.50b 8.00 18.00 35.00 80.00 180.00 350.00 800.00 1300.00 1800.00 2300.00 2800.00 3300.00 3800.00 4300.00 4800.00 5300.00 6000.00 7000.00 10000.00 a. These very short exposure times are affected by shutter movement; see the WFPC2 Instrument Handbook. b. These exposure times should not be used with CLOCKS=YES; see the WFPC2 Instrument Handbook. 1. Exposure times below the heavy line will automatically be split into two exposures unless CR-SPLIT=NO. 192 Chapter 9: Wide Field Planetary Camera 2 (WFPC2) Table 9.4: WFPC2 Supported Spectral Elements (Filters) Name Wheel Description Central Wavelengt h (Å) Effective Width (Å) F122M 1 H Ly - Alpha (Red Leak) 1420 438 F130LP 2 CaF2 Blocker (zero focus shift) 5116 4776 F160AW 1 Sodium filter A 1492 449 Note: The F160BW filter is superior to the F160AW filter. If you feel you need to use the F160AW filter, please contact your Contact Scientist. F160BW 1 Sodium filter B 1492 449 F160BN15 1 Sodium filter B rotated -15 1492 449 degrees F165LP 2 Suprasil Blocker (zero focus 5196 4541 shift) F170W 8 1750 546 F185W 8 1953 335 F218W 8 Interstellar feature 2192 388 F255W 8 2586 393 F300W 9 “Wide U” 2943 736 F336W 3 “WFPC2 U”, “Strömgren u” 3342 381 F343N 5 Ne V 3433 27 F375N 5 [O II] 3738 27 F380W 9 3964 673 F390N 5 CN 3889 45 F410M 3 “Strömgren v” 4090 147 F437N 5 [O III] 4370 25 F439W 4 “WFPC2 B” 4300 473 F450W 10 “Wide B” 4519 957 F467M 3 “Strömgren b” 4669 167 F469N 6 He II 4694 25 F487N 6 H Beta 4865 26 F502N 6 [O III] 5012 27 F547M 3 “Strömgren y” 5476 483 F555W 9 “WFPC2 V” 5398 1226 F569W 4 F555W is generally preferred 5614 966 F588N 6 He I & Na I 5894 49 F606W 10 “Wide V” 5935 1497 F622W 9 6163 917 F631N 7 [O I] 6306 31 F656N 7 H Alpha 6564 21 F658N 7 [N II] 6590 29 F673N 7 [S II] 6732 47 F675W 4 “WFPC2 R” 6696 866 193 Name Wheel Description Central Wavelengt h (Å) Effective Width (Å) F702W F785LP F791W F814W F850LP F953N F1042M 10 2 4 10 2 1 11 6868 8617 7826 7921 9072 9545 10184 1383 1332 1205 1489 986 53 365 Redshifted [O II] Redshifted [O II] rotated -33 degrees Methane Bands (Jewel Quad) Methane quad filter rotated -33 deg Methane quad filter rotated -15 deg Methane quad filter rotated +15 deg Polarizer (0, 45, 90, 135) - zero focus shift Polarizer rotated -33 degrees Polarizer rotated -18 degrees Polarizer rotated +15 degrees 3765–3992 3765 63 (avg.) 73 5433–8929 6193 49 (avg.) 44 6193 44 8929 64 Linear ramp filter set 3710–9762 1.3% CW “Wide R” F814W is generally preferred F814W is generally preferred “WFPC2 I” [S III] Quadrant Filters FQUVN FQUVN33 11 11 FQCH4N FQCH4N33 11 11 FQCH4N15 11 FQCH4P15 11 POLQ 11 POLQN33 POLQN18 POLQP15 11 11 11 Linear Ramp Filters LRF 12 Table 9.4 (cont): WFPC2 Available but Unsupported Spectral Elements (Filters) Name Wheel Description Central Wavelengt h (Å) Effective Width (Å) F160AN15 1 1492 449 F160AP15 1 1492 449 F160BP15 1 Sodium filter A rotated -15 degrees Sodium filter A rotated +15 degrees Sodium filter B rotated +15 degrees 1492 449 Linear ramp filter #1 Linear ramp filter #1 rotated -33 deg 3700–4720 3700–4720 1.3% CW 1.3% CW Linear Ramp Filters FR418N FR418N33 12 12 194 Chapter 9: Wide Field Planetary Camera 2 (WFPC2) Name Wheel Description Central Wavelengt h (Å) Effective Width (Å) FR418N18 12 3700–4720 1.3% CW FR418P15 12 3700–4720 1.3% CW FR533N FR533N33 12 12 4720–6022 4720–6022 1.3% CW 1.3% CW FR533N18 12 4720–6022 1.3% CW FR533P15 12 Linear ramp filter #1 rotated -18 deg Linear ramp filter #1 rotated +15 deg Linear ramp filter #2 Linear ramp filter #2 rotated -33 deg Linear ramp filter #2 rotated -18 deg Linear ramp filter #2 rotated +15 deg 4720–6022 1.3% CW FR680N FR680N33 12 12 6022–7683 6022–7683 1.3% CW 1.3% CW FR680N18 12 6022–7683 1.3% CW FR680P15 12 6022–7683 1.3% CW FR868N FR868N33 12 12 7683–9802 7683–9802 1.3% CW 1.3% CW FR868N18 12 Linear ramp filter #3 Linear ramp filter #3 rotated -33 deg Linear ramp filter #3 rotated -18 deg Linear ramp filter #3 rotated +15 deg Linear ramp filter #4 Linear ramp filter #4 rotated -33 deg Linear ramp filter #4 rotated -18 deg 7683–9802 1.3% CW FR868P15 12 Linear ramp filter #4 rotated +15 deg 7683–9802 1.3% CW Other filters DEF NONE Default filters No filters Table 9.5: Linked Spectral Element/Aperture Combinations for Wood’s and Quadrant Filters Spectral Element Aperture Central Wavelength (Å) Effective Width Comments (Å) F160BN15 FQUVN FQUVN FQUVN FQUVN33 F160BN15 WF2 WF3 WF4 FQUVN33 1600 3992 3913 3830 3765 900 64 59 57 73 FQCH4N FQCH4W2 5433 38 on CCD WF3 nominal rotation nominal rotation nominal rotation –33 degree rotation, on CCD WF2 nominal rotation, on CCD WF2 195 Spectral Element Aperture Central Wavelength (Å) Effective Width Comments (Å) FQCH4N FQCH4W3 8929 64 FQCH4N FQCH4W4 7274 51 FQCH4N33 FQCH4N33 6193 44 FQCH4N15 FQCH4N15 6193 44 FQCH4P15 FQCH4P15 8929 64 POLQ PC1 POLQ POLQ POLQ POLQN33 WF2 WF3 WF4 POLQN33 POLQP15 POLQP15W POLQP15 POLQP15P POLQN18 POLQN18 nominal rotation, on CCD WF3 nominal rotation, on CCD WF4 –33 degree rotation, on CCD WF2 –15 degree rotation, on CCD PC1 +15 degree rotation, on CCD PC1 pol. angle 135 degrees; POS TARG +8, +8 recommended to avoid cross-talk pol. angle 0 degrees pol. angle 45 degrees pol. angle 90 degrees pol. angle 102 degrees, on CCD WF2 pol. angle 15 degrees, on CCD WF2 pol. angle 15 degrees, on CCD PC1; not recommended: clear FOV only 3 arcsec pol. angle 117 degrees, on CCD WF2 Table 9.5 (cont): Linked Spectral Element/Aperture Combinations for Wood’s and Quadrant Filters Spectral Element Aperture Central Wavelength (Å) Effective Width Comments (Å) F160AN15 F160AN15 1600 900 on CCD WF3 WFPC2 Internal Calibration Targets (Available but Unsupported) Bias, dark, K-spot and flat field internal calibration targets are available for WFPC2. Calibration exposures are not CR-SPLIT and thus an implicit CR-SPLIT=NO is assumed. 196 Chapter 9: Wide Field Planetary Camera 2 (WFPC2) Table 9.6: Internal Calibration Targets for the WFPC2 (Available but Unsupported) Target Name Description BIAS A readout without an exposure to determine the bias level. DARK A long exposure with the shutter closed used to measure the dark count. These are treated as normal exposures, but with the shutter closed. An exposure with the Kelsall spots illuminated to register the four CCDs spatially. KSPOTS INTFLAT UVFLAT (Restricted) VISFLAT (Restricted) An internal “flat” (non–uniform) illuminated by the internal lamp reflected off the back of the shutter blades. Internal flats are generally used to monitor instrument health. An internal UV flat field calibration lamp which is reflected by a flip mirror moved into the optical path for calibrations. An internal visible flat field calibration lamp which is reflected by a flip mirror moved into the optical path for calibrations. Spectral Elements DEF (no change from previous exposure) DEF (default filters)a Time Per Exposure Zero. Enter 0S, 0M, or 0H. Enter a specific time. DEF (no change from previous exposure) Any Name from Table 9.4 DEF (default based on instrument performance), or enter a specific time. DEF (default based on instrument performance), or enter a specific time. Any Name from Table 9.4 DEF (default based on instrument performance), or enter a specific time. Any Name from Table 9.4 DEF (default based on instrument performance), or enter a specific time. a. If the DARK target is used with DECON mode, the spectral element should be left blank as specified in “Mode = DECON Configuration = WFPC2 (Restricted)” on page 188. 197 WFPC2 Aperture Coordinate System Figure 9.1: WFPC2 Aperture Coordinate System +U2 (-V2) +U3 (-V3) Y X 45.28˚ PA_V3 N E WF2 PC COSTAR WF3 WF4 To the sun 1 arcminute Coordinate system is onto the sky for the POSition TARGet Special Requirement. The short lines indicate the blooming directions of the CCDs. Units are seconds of arc. See POSition TARGet <X-value>, <Y-value> for details. Note that the POS TARG X– and Y–axes are not the same as the U2– and U3–axes, and that POS TARG axes are associated with each aperture selected (i.e., there is a POS TARG coordinate frame centered on each aperture). 198 Chapter 9: Wide Field Planetary Camera 2 (WFPC2) CHAPTER 10: Space Telescope Imaging Spectrograph (STIS) For an explanation of this engineering-only version, see Special Note to Engineering Version Users in Chapter 1: About This Document on page 3. In this chapter . . . Introduction to STIS / 200 ACQUISITION MODES / 202 Mode = ACQ Configuration = STIS/CCD / 203 Mode = ACQ/PEAK Config = STIS/CCD / 206 IMAGING AND SPECTROSCOPIC MODES / 210 Mode = ACCUM Config = STIS/CCD / 210 Mode = ACCUM Config = STIS/FUV–MAMA, Config = STIS/NUV–MAMA / 215 Mode = TIME–TAG Configuration = STIS/FUV–MAMA, Configuration = STIS/NUV–MAMA / 218 SUPPORT MODES (Restricted) / 221 Mode = ALIGN (Restricted) Configuration = STIS (Restricted) / 221 Mode = ANNEAL (Restricted) Configuration = STIS (Restricted) / 223 Mode = MSMOFF (Restricted) Configuration = STIS (Restricted) / 224 REFERENCE INFORMATION / 226 STIS Central Wavelengths / 226 STIS Internal Calibration Targets / 227 Target_Name = WAVE / 227 Target_Name = CCDFLAT / 229 Target_Name = BIAS (Restricted) / 231 Target_Name = DARK (Restricted) / 231 STIS Coordinate System / 232 The Official STIS Aperture List for Cycle 10 / 234 199 200 Chapter 10: Space Telescope Imaging Spectrograph (STIS) Tables and Figures Table 10.1: Supported Optional Parameters for STIS Instrument Modes Table 10.1 (cont): Available but Unsupported and Restricted STIS Parameters Table 10.2: Supported Central Wavelengths for STIS Gratings Table 10.2 (cont): Available but Unsupported Wavelengths for STIS Gratings Table 10.2 (cont): Wavelengths for Restricted Gratings Table 10.3: Time_Factor for Spectral Elements and Wavelenghts. Table 10.4: Supported STIS Apertures Table 10.4 (cont): Available-but-Unsupported and Restricted STIS Apertures Figure 10.1 STIS coordinate system (shown projected onto the sky, as used with the POS TARG Special Requirement). Introduction to STIS The Instrument Configurations and Operating Modes described here are used to specify exposures on the RPS2 Visit and Exposure Specifications. The legal Visit and Exposure Specifications are discussed in a summary fashion in the following sections. More complete descriptions of Instrument Configurations, Modes, Apertures, Spectral Elements, etc. are available in the STIS Instrument Handbook. Note that many of the Optional Parameters have default values; in such cases, an entry as an Optional Parameter in the Visit and Exposure Specifications is necessary only if it is desired to override the default value. In the STScI proposal system, the physical units of Optional Parameter quantities are always implicit and should never be entered by the observer. STIS has a lot of apertures, and keeping track of them is difficult. To simplify matters somewhat, and to avoid typographical errors, a complete list of them is provided at the end of this chapter (see Table 10.4: Supported STIS Apertures). That table should be taken as definitive if any additional information in this chapter appears to conflict. The following table lists the permitted Instrument Configurations, Operating Modes, Spectral Elements, and Optional Parameters for the STIS. 201 Note also that in addition to the automatic wavelength calibrations added by the system, the following observer-added contemporaneous calibrations may also be made: • CCDFLAT (fringe flats) for G750L and G750M observations longward of 7000 Å. • WAVE calibrations for added wavelength precision. See the STIS Instrument Handbook for more information. Some STIS modes will work without an initial ACQuisition (such as slitless spectroscopy and imaging), but in general the user must ensure that ACQuisitions are included where needed. An ACQ/PEAK should always be preceded by an ACQuisition. Table 10.1: Supported Optional Parameters for STIS Instrument Modes Config. Mode Spectral Elements Optional Parameters STIS/CCD ACQ MIRROR ACQTYPE, DIFFUSE–CENTER, CHECKBOX ACQ/PEAK MIRROR, G230LB, G230MB, G430L, G430M, G750L, G750M SIZEAXIS2 MIRROR, G140L, G140M, E140M, E140H BINAXIS1, BINAXIS2 MIRROR, G230L, G230M, E230M, E230H, PRISM BINAXIS1, BINAXIS2 ACCUM STIS/FUV– MAMA STIS/NUV– MAMA ACCUM TIME–TAG ACCUM TIME–TAG CR–SPLIT, GAIN, BINAXIS1, BINAXIS2, SIZEAXIS2 BUFFER–TIME BUFFER–TIME Table 10.1 (cont): Available but Unsupported and Restricted STIS Parameters Spectral Elements Configuration Mode Optional Parameters STIS/CCD ACQ GAIN ACQ/PEAK SIZEAXIS1, CENTERAXIS2, CENTERAXIS1, SEARCH, NUM–POS, STEP–SIZE, CENTROID, GAIN ACCUM SIZEAXIS1, CENTERAXIS2, CENTERAXIS1, WAVECAL, PREFLUSH 202 Chapter 10: Space Telescope Imaging Spectrograph (STIS) Spectral Elements Configuration Mode Optional Parameters STIS/CCD ACCUM LAMP (Restricted), SLIT–STEP (Restricted) AMP (Restricted) STIS/FUV– MAMA ACCUM, TIME–TAG WAVECAL, SLIT–STEP (Restricted), LAMP (Restricted) STIS/NUV– MAMA ACCUM, TIME–TAG WAVECAL, SLIT–STEP (Restricted), LAMP (Restricted) STIS/FUV–MA MA, STIS/NUV–M AMA ACCUM X140H, X140M, X230H, X230M LAMP (Restricted), SLIT–STEP (Restricted) STIS (Restricted) ALIGN (Restricted) DEF FOCUS (Restricted), XTILT (Restricted), YTILT (Restricted) ANNEAL (Restricted) MSMOFF (Restricted) SETOFFSET (Restricted), GRATING1 (Restricted), GRATING2 (Restricted), GRATING3 (Restricted), WAVELENGTH (Restricted) The following sections provide further details of the entries to be made on the Visit and Exposure Specifications when a particular STIS/CCD, STIS/FUV–MAMA, or STIS/NUV–MAMA or STIS (Restricted) Mode/Configuration is chosen. Note: the AXIS1 and AXIS2 coordinate system is as defined in the discussion of the STIS coordinate system, which is in the STIS Instrument Handbook. Array sizes are given as AXIS1 x AXIS2. For CCD and MAMA first-order grating and MAMA echelle spectroscopic modes, AXIS1 is in the dispersion direction and AXIS2 is in the cross-dispersion direction. For the (Restricted) MAMA cross-disperser modes (X140H, X140M, X230H, X230M), this interpretation is reversed: AXIS1 corresponds to the cross-dispersion direction, and AXIS2 to the dispersion direction. ACQUISITION MODES Following the initial guide star acquisition for your visit, the target location in the aperture plane will be known to an accuracy of 1–2 arcseconds. For science observations taken through slits which are less than 3 arcseconds in 203 either dimension and for science observations using the coronographic bars, you will need to use target acquisition (ACQ Mode) and possibly acquisition peak-up exposures (ACQ/PEAK Mode) to center your target. The CCD detector may be used for acquisitions of targets which will be observed in the CCD and MAMA ACCUM Modes and in the MAMA TIME-TAG Mode. Details on the STIS target acquisition modes are in the STIS Instrument Handbook The STIS Target Acquisition Exposure Time Calculator (ETC) and Target Acquisition Simulator are tools provided by STScI to help plan acquisitions. Look under “Tools” on the STIS web page: http://www.stsci.edu/stis Mode = ACQ Configuration = STIS/CCD The STIS onboard flight software locates the target in the STIS FOV for subsequent science exposures. At the end of the onboard acquisition process, the HST is repositioned to place the target in the aperture specified on the first science exposure in the series. Onboard acquisitions of two different types of targets are supported: point sources and diffuse fields. The total flux within a sequence of overlapping “check boxes” within an acquisition subarray is determined, and the target position is located within the brightest check box. The visual magnitude from the Target List, along with the exposure time, will be used to verify that the integrated target flux through the selected acquisition aperture is appropriate for CCD target acquisition. Details on the CCD target acquisition sequence and limiting magnitudes for the acquisition apertures and spectroscopic slits can be found in the STIS Instrument Handbook. Aperture or FOV See Table 10.1: Supported Optional Parameters for STIS Instrument Modes and Table 10.4: Supported STIS Apertures. 204 Chapter 10: Space Telescope Imaging Spectrograph (STIS) Enter one of the following apertures: Entry Description F28X50LP Optical longpass; preferred target acquisition aperture F28X50OII [OII] 3740 Å; use for bright sources or emission-line objects F28X50OIII [OIII] 5007 Å; use for bright sources or emission-line objectsa F25ND3 Neutral density filter for overly bright targets; ND = ~10^–3 F25ND5 Neutral density filter for overly bright targets; ND = ~10^–5 50CCD Clear aperture for very faint sources a. Please note that this filter has a substantial red leak; see the STIS Instrument Handbook. Spectral Element MIRROR is the only valid spectral element for this Mode. Optional Parameters See Table 10.1: Supported Optional Parameters for STIS Instrument Modes for a listing by operating mode of all Optional Parameters. Here are descriptions for those Optional Parameters for ACQ mode. ACQTYPE =POINT (default), DIFFUSE Specifies the type of onboard target acquisition algorithm used in locating the target. Onboard algorithms are available for acquiring a point source or a diffuse field. With the default value of POINT, an acquisition subarray of 100 x 100 CCD pixels (5x5 arcsec) and a check box of 3x3 CCD pixels is always used. The target position is the flux-weighted centroid of the brightest check box within the subarray. With the DIFFUSE acquisition type, the acquisition subarray is a square array. The number of pixels on each side is 101 + CHECKBOX (see below). The target position is either the geometric center or the flux-weighted centroid of the brightest check box, depending on the DIFFUSE–CENTER parameter. DIFFUSE–CENTER =FLUX–CENTROID (default), GEOMETRIC–CENTER 205 Specifies whether the target position of a diffuse field is to be located as the flux weighted centroid (FLUX–CENTROID) or the geometric center (GEOMETRIC–CENTER) of the brightest check box. DIFFUSE– CENTER is only permitted if ACQTYPE=DIFFUSE. CHECKBOX =3–105 (pixels; odd only) Specifies the length of a side of a square pixel array over which the light intensity is summed to locate the brightest region of the acquisition. This parameter is required for diffuse targets (ACQTYPE=DIFFUSE). It is not allowed for point sources (ACQTYPE=POINT), for which a fixed checkbox size based on the PSF will be used. The value of CHECKBOX should equal the size of the brightest area of the source the observation is attempting to locate. The dimension of the acquisition subarray will be 101 pixels plus the CHECKBOX parameter. The value of CHECKBOX must be an odd number. GAIN (Available but Unsupported) =4 (default), 1, 2, 8 (e/DN) Specifies the gain of the CCD electronics in e/DN. Number of Iterations The Number_Of_Iterations must be 1 in this Mode. Time Per Exposure The procedures to determine the exposure time for the ACQ exposures are given in the STIS Instrument Handbook. The exposure time for ACQ exposures on GO proposals must be less than 5 minutes for ACQTYPE=POINT acquisitions, and for ACQTYPE=DIFFUSE acquisitions must be less than 500/(101+CHECKBOX) minutes. Special Requirements None. 206 Chapter 10: Space Telescope Imaging Spectrograph (STIS) Mode = ACQ/PEAK Config = STIS/CCD In ACQ/PEAK Mode, a series of exposures is taken at several HST pointings offset along the detector axes, and the HST is repositioned to maximize (peak up) or minimize (peak down) the light intensity within a default or proposer-specified detector subarray. AXIS1 and AXIS2 are in the dispersion and cross-dispersion directions, respectively. For more information, including when peak-ups are required, see the STIS Instrument Handbook. Mode ACQ/PEAK should always be preceded by an ACQuisition. Aperture or FOV The aperture used for the ACQ/PEAK exposure will generally be identical to the aperture used for the subsequent ACCUM science exposure. For maximum centering accuracy, a peakup aperture smaller than the science exposure may be chosen. The apertures in Table 10.4: Supported STIS Apertures are allowed. A peak-down on the target intensity will automatically be performed on the occulting bar apertures 52X0.2F1. A peak-down on the target intensity will automatically be performed for SEARCH= LINEARAXIS2 (spatial) scans on occulting bar apertures 52X0.05F1, 52X0.05F2, 52X0.1B0.5, 52X0.1B1.0, 52X0.1B3.0, 52X0.1F1, 52X0.1F2, 52X0.2F2, 52X0.5F1, 52X0.5F2, 52X2F1, 52X2F2, BAR10, WEDGEA1.0, WEDGEA1.8, WEDGEA2.0, WEDGEA2.5, WEDGEA2.8, WEDGEB1.0, WEDGEB1.8, WEDGEB2.0, WEDGEB2.5, WEDGEB2.8. A peak-up will be performed otherwise. To peak up on the width of a slit with an occulting bar before peaking down on the bar itself, the occulting bar aperture name with –R appended to it should be used. Such exposures will peak up on a reference point offset from the occulting bar along the slit’s length. Spectral Element See Table 10.1: Supported Optional Parameters for STIS Instrument Modes. 207 Optional Parameters See Table 10.1: Supported Optional Parameters for STIS Instrument Modes for a listing by operating mode of all Optional Parameters. Here are descriptions for those Optional Parameters for ACQ/PEAK mode. SIZEAXIS2 =DEF (default); 30–1022 (pixels, dispersive elements), 16–1022 (pixels, MIRROR) Specifies the size of a CCD subarray in detector coordinates along the AXIS2 (cross-dispersion) direction. The default subarray with SIZEAXIS2=DEF depends on the aperture and spectral element. With the MIRROR element, the default subarray will generally be 32x32 CCD pixels centered on the aperture. However, the F1 fiducial slits use a 32x64 subarray. A subarray of 16x16 is also allowed when MIRROR is used. The F2 fiducial slits use a 32 x 128 subarray, and the planetary slits (36X0.05P45, 36X0.05N45, 36X0.6P45, 36X0.6N45) use a 64 x 32 subarray. With a first-order CCD grating (G230LB, G230MB, G430L, G430M, G750L, G750M), the default subarray will generally be 1022 x 32 CCD pixels. However, the F1 fiducial slits use a 1022 x 64 subarray. The F2 fiducial slits use a 1022 x 128 subarray. These subarrays have been chosen to minimize cosmic ray perturbations on the acquisition process. The SIZEAXIS2, SIZEAXIS1, SEARCH, NUM–POS, and STEP–SIZE parameters are required with the following apertures: BAR10, WEDGEA1.0, WEDGEA1.8, WEDGEA2.0, WEDGEA2.5, WEDGEA2.8, WEDGEB1.0, WEDGEB1.8, WEDGEB2.0, WEDGEB2.5, WEDGEB2.8, 0.5X0.5, 6X0.5, 52X0.1B0.5, 52X0.1B1.0, 52X0.1B3.0, 52X0.5, 52X0.5F1, 52X0.5F1–R, 52X0.5F2, 52X0.5F2–R, 52X2, 52X2F1, 52X2F1–R, 52X2F2, and 52X2F2–R. SIZEAXIS1 (Available but Unsupported) =DEF (default); 30–1060 (pixels, dispersive elements), 16–1060 (pixels, MIRROR) Specifies the size of a CCD subarray in detector coordinates along the AXIS1 (dispersion) direction. The default subarray with SIZEAXIS1=DEF depends on the aperture and spectral element, as given under SIZEAXIS2 above. 208 Chapter 10: Space Telescope Imaging Spectrograph (STIS) CENTERAXIS2 (Available but Unsupported) =TARGET (default); 17–1009 (pixels, dispersive elements), 10–1016 (pixels, MIRROR) Specifies the center of a CCD subarray in detector coordinates along the AXIS2 (cross-dispersion) direction. The default value of TARGET means that the subarray will be centered on the detector coordinates of the target (which change with POSition TARGet offsets). CENTERAXIS1 (Available but Unsupported) =TARGET (default); 17–1047 (pixels, dispersive elements), 10–1054 (pixels, MIRROR) Specifies the center of a CCD subarray in detector coordinates along the AXIS1 (dispersion) direction. The default value of TARGET means that the subarray will be centered on the detector coordinates of the target. SEARCH (Available but Unsupported) =DEF (default), SPIRAL, LINEARAXIS1, LINEARAXIS2 Specifies whether an ACQ/PEAK exposure should consist of a SPIRAL, LINEARAXIS1, or LINEARAXIS2 scan of vehicle positions (in detector coordinates) to peak up or peak down the light intensity through a spectroscopic slit. The default value will be based on the slit and scan type requested for the exposure. See the STIS Instrument Handbook for default values. If any of the parameters SEARCH, NUM–POS, or STEP–SIZE have non-default values, then all three parameters must have non-default values NUM–POS (Available but Unsupported) =DEF (default); 3–49 (pixels; odd only) Specifies the number of dwell positions (including the initial target position) in an ACQ/PEAK scan. The default value will be based on the slit and scan type requested for the exposure; see the STIS Instrument Handbook for default values. Only odd numeric values are allowed. If SEARCH=SPIRAL, the value of NUM–POS must be 9, 25, or 49. STEP–SIZE (Available but Unsupported) =DEF (default); 1–1000 (milliarcsec) 209 Specifies the size in milli-arcseconds of each vehicle step in a centering scan. The default value will be based on the slit and scan type requested for the exposure. See the STIS Instrument Handbook for default values. CENTROID (Available but Unsupported) =YES (default), NO Specifies the algorithm to center the target. If CENTROID=YES, the flight software uses a flux-weighted centroiding technique to determine the optimum position. If CENTROID=NO, the brightest dwell point will be used for the optimum position. A peak-down will automatically be performed if the selected aperture (see Table 10.4: Supported STIS Apertures) contains an occulting bar or wedge. For all other apertures, a peak-up is performed. The occulting-bar apertures are those listed in the paragraph at the end of the “Aperture or FOV” section above. GAIN (Available but Unsupported) =4 (default); 1, 2, 8 (e/DN) Specifies the gain of the CCD electronics in e/DN. Number of Iterations The Number_Of_Iterations must be 1 in this Mode. Time Per Exposure The procedures to determine the exposure time for the ACQ/PEAK exposure are given in the STIS Instrument Handbook. Special Requirements None. 210 Chapter 10: Space Telescope Imaging Spectrograph (STIS) IMAGING AND SPECTROSCOPIC MODES Mode = ACCUM Config = STIS/CCD The STIS CCD has only one operating mode in addition to the target acquisition modes, ACCUM. ACCUM Mode is used both for imaging and spectroscopy. Photons are counted on the CCD as accumulated charge which is read out at the end of the exposure and converted to DN at a selectable gain. The DN are stored as 16-bit words in a data memory array. A full detector readout is 1062 x 1044 pixels, which includes 19 leading pixels and 19 trailing pixels of overscan per line and 20 virtual overscan lines. A CCD subarray does not include the virtual overscan or any of the physical pixels bordering the outer edges of the array, so that the maximum permitted subarray size is 1060 x 1022 pixels. Aperture or FOV Table 10.4: Supported STIS Apertures gives the list of apertures for STIS. Spectral Element See Table 10.1: Supported Optional Parameters for STIS Instrument Modes. Wavelength Enter the value of the central wavelength in Angstroms. Table 10.2 gives the allowed values of the central wavelength for each grating. Consult the STIS Instrument Handbook for the associated minimum and maximum wavelength and other information pertaining to the gratings. No wavelength should be specified if MIRROR is the spectral element 211 Optional Parameters See Table 10.1: Supported Optional Parameters for STIS Instrument Modesfor a listing by operating mode of all Optional Parameters. Here are descriptions for those Optional Parameters for the imaging and spectroscopic modes. CR–SPLIT = 2 (default) – 8; NO (primary and coordinated parallel exposures) = NO (pure parallel exposures) Specifies the number of subexposures into which the specified exposure is to be split for the purpose of cosmic ray elimination in post-observation data processing (see the STIS Instrument Handbook). The specified exposure time will be divided equally among the number of CR–SPLIT exposures requested. If CR–SPLIT=NO, the exposure is taken as specified without splitting. If a pattern of offsets is specified (see Chapter 8: Pointings and Patterns), the specified number of exposures will be taken at each pattern point. CR-SPLIT=NO must always be used with pure parallel exposures in this mode. If omitted, the default value of CR-SPLIT for pure parallels is NO. CR-SPLIT=NO is always assumed for internal exposures. If explicitly stated, the only permitted value for internals is CR-SPLIT=NO. GAIN =1 (default), 4, 2, 8 (e/DN) Specifies the gain of the CCD electronics in e/DN. BINAXIS1, BINAXIS2 =1 (default), 2, 4 (pixels) for either Specifies the number of CCD pixels along the AXIS1 or dispersion (BINAXIS1) and AXIS2 or cross-dispersion (BINAXIS2) directions that are binned to a single signal value as the detector is read out. The default values result in each pixel being read out and downlinked to the ground. See the discussion of binning in the STIS Instrument Handbook. BINAXIS1 and BINAXIS2 are not permitted in conjunction with CCD subarray parameter SIZEAXIS2. BINAXIS1 and BINAXIS2 are not permitted in conjunction with CCD subarray parameters SIZEAXIS1, CENTERAXIS2, and CENTERAXIS1. 212 Chapter 10: Space Telescope Imaging Spectrograph (STIS) SIZEAXIS2 =FULL (default); 30–1022 (pixels) Specifies the size of a CCD subarray in detector coordinates along the AXIS2 (cross-dispersion) direction. The default value of FULL for science exposures will result in the readout of a full detector array of 1044 pixels (including virtual overscan) in the AXIS2 direction. The default value of FULL means that the subarray will be centered on the detector coordinates of the target (which change with POSition TARGet offsets). SIZEAXIS1 (Available but Unsupported) =FULL (default); 30–1060 (pixels) Specifies the size of a CCD subarray in detector coordinates along the AXIS1 (dispersion) direction. The default value of FULL for science exposures will result in the readout of a full detector array of 1062 pixels (including physical overscan) in the AXIS1 direction. CENTERAXIS2 (Available but Unsupported) =TARGET (default); 17–1009 (pixels) Specifies the center of a CCD subarray in detector coordinates along the AXIS2 (cross-dispersion) direction. The default value of TARGET means that the subarray will be centered on the detector coordinates of the target (which change with POSition TARGet offsets). CENTERAXIS1 (Available but Unsupported) =TARGET (default); 17–1047 (pixels) Specifies the center of a CCD subarray in detector coordinates along the AXIS1 (dispersion) direction. The default value of TARGET means that the subarray will be centered on the detector coordinates of the target. WAVECAL (Available but Unsupported) =YES (default), NO Controls the automatic scheduling of wavelength calibration exposures for external spectroscopic science exposures. A value of WAVECAL=NO will disable automatic wavelength calibrations for the entire visit. WAVECAL should only be specified once per visit. PREFLUSH (Available but Unsupported) =NO (default), YES 213 Requests a one-hour flush of the CCD before taking the CCD ACCUM exposure on which it is specified. Note that PREFLUSH can be scheduled during SAA passage. LAMP (Available but Unsupported) =TUNGSTEN Identifies the internal STIS calibration lamp TUNGSTEN to be used for a calibration exposure. Exposures using LAMP will be scheduled as internal, non-pointed exposures and must have the target name NONE. LAMP (Restricted) =HITM1, HITM2, LINE, DEUTERIUM (no default) RESTRICTED—Identifies the internal STIS calibration lamp to be used for a calibration exposure. Exposures using LAMP will be scheduled as internal, non-pointed exposures and must have the target name NONE. If LAMP=HITM1, HITM2, LINE, or DEUTERIUM, exposure times greater than 1000 seconds should be used with care to avoid overuse of the line lamps. SLIT–STEP (Restricted) =0 (default); –31000 to 31000 (steps) RESTRICTED—This parameter is only allowed with LAMP values of TUNGSTEN or DEUTERIUM. It allows the slit projection on the detector to be offset from the default position. SLIT–STEP is given in slit wheel resolver steps (70 per CCD pixel). Within the range of –10000 to 10000 steps, the field of view remains within the chosen aperture. For optimum flat fielding, it is necessary to break up the full flat-field integration time into multiple (3–5) exposures, and slightly offset the slit projection on the detector from exposure to exposure. This allows smoothing out of the physical inhomogeneities along the slit surfaces and allows flats to be obtained under the fiducial bars. Note that adding the SLIT-STEP Optional Parameter causes the aperture wheel to be moved by the indicated offset, but only if the aperture wheel is moved on the current exposure line. Specifying SLIT-STEP alone does not cause such a movement of the aperture wheel. The aperture wheel moves whenever the currently specified aperture differs from that of the previous exposure line. If the aperture is not changed, SLIT-STEP has no effect. 214 Chapter 10: Space Telescope Imaging Spectrograph (STIS) AMP (Restricted) = A, B, C, D (no default) RESTRICTED—Use this parameter to specify a particular CCD readout amplifier to be used for the logsheet line. Optional Parameter AMP should not be used with WAVE or CCDFLAT internal calibration targets. Number of Iterations and Time Per Exposure Enter the number of times this exposure should be iterated. For instance, specifying 10 iterations and a Time_Per_Exposure of 10 seconds will give a total exposure time of 100 seconds. There are many observational situations when two or more exposures should be taken of the same field (e.g., to keep a bright object from blooming by keeping the exposure time short). The value entered for the Time_Per_Exposure is the total exposure time for a particular exposure specification. If the Number_Of_Iterations is n, the entire exposure specification will be iterated n times. However, if CR–SPLIT is used, the total exposure time will actually be apportioned among shorter exposures: specifying an exposure time of 10 seconds and CR–SPLIT=2 results in two exposures of 5 seconds each. If Number_Of_Iterations > 1 is specified with a pattern, the pattern is executed once with the specified number of iterations being taken at each point in the pattern. If no pattern is specified, the specified number of iterations will be taken at the single pointing. Number_Of_Iterations must be 1 for STIS pure parallels (except for CCDFLAT; see Target_Name = CCDFLAT on page 229). CR–SPLIT and multiple iterations are mutually exclusive capabilities. If Number_Of_Iterations > 1 on an external exposure, CR–SPLIT=NO must be specified. Time_Per_Exposure must be an integral multiple of 0.1 second. If it is not its value will be truncated down to the next lower integral multiple of 0.1 sec. If the exposure time is less than 0.1 sec, it will be set to the CCD minimum value of 0.1 sec. An exposure time of less than 0.1 sec will be set to the minimum CCD exposure time of 0.1 second. 215 Mode = ACCUM Config = STIS/FUV–MAMA, Config = STIS/NUV–MAMA The two MAMAs are photon-counting detectors which provide a two-dimensional ultraviolet capability. ACCUM Mode should be used for all observations that do not require time resolution on scales of minutes or less. Dispersion (in spectroscopic modes) runs along AXIS1, and the cross-dispersion or spatial direction of the slit is along AXIS2. There are 1024 x 1024 physical pixels in the MAMA array, but each physical pixel is sampled by three electrodes, allowing centroiding of photons to half-pixel accuracy. In ACCUM Mode, the MAMAs accumulate photons in the STIS data buffer as they are received, producing images with 2048 x 2048 “high-resolution” pixels with half physical pixel coordinates. Images can be binned either by the STIS flight software (using the BINAXIS1 and BINAXIS2 optional parameters described below) or on the ground, to produce images with 1024 x 1024 physical pixels. All optional parameters are specified in physical pixel coordinates. For a more detailed description, see the discussion of MAMA ACCUM mode in the STIS Instrument Handbook. Subarrays may not be used with the MAMA detectors. Aperture or FOV Table 10.4: Supported STIS Apertures gives the list of apertures that are Supported for STIS use. For the restricted gratings X140H, X140M, X230H, and X230M, the following apertures may be used: 0.05X29, 0.05X31NDA, 0.05X31NDB, 0.09X29, 0.2X29. Supported Spectral Elements See Table 10.1: Supported Optional Parameters for STIS Instrument Modes. 216 Chapter 10: Space Telescope Imaging Spectrograph (STIS) Wavelength Enter the value of the central wavelength in Angstroms. Table 10.2 gives the allowed values of the central wavelength for each spectroscopic spectral element. Consult the STIS Instrument Handbook for the associated minimum and maximum wavelength and other information pertaining to the spectroscopic elements. No wavelength should be specified if the MIRROR is the spectral element. Optional Parameters See Table 10.1: Supported Optional Parameters for STIS Instrument Modes for a listing by operating mode of all Optional Parameters. Here are descriptions for those Optional Parameters for MAMA ACCUM mode. BINAXIS1, BINAXIS2 =DEF (default), NO, YES (for either) These parameters specify whether onboard rebinning is to be performed on the accumulated image in memory after the exposure is completed. MAMA photon events are stored in memory in half-pixel coordinates (high-resolution pixels). The rebinning process is a summation of two high-resolution pixels in the AXIS1 or dispersion (BINAXIS1) and/or AXIS2 or cross-dispersion (BINAXIS2) detector directions to values corresponding to the physical pixels of the detector. The default values for all spectral elements and apertures are not to rebin in either direction, resulting in four high-resolution pixel values for each physical pixel. When used with the MAMA detectors, BINAXIS1 and BINAXIS2 must have the same value! For the Restricted spectral elements X140H, X140M, X230H, and X230M, the normal interpretation of AXIS1 and AXIS2 is reversed: AXIS1 corresponds to the cross-dispersion or spatial direction, and AXIS2 to the dispersion direction. 217 WAVECAL (Available but Unsupported) =YES (default), NO Controls the automatic scheduling of wavelength calibration exposures for external spectroscopic science exposures. A value of WAVECAL=NO will disable automatic wavelength calibrations for the entire visit. WAVECAL should only be specified once per visit. LAMP (Restricted) =HITM1, HITM2, LINE, DEUTERIUM, KRYPTON (no default) Restricted—Identifies the internal STIS calibration lamp to be used for a calibration exposure. Exposures using LAMP will be scheduled as internal, non-pointed exposures and must have the target name NONE. If LAMP=HITM1, HITM2,DEUTERIUM, KRYPTON, or LINE, exposure times greater than 1000 seconds should be used with care to avoid overuse of the line lamps. For LAMP=HITM1, HITM2, KRYPTON, DEUTERIUM, or LINE, there are additional restrictions for the MAMAs on the legal combinations of apertures, spectral elements, and central wavelengths beyond those given in the tables. Consult the STIS instrument group. SLIT–STEP (Restricted) =0 (default); –10000 to 10000 (steps) Restricted—This parameter is only allowed with LAMP values of DEUTERIUM or KRYPTON. It allows the slit projection on the detector to be offset from the default position. SLIT–STEP is given in slit wheel resolver steps (35 per MAMA pixel). Within the legal range of –10000 to 10000 steps, the field of view remains within the chosen aperture. For optimum flat fielding, it is necessary to break up the full flat-field integration time into multiple (3–5) exposures, and slightly offset the slit projection on the detector from exposure to exposure. This allows smoothing out of the physical inhomogeneities along the slit surfaces and allows flats to be obtained under the fiducial bars. Note that adding the SLIT-STEP Optional Parameter causes the aperture wheel to be moved by the indicated offset, but only if the aperture wheel is moved on the current exposure line. Specifying SLIT-STEP alone does not cause such a movement of the aperture wheel. The aperture wheel moves whenever the currently specified aperture differs from that of the previous exposure line. If the aperture is not changed, SLIT-STEP has no effect. 218 Chapter 10: Space Telescope Imaging Spectrograph (STIS) Number of Iterations and Time Per Exposure Enter the number of times (Number_Of_Iterations) this exposure should be iterated, and the exposure time (Time_Per_Exposure) per iteration. If Number_Of_Iterations > 1 is specified with a pattern, the pattern is executed once with the specified number of iterations being taken at each point in the pattern. If no pattern is specified, the specified number of iterations will be taken at the single pointing. Time_Per_Exposure must be an integral multiple of 0.1 second. If it is not its value will be truncated down to the next lower integral multiple of 0.1 sec. If the exposure time is less than 0.1 sec, it will be set to the MAMA minimum value of 0.l sec. Mode = TIME–TAG Configuration = STIS/FUV–MAMA, Configuration = STIS/NUV–MAMA TIME–TAG Mode is used for imaging and spectroscopy with high time resolution. When used in TIME–TAG Mode, the MAMA produces an event stream with a time resolution of 125 microseconds. If the incoming event rate exceeds about 770,000 counts per second, not all events get registered due to finite electronic response time. The AXIS1 and AXIS2 half-pixel coordinates (11 bits each) of each photon event, along with 9 bits of fine-resolution time data, are stored as a 32-bit word in data buffer memory. See the discussion of TIME–TAG Mode in the STIS Instrument Handbook. Aperture or FOV Table 10.4: Supported STIS Apertures gives the list of apertures that are Supported for STIS use. For the restricted gratings X140H, X140M, X230H, and X230M, the following apertures may be used: 0.05X29, 0.05X31NDA, 0.05X31NDB, 0.09X29, 0.2X29. Spectral Element See Table 10.1: Supported Optional Parameters for STIS Instrument Modes. 219 Wavelength Enter the value of the central wavelength in Angstroms. Table 10.2 gives the allowed values of the central wavelength for each spectroscopic spectral element. Consult the STIS Instrument Handbook for the associated minimum and maximum wavelength and other information pertaining to the spectroscopic elements. No wavelength should be specified if the MIRROR is the spectral element. Optional Parameters See Table 10.1: Supported Optional Parameters for STIS Instrument Modes for a listing by operating mode of all Optional Parameters. Here are descriptions for those Optional Parameters for MAMA TIME-TAG mode. BUFFER– TIME =40 or greater (integer seconds) A required parameter which specifies the estimated minimum time in which 2 x 10^6 photon events (half of the STIS data buffer capacity) will be accumulated during a TIME–TAG exposure. If the predicted total number of events from a TIME–TAG exposure exceeds the STIS data buffer capacity of 4 x 10^6 photon events, data must be transferred to the HST onboard science data recorder during the exposure. Transfers of data from the STIS buffer during an exposure will be made in 8-MByte blocks (half the buffer capacity). The value of BUFFER–TIME should be the half-buffer capacity (2 x 10^6 counts) divided by the estimated maximum average count rate in photons per second (see the STIS Instrument Handbook). If the actual count rate is less than expected and fewer than 2 x 10^6 counts are received during this time, the 8-MByte blocks will contain fill data. Note that BUFFER–TIME should include expected counts from the detector dark current as well as the detected photon events, factoring in the instrument quantum efficiency. A conservative value of BUFFER–TIME is recommended (err slightly on the low side) to avoid data loss. For more details, see the STIS Instrument Handbook. 220 Chapter 10: Space Telescope Imaging Spectrograph (STIS) WAVECAL (Available but Unsupported) =YES (default), NO This is the same as in ACCUM Mode; see “WAVECAL (Available but Unsupported)” on page 212 Number of Iterations and Time Per Exposure Number_Of_Iterations must be 1 in this mode. Time_Per_Exposure must be an integral multiple of 0.1 second. If it is not its value will be truncated down to the next lower integral multiple of 0.1 sec. Enter the total time of data collection as Time_Per_Exposure. An exposure time of less than 0.1 sec will be set to the minimum MAMA exposure time of 0.1 second. If BUFFER–TIME < 99 seconds, photon events will be generated faster than data can be transferred out of the buffer during the exposure. In this case, Time_Per_Exposure should be less than or equal to 2 * BUFFER–TIME so that the exposure can complete before data transfer is necessary. A BUFFER–TIME of 99 seconds corresponds to a maximum average count rate of 20,200 counts/sec. Note that TIME–TAG exposures have the potential to rapidly use up the HST onboard storage capacity. Caution is advised on any exposure with an exposure time greater than 30 * BUFFER–TIME, which corresponds to 6 x 10^7 counts, or about 2 GBits (close to 20% of the solid-state recorder capacity). Please see the STIS Instrument Handbook. Special Requirements The special requirements RT ANALYSIS and PARallel WITH are not permitted on TIME–TAG Mode exposures. 221 SUPPORT MODES (Restricted) Mode = ALIGN (Restricted) Configuration = STIS (Restricted) Restricted—This Mode is used to move the STIS internal focus and tilt mechanisms via stored commanding for the purpose of on-orbit alignment of the aberration correction optics. ALIGN exposures do not acquire science data and must be interleaved with science mode exposures to obtain data, with the alignment mechanisms at a variety of positions for the ground alignment process. The values of the Optional Parameters specify the positions of the three alignment mechanisms in motor steps, relative to a nominal zero position. The mechanism positions at nominal zero will be set via real-time command, which allows a preplanned scan of a mechanism’s position to be specified without knowledge of where in the mechanism range the scan will be executed. Since the absolute positions are set in real time, a check that the preplanned scans about the nominal zero positions do not violate the mechanism range limits cannot be performed by the scheduling system. The proposer must ensure that the alignment scans are within the allowed limits. ALIGN exposures may be interleaved with STIS science exposures as part of either a Tip/Tilt Raster Scan or a Focus Scan. Target Name The special value NONE must be specified. Aperture or FOV Do not enter a value. Spectral Element Do not enter a value. Wavelength Do not enter a value. 222 Chapter 10: Space Telescope Imaging Spectrograph (STIS) Optional Parameters Note that no Optional Parameters may be used with ALIGN mode when the REQ UPLINK Special Requirement is used. FOCUS (Restricted) =0 (default); –4791 to +4791 (steps) Restricted—Specifies the relative position from a nominal zero position of the STIS focus mechanism, in motor steps. The absolute position of the nominal zero is set by real-time command. XTILT, YTILT (Restricted) =0 (default); –115 to +115 (steps) (for either) Restricted—Specifies the relative position from a nominal zero position of the STIS X or Y tilt alignment mechanism, in motor steps. The absolute position of the nominal zero is set via real-time command. Note: If a particular position for any of these mechanisms is needed for a series of exposures, the appropriate parameter (FOCUS, XTILT, or YTILT) must be specified with the same value on every exposure in the series. If any parameter is specified on an exposure and then omitted on the subsequent exposure, the corresponding mechanism position will be moved back to the nominal zero. Number of Iterations The Number_Of_Iterations must be 1. Time Per Exposure Proposers may specify a positive value of Time_Per_Exposure to provide for additional time after the move has completed to wait prior to the start of the subsequent STIS exposure. This time may be desirable if, for instance, the Corrector move in the ALIGN Mode exposure could adversely affect the thermal environment (due to running the motors) and a cool-down time is required before the science exposure. If no wait is needed, enter 0S. 223 Mode = ANNEAL (Restricted) Configuration = STIS (Restricted) Restricted—This Mode allows specification of periods of time during which STIS should be configured to anneal the CCD for removal of hot pixels. The total annealing time will be the specified exposure time plus a minimum default value (12 hours). ANNEAL exposures do not collect science data. Because of the long time required to configure the STIS for ANNEAL Mode, ANNEAL exposures must be in a visit with no other exposures. Target Name The special value NONE must be specified. Aperture or FOV Do not enter a value. Spectral Element Do not enter a value. Wavelength Do not enter a value. Optional Parameters There are no Optional Parameters in this Mode. Number of Iterations The Number_Of_Iterations must be 1. Time Per Exposure The value is the time to be added to the minimum default value (12 hours), which will determine the total time for the annealing procedure. 224 Chapter 10: Space Telescope Imaging Spectrograph (STIS) Mode = MSMOFF (Restricted) Configuration = STIS (Restricted) Restricted—This mode is used for special MSM offset management. One can set special offsets, zero the offsets, or restore the current month’s offsets. This mode will be used in special calibration programs that require special MSM offsetting. MSMOFF exposures should come after all ACQ and ACQ/PEAK exposures in a visit. Target Name The special value NONE must be specified. Aperture or FOV Do not enter a value. Spectral Element Do not enter a value. Wavelength Do not enter a value. Optional Parameters 1. The first MSMOFF mode exposure in a visit must specify SETOFFSET, GRATING1, and, optionally, GRATING2 and GRATING3. 2. An intermediate MSMOFF mode exposure in a visit must specify SETOFFSET, GRATING1 (only), and WAVELENGTH (if needed). 3. The last MSMOFF mode exposure in a visit must specify SETOFFSET = RESTORE, GRATING1, and, optionally, GRATING2 and GRATING3. 225 SETOFFSET (Restricted) = ZERO, RESTORE, or <dither ID> (no default) This required parameter selects the MSM offset function. ZERO sets the MSM offsets to 0 for the requested grating(s). RESTORE resets to the current month’s MSM offsets for the requested grating(s). <dither ID> causes a different month’s offsets to be loaded for the requested grating(s). The <dither ID> is a 4 digit integer composed of a 2-digit month number followed by ’00’ (e.g. 0300 would indicate the March MSM offsets). GRATING1 (Restricted) = ALL, G140L, G140M, E140H, E140M, G230L, G230M, E230H, E230M (no default) This required parameter specifies the first grating or requests all gratings. GRATING2 (Restricted) = G140L, G140M, E140H, E140M, G230L, G230M, E230H, E230M (no default) Specifies the second grating, if applicable. GRATING3 (Restricted) = G140L, G140M, E140H, E140M, G230L, G230M, E230H, E230M (no default) Specifies the third grating, if applicable. WAVELENGTH (Restricted) = <a legal wavelength for the GRATING1 optic> (no default) This optional parameter is used only for intermediate MSMOFF mode exposures within a visit. It must be set whenever the spectral element and central wavelength of the prior STIS exposure match the next STIS exposure and the spectral element matches GRATING1 (Note well: GRATING1 cannot be set to ALL when WAVELENGTH is specified). WAVELENGTH should be set to the central wavelength of the next STIS exposure. Number of Iterations The Number_Of_Iterations must be 1. Time Per Exposure DEF. 226 Chapter 10: Space Telescope Imaging Spectrograph (STIS) REFERENCE INFORMATION STIS Central Wavelengths Table 10.2: Supported Central Wavelengths for STIS Gratings Spectral Element Central Wavelength (Angstroms) E140H 1234, 1271, 1307, 1343, 1380, 1416, 1453, 1489, 1526, 1562, 1598 E140M 1425 E230H 1763, 1813, 1863, 1913, 1963, 2013, 2063, 2113, 2163, 2213, 2263, 2313, 2363, 2413, 2463, 2513, 2563, 2613, 2663, 2713, 2762, 2812, 2862, 2912, 2962, 3012 E230M 1978, 2124, 2269, 2415, 2561, 2707 G140L 1425 G140M 1173, 1218, 1222, 1272, 1321, 1371, 1387, 1400, 1420, 1470, 1518, 1540, 1550, 1567, 1616, 1640, 1665, 1714 G230L 2376 G230LB 2375 G230M 1687, 1769, 1851, 1884, 1933, 2014, 2095, 2176, 2257, 2338, 2419, 2499, 2579, 2600, 2659, 2739, 2800, 2818, 2828, 2898, 2977, 3055 G230MB 1713, 1854, 1995, 2135, 2276, 2416, 2557, 2697, 2794, 2836, 2976, 3115 G430L 4300 G430M 3165, 3305, 3423, 3680, 3843, 3936, 4194, 4451, 4706, 4781, 4961, 5093, 5216, 5471 G750L 7751 G750M 5734, 6094, 6252, 6581, 6768, 7283, 7795, 8311, 8561, 8825, 9286, 9336, 9806, 9851 PRISM 1200, 2125 227 Table 10.2 (cont): Available but Unsupported Wavelengths for STIS Gratings Spectral Element Central Wavelength (Angstroms) G140L 1575a G750L 8975 G750M 10363 a. With grating G140L, a central wavelength of 1575 Å is illegal in ACCUM mode and configurations of STIS/FUV-MAMA or STIS/NUV-MAMA when the target is WAVE. Table 10.2 (cont): Wavelengths for Restricted Gratings Spectral Element Central Wavelength (Angstroms) X140H (Restricted) 1232, 1269, 1305, 1341, 1378, 1414, 1451, 1487, 1523, 1560, 1587 X140M (Restricted) 1425 X230H (Restricted) 1760, 2010, 2261, 2511, 2760, 3010 (primary tilts) X230M (Restricted) 1975, 2703 (primary tilts) STIS Internal Calibration Targets The following internal calibration targets are available for the STIS. These should not be included in your proposal if the routine calibrations are sufficient for your program. See the STIS Instrument Handbook for details. Target_Name = WAVE An observer-specified wavelength calibration exposure for a selected spectral element, central wavelength, and aperture. Permitted in the STIS/CCD, STIS/FUV–MAMA, and STIS/NUV–MAMA configurations, only in ACCUM Mode. No optional parameters may be specified. The number of iterations must be 1. Note: For the STIS/CCD configuration, a gain of 4 e/DN will be used. Observer-specified wavecals may be used in addition to or in place of automatic wavecals. 228 Chapter 10: Space Telescope Imaging Spectrograph (STIS) Exposures with the WAVE internal target must immediately precede or follow an external science exposure (i.e., an ACCUM or TIME–TAG Mode exposure with an external pointing) which uses the same spectral element and central wavelength as the WAVE exposure. These exposures will use the same calibration lamp configuration as the automatic wave calibrations discussed below (based on the spectral element, central wavelength, and aperture specified). If the exposure time for a WAVE exposure is specified as DEF, the same default exposure time as the automatic wave calibrations will be used. Otherwise, the specified exposure time will be used. To avoid overuse of the line lamps, the exposure time should not exceed 5 minutes. An ACCUM Mode wavelength calibration will be automatically performed for external STIS/CCD, STIS/FUV–MAMA, and STIS/NUV–MAMA spectrographic science exposures which use ACCUM or TIME–TAG Mode at a single central wavelength with any of the spectral elements in Table 10.2. A wavelength calibration exposure will be added prior to the first such science exposure and after each subsequent science exposure at the same central wavelength if more than 40 minutes of visibility time have elapsed since the previous wavelength calibration (see the STIS Instrument Handbook for an explanation). The calibration lamp configuration, exposure time, and calibration aperture (if different from the science aperture) will be based on the grating, central wavelength, and aperture of the science exposure. Setting WAVECAL=NO will disable all automatic wavecals for that entire visit. For a detailed description of wavelength calibration exposures, see the STIS Instrument Handbook. Aperture Any legal aperture. Spectral Element Any legal value except MIRROR. The following are available as Restricted spectral elements: X140H, X140M, X230H, and X230M. Optional Parameter No Optional Parameters are allowed for a WAVE exposure except CR-SPLIT=NO, and no other value of CR-SPLIT is legal. 229 Target_Name = CCDFLAT A calibration exposure using the internal STIS CCD flat field lamps. Observations utilizing the G750L and G750M elements at wavelengths longer than about 7000 Angstroms are affected by fringing in the CCD. Due to shifting of the spectrum relative to the detector caused by the Mode Select Mechanism uncertainty (see the STIS Instrument Handbook), the reference flats taken by the Institute and maintained in the Calibration Data Base will often not rectify the fringes as well as a flat field taken contemporaneously with the science data at the same Mode Select Mechanism setting (i.e., without moving the grating wheel between the science and flat field observations). A CCDFLAT exposure is permitted only with the STIS/CCD configuration in ACCUM mode. No optional parameters except BINAXIS1 and BINAXIS2 are permitted. The number of iterations must be 2. A CCDFLAT exposure is taken to calibrate fringing. The user may specify Time_Per_Exposure as DEF, in which case the default exposure time is used, or as a duration less than the default exposure time. The default exposure time is: MAX {0.1 sec, [Time_Factor*0.1/(Width*BINAXIS1*BINAXIS2)]}, where Time_Factor as a function of Spectral Element and Wavelength is given in Table 10.3: Time_Factor for Spectral Elements and Wavelenghts.. Width (in arcsec) can be obtained from Table 10.4: Supported STIS Apertures and BINAXIS1 and BINAXIS2 are defined on page 211. The default is set to BINAXIS1=1 and BINAXIS2=1, but you may specify a value of 1, 2, or 4 for either quantity. Note: A gain of 4 e/DN will be used with Target = CCDFLAT. Exposures with the CCDFLAT internal target must immediately precede or follow an external science exposure (i.e., an ACCUM exposure with an external pointing) which uses the same spectral element and central wavelength as the CCDFLAT exposure. The STIS Instrument Handbook describes the use of CCDFLAT and recommends the following procedure in RPS2: • Specify Target_Name=CCDFLAT to indicate that the exposure is a fringe flat. GAIN=4 is automatically used, and the exposure utilizes two bulbs in the tungsten lamp. • Specify Number_of_Iterations=2, to allow cosmic ray rejection and to assure adequate signal to noise. (Other STIS pure parallel exposures may not have Number_of_Iterations>1, but CCDFLAT is an exception.) 230 Chapter 10: Space Telescope Imaging Spectrograph (STIS) • Specify Config, Opmode, Sp_Element, and Wavelength. Config must be STIS/CCD. Opmode must be ACCUM. Sp_Element and Wavelength must be from Table 10.3: Time_Factor for Spectral Elements and Wavelenghts.. • Specify Aperture, using one of those listed below for CCDFLAT. For a point source, you will want to use the appropriate small echelle slit; for an extended source, you will want to use the same slit for the flat as for the science. • Specify Time_Per_Exposure as DEFAULT. The default exposure time (in seconds) is the Time_Factor in Table 10.3: Time_Factor for Spectral Elements and Wavelenghts. and assures a signal to noise of 100 per pixel over the wavelength range of 6000 Å to 1 micron. You may also specify your own value for Time_Per_Exposure, but it must then be shorter than the default. Note that CCD flats are moved into the occultation period by RPS2 whenever they occur in the first or last exposure in an orbit. Fringe flats only work if they are taken with no movement of the Mode Select Mechanism: Be sure to place the fringe flat exposure immediately before or after the science exposure to which it pertains. In some instances (such as a long series of exposures), you may wish to bracket your science observing with fringe flats in order to take into account any possible thermal shifts Table 10.3: Time_Factor for Spectral Elements and Wavelenghts. Spectral Element Central Wavelength Time_Factor (sec) G750L 7751 25 G750M 6768 90 7283 80 7795 80 8311 85 8561 85 8825 70 9286 60 9336 50 9806 85 9851 90 231 Aperture 52X0.05, 52X0.1, 52X0.2, 52X0.2F1, 52X0.5, 52X2, 0.3X0.09, or 0.2X0.06. The 0.3X0.09 and 0.2X0.06 slits listed under target name CCDFLAT are intended for use on point-source targets, and the remaining slits are intended for use on diffuse targets. To choose the best slit, see the STIS Instrument Handbook. Spectral Element Must be G750L or G750M. A central wavelength must be specified for CCDFLAT. Use only the central wavelengths in Table 10.3: Time_Factor for Spectral Elements and Wavelenghts. above; do not use Table 10.2. Target_Name = BIAS (Restricted) A CCD readout without an exposure (i.e., the exposure time must be specified as 0S) in order to measure the detector bias. Permitted only with the STIS/CCD configuration in ACCUM Mode. Optional parameters are limited to GAIN, BINAXIS1, BINAXIS2, SIZEAXIS1, SIZEAXIS2, CENTERAXIS1, CENTERAXIS2, PREFLUSH, and AMP. A BIAS exposure is allowed to have CR-SPLIT=NO, but no other value of CR-SPLIT is legal. Aperture DEF = no change from previous exposure. Spectral Element DEF = no change from previous exposure. Target_Name = DARK (Restricted) An exposure taken with the detector shuttered from external light to measure the detector dark current. Optional parameters in the STIS/CCD configuration are limited to GAIN, BINAXIS1, BINAXIS2, SIZEAXIS1, SIZEAXIS2, CENTERAXIS1, CENTERAXIS2, PREFLUSH, and AMP. Optional parameters in the MAMA configurations are limited to BINAXIS1, BINAXIS2, and BUFFER–TIME. 232 Chapter 10: Space Telescope Imaging Spectrograph (STIS) A CCD DARK exposure is allowed to have CR-SPLIT=NO, but no other value of CR-SPLIT is legal. Aperture DEF = no change from previous exposure. Spectral Element DEF = no change from previous exposure. STIS Coordinate System Knowledge of the STIS coordinate system relative to the spacecraft coordinate system is necessary to use the POSition TARGet <X-value>, <Y-value> Special Requirement properly. The Figure below shows the sense of the U2 and U3 axes for the various STIS apertures. 233 Figure 10.1: STIS coordinate system (shown projected onto the sky, as used with the POS TARG Special Requirement). Axis 2 Y Pos-Targ +U3 +U3 Spatial 45 Axis 1 X Pos-Targ +U2 +U2 Dispersion IMAGING Axis 2 X pos Y pos (Spatial) Y pos (Spatial) Y pos Spatial LONG SLITS SQUARE SLITS CCD or MAMA X pos (Disp) X pos (Disp) Axis 1 (1,1) Dispersion SLIT LONG DIMENSION ALONG DISP Y pos (Spatial) (e.g. Echelle 0.1 x 0.2) ND QUAD APERTURES Y Y pos (+4 5 o) X pos Y pos (Spatial) OCCULTATION BARS PLANETARY APERTURES ND2 ND1 X pos (Disp) Y X ND3 X ND4 WEDGE Y pos X pos (Disp) X pos Y Y X X 234 Chapter 10: Space Telescope Imaging Spectrograph (STIS) The Official STIS Aperture List for Cycle 10 Table 10.4: Supported STIS Apertures lists the apertures in STIS that are Supported for Cycle 10; they are noted with an “OK.” This table has been carefully checked for completeness and accuracy, and should be taken as the final word for Cycle 10. Revisions to documents occur as needed to keep them up-to-date. If a discrepancy is found in this or other documents (such as the Data Handbook or STIS Instrument Handbook), the table here should be considered definitive and correct. Table 10.4: Supported STIS Apertures Dimensions (arcsec) Description STIS/CCD Length Width 0.1X0.03 0.1X0.09 0.1X0.2 0.2X0.06 0.2X0.09 0.2X0.2 0.2X0.05ND 0.2X0.06FPA 0.2X0.06FPB 0.2X0.06FPC 0.2X0.06FPD 0.2X0.06FPE 0.2X0.2FPA 0.2X0.2FPB 0.2X0.2FPC 0.2X0.2FPD 0.2X0.2FPE 0.3X0.05ND 6X0.2 MIRROR ACQ ACQ/PEAK ACCUM STIS/FUV-MA STIS/NUV-MAMA MA ACCUM or ACCUM or TIME-TAG TIME-TAG MIRROR G230LB G230MB G430L G430M G750L G750M MIRROR G230LB G230MB G430L G430M G750L G750M MIRROR G140L G140M E140H E140M MIRROR G230L G230M E230H E230M PRISM Aperture Name F means a forbidden combination; R means a Restricted combination; A means Available but Unsupported Echelle Slits 0.1 0.025 Very high spectral resolution F Ok Ok Ok Ok Ok Ok Ok A A A A A A A R A A Ok Ok R 0.1 0.09 Echelle slit F A A A A A A A A A A A A A A R A A A A R 0.1 0.2 Echelle slit F A A A A A A A A A A A A A A R A A A A R 0.2 0.063 Echelle slit F Ok Ok Ok Ok Ok Ok Ok A A A A A A A R A A A Ok R 0.2 0.09 Echelle slit F Ok Ok Ok Ok Ok Ok Ok A A A A A A A R A A Ok A R 0.2 0.2 Echelle slit F Ok Ok Ok Ok Ok Ok Ok A A A A A A A R A A Ok Ok R 0.2 0.05 Filtered Slit; Neutral Density=2.0 F Ok Ok Ok Ok Ok Ok Ok A A A A A A A R A A Ok Ok R 0.2 0.063 Offset in dispersion direction F Ok Ok Ok Ok Ok Ok Ok A R R R R R R R R R Ok Ok R 0.2 0.063 Offset in dispersion direction F Ok Ok Ok Ok Ok Ok Ok A R R R R R R R R R Ok Ok R 0.2 0.063 Offset in dispersion direction F Ok Ok Ok Ok Ok Ok Ok A R R R R R R R R R Ok Ok R 0.2 0.063 Offset in dispersion direction F Ok Ok Ok Ok Ok Ok Ok A R R R R R R R R R Ok Ok R 0.2 0.063 Offset in dispersion direction F Ok Ok Ok Ok Ok Ok Ok A R R R R R R R R R Ok Ok R 0.2 0.2 Offset in dispersion direction F Ok Ok Ok Ok Ok Ok Ok A R R R R R R R R R Ok Ok R 0.2 0.2 Offset in dispersion direction F Ok Ok Ok Ok Ok Ok Ok A R R R R R R R R R Ok Ok R 0.2 0.2 Offset in dispersion direction F Ok Ok Ok Ok Ok Ok Ok A R R R R R R R R R Ok Ok R 0.2 0.2 Offset in dispersion direction F Ok Ok Ok Ok Ok Ok Ok A R R R R R R R R R Ok Ok R 0.2 0.2 Offset in dispersion direction F Ok Ok Ok Ok Ok Ok Ok A R R R R R R R R R Ok Ok R 0.33 0.05 Filtered Slit; Neutral Density=3.0 F Ok Ok Ok Ok Ok Ok Ok A A A A A A A R A A Ok Ok R 6.0 0.2 Echelle slit F Ok Ok Ok Ok Ok Ok Ok A A A A A A A R A A Ok Ok R A A A A A A A R R R R R R R R R R A A A A A A A A A R R R R R R R R R R A A Ok Ok Ok A Ok Ok Ok Ok Ok Ok Ok Ok Ok Ok Ok Ok Ok Ok Ok Ok A A Ok A Ok Ok Ok Ok Ok Ok Ok Ok Ok Ok Ok Ok Ok Ok A A A A A A A R R R R R R R R R R A A 235 Description STIS/CCD Length Width 52X0.05 52X0.2F1 52.0 52.0 52.0 52.0 0.034 0.1 0.2 0.2 52X0.2F1–R 52.0 0.2 52X0.5 52.0 52.0 0.5 2.0 F25CN182 24.7 50.0 50.0 24.7 24.7 24.7 50.0 50.0 24.7 24.7 F25CN270 24.7 24.7 F25LYA 24.7 24.7 F25MGII 24.7 24.7 24.7 24.7 24.7 24.7 52X0.1 52X0.2 52X2 25MAMA 50CCD 50CORON F25CIII F25ND3 F25ND5 Long slit First order slit First order slit First order slit; Fiducial=0.5 arcsec Reference for peaking up in slit width First order slit First order slit Clear MAMA aperture Clear CCD aperture Coronograph aperture CIII filtered NUV–MAMA 182nm Cont. filtered NUV–MAMA 270nm Cont. filtered NUV–MAMA Lyman-alpha filtered FUV–MAMA MGII filtered NUV–MAMA ND 3 filtered MAMA & CCD ND 5 filtered MAMA & CCD ACQ/PEAK First-Order Slits F Ok Ok Ok Ok Ok F Ok Ok Ok Ok Ok F Ok Ok Ok Ok Ok F Ok Ok Ok Ok Ok F ACCUM Ok Ok Ok Ok Ok Ok Ok Ok A A A A Ok Ok Ok Ok Ok Ok Ok Ok Ok Ok Ok Ok Ok Ok Ok Ok Ok Ok Ok Ok Ok Ok Ok Ok R R R R Ok Ok Ok Ok Ok Ok Ok Ok Ok A A A Ok A A A R R R R Ok Ok Ok Ok Ok Ok Ok Ok Ok A A A Ok A A A Ok A Ok A Ok Ok Ok Ok Ok Ok Ok F F F F F F F F F F F F F F F F F F F R R R R R F R R R R R Large Apertures F F F F F F Ok F F F F F F F F F F F F F F F F F F F F F F F R R A Ok Ok Ok Ok Ok Ok R Ok Ok A A R Ok Ok A A Ok R R A Ok Ok Ok Ok Ok Ok R Ok Ok A A R Ok Ok A A Ok F F F F F F F F F F F Ok Ok R R F Ok R R R F Ok R R R F Ok R R R F Ok R R R F Ok R R R F Ok R R R Ok F R F F Ok F R F F Ok F R F F Ok F R F F Ok F R F F Ok F R Ok Ok Ok F R A A Ok F R A A Ok F R A A Ok F R A A Ok F R A A F F F F F F F F R R R R R R R F F F F F Ok A A A A A F F F F F F F F R R R R R R R Ok A A A A F F F F F F F Ok Ok F F F F F F F R R R R R R R F F F F F Ok Ok Ok Ok Ok Ok F F F F F F F Ok A A A A A A Ok Ok Ok Ok Ok Ok Ok Ok Ok Ok Ok F F F F F F F Ok A A A A A A Ok Ok Ok Ok Ok Ok Ok Ok Ok Ok Ok Chapter 10: Space Telescope Imaging Spectrograph (STIS) MIRROR ACQ STIS/FUV-MA STIS/NUV-MAMA MA ACCUM or ACCUM or TIME-TAG TIME-TAG MIRROR G230LB G230MB G430L G430M G750L G750M MIRROR G230LB G230MB G430L G430M G750L G750M MIRROR G140L G140M E140H E140M MIRROR G230L G230M E230H E230M PRISM Dimensions (arcsec) 236 Aperture Name Dimensions (arcsec) Description STIS/CCD Length Width F25NDQ1 24.7 24.7 F25NDQ2 24.7 24.7 F25NDQ3 24.7 24.7 F25NDQ4 24.7 24.7 F25QTZ F28X50OIII 24.7 24.7 28.0 28.0 28.0 24.7 24.7 50.0 50.0 50.0 BAR10 50.0 50.0 WEDGEA1.0 50.0 50.0 WEDGEA1.8 50.0 50.0 WEDGEA2.0 50.0 50.0 WEDGEA2.5 50.0 50.0 F25SRF2 F28X50LP F28X50OII MIRROR ACQ ACQ/PEAK STIS/FUV-MA STIS/NUV-MAMA MA ACCUM or ACCUM or TIME-TAG TIME-TAG ACCUM MIRROR G230LB G230MB G430L G430M G750L G750M MIRROR G230LB G230MB G430L G430M G750L G750M MIRROR G140L G140M E140H E140M MIRROR G230L G230M E230H E230M PRISM Aperture Name ND step filtered MAMA & CCD R F F F F F F (Quad1) ND step filtered MAMA & CCD R F F F F F F (Quad2) ND step filtered MAMA & CCD R F F F F F F (Quad3) ND step filtered MAMA & CCD R F F F F F F (Quad4) Quartz filtered MAMA aperture F F F F F F F SrF2 filtered MAMA aperture F F F F F F F Long pass filtered CCD aperture Ok F F F F F F OII filtered CCD aperture Ok F F F F F F OIII filtered CCD aperture Ok F F F F F F Coronagraphic Apertures Bar in coronograph aperture; F R R R R R R 10.0x3.0 arcsec Wedge A in coronograph aper.; F R R R R R R Width=1.0 arcsec Wedge A in coronograph aper.; F R R R R R R Width=1.8 arcsec Wedge A in coronograph aper.; F R R R R R R Width=2.0 arcsec Wedge A in coronograph aper.; F R R R R R R Width=2.5 arcsec F Ok A A A A A A Ok Ok Ok Ok Ok Ok Ok Ok Ok Ok Ok F Ok A A A A A A Ok Ok Ok Ok Ok Ok Ok Ok Ok Ok Ok F Ok A A A A A A Ok Ok Ok Ok Ok Ok Ok Ok Ok Ok Ok F Ok A A A A A A Ok Ok Ok Ok Ok Ok Ok Ok Ok Ok Ok F F F F F R R Ok Ok Ok R R A A A R R A A A R R A A A R R A A A R R A A A R R A A A Ok Ok F F F Ok Ok F F F Ok Ok F F F Ok Ok F F F Ok Ok F F F Ok Ok F F F A A F F F A A F F F A A F F F A A F F F Ok Ok F F F R Ok R R R R R R R R R R R R R R R R R R Ok R R R R R R R R R R R R R R R R R R Ok R R R R R R R R R R R R R R R R R R Ok R R R R R R R R R R R R R R R R R R Ok R R R R R R R R R R R R R R R R R 237 Description STIS/CCD Length Width WEDGEA2.8 50.0 50.0 WEDGEB1.0 50.0 50.0 WEDGEB1.8 50.0 50.0 WEDGEB2.0 50.0 50.0 WEDGEB2.5 50.0 50.0 WEDGEB2.8 50.0 50.0 52X0.05E1 52.0 0.034 52X0.1E1 52.0 0.1 52X0.2E1 52.0 0.2 52X0.5E1 52.0 0.5 52X2E1 52.0 2.0 Wedge A in coronograph aper.; Width=2.8 arcsec Wedge B in coronograph aper.; Width=1.0 arcsec Wedge B in coronograph aper.; Width=1.8 arcsec Wedge B in coronograph aper.; Width=2.0 arcsec Wedge B in coronograph aper.; Width=2.5 arcsec Wedge B in coronograph aper.; Width=2.8 arcsec Offset 19.7 arcsec in +Y POS (spatial) from center of 52X0.05 slit Offset 19.7 arcsec in +Y POS (spatial) from center of 52X0.1 slit Offset 19.7 arcsec in +Y POS (spatial) from center of 52X0.2 slit Offset 19.7 arcsec in +Y POS (spatial) from center of 52X0.5 slit Offset 19.7 arcsec in +Y POS (spatial) from center of 52X2 slit ACQ/PEAK ACCUM F R R R R R R R Ok R R R R R R R R R R R R R R R R R F R R R R R R R Ok R R R R R R R R R R R R R R R R R F R R R R R R R Ok R R R R R R R R R R R R R R R R R F R R R R R R R Ok R R R R R R R R R R R R R R R R R F R R R R R R R Ok R R R R R R R R R R R R R R R R R F R R R R R R R Ok R R R R R R R R R R R R R R R R R Offset CCD Slits F Ok Ok Ok Ok Ok Ok Ok Ok A A A A A A F F F F F F F F F F F F Ok Ok Ok Ok Ok Ok Ok Ok A A A A A A F F F F F F F F F F F F Ok Ok Ok Ok Ok Ok Ok Ok A A A A A A F F F F F F F F F F F F R R R R R R R Ok A A A A A A F F F F F F F F F F F F R R R R R R R Ok A A A A A A F F F F F F F F F F F Chapter 10: Space Telescope Imaging Spectrograph (STIS) MIRROR ACQ STIS/FUV-MA STIS/NUV-MAMA MA ACCUM or ACCUM or TIME-TAG TIME-TAG MIRROR G230LB G230MB G430L G430M G750L G750M MIRROR G230LB G230MB G430L G430M G750L G750M MIRROR G140L G140M E140H E140M MIRROR G230L G230M E230H E230M PRISM Dimensions (arcsec) 238 Aperture Name Table 10.4 (cont): Available-but-Unsupported and Restricted STIS Apertures Dimensions (arcsec) Description STIS/CCD Length Width 0.1X0.06 0.2X0.5 0.3X0.06 0.3X0.09 0.3X0.2 0.5X0.5 1X0.06 1X0.2 6X0.06 6X0.5 2X2 31X0.05NDA 31X0.05NDB 31X0.05NDC 52X0.05F1 52X0.05F1–R 52X0.05F2 52X0.05F2–R MIRROR ACQ ACQ/PEAK ACCUM STIS/FUV-MA STIS/NUV-MAMA MA ACCUM or ACCUM or TIME-TAG TIME-TAG MIRROR G230LB G230MB G430L G430M G750L G750M MIRROR G230LB G230MB G430L G430M G750L G750M MIRROR G140L G140M E140H E140M MIRROR G230L G230M E230H E230M PRISM Aperture Name A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A F A F A A A A A F A F A A A A A F A F A A A A A F A F A A A A A F A F 239 F means a forbidden combination; R means a Restricted combination; A means Available but Unsupported Echelle Slits 0.1 0.063 F A A A A A A A A A A A A A A R A A A A R 0.2 0.5 F A A A A A A A A A A A A A A R A A A A R 0.33 0.063 F A A A A A A A A A A A A A A R A A A A R 0.33 0.09 F A A A A A A A A A A A A A A R A A A A R 0.33 0.2 F A A A A A A A A A A A A A A R A A A A R 0.5 0.5 F R R R R R R R A A A A A A A R A A A A R 1.0 0.063 F A A A A A A A A A A A A A A R A A A A R 1.0 0.2 F A A A A A A A A A A A A A A R A A A A R 6.0 0.063 F A A A A A A A A A A A A A A R A A A A R 6.0 0.5 F R R R R R R R A A A A A A A R A A A A R First-Order Slits 2.0 2.0 First order slit, clear MAMA aper. F R R R R R R R A A A A A A A A A A A A A 31.0 0.05 Filtered 1st order slit; ND=0.4 F A A A A A A A A A A A A A A R A A A A R 31.0 0.05 Filtered 1st order slit; ND=0.8 F A A A A A A A A A A A A A A R A A A A R 31.0 0.05 Filtered 1st order slit; ND=1.2 F A A A A A A A A A A A A A A R A A A A R 52.0 0.034 Long slit; Fiducial=0.5 arcsec F A A A A A A A A A A A A A A R A A A A R 52.0 0.034 Ref. for peaking up in slit width F A A A A A A A F F F F F F F F F F F F F 52.0 0.034 Long slit; Fiducial=0.9 arcsec F A A A A A A A A A A A A A A R A A A A R 52.0 0.034 Ref. for peaking up in slit width F A A A A A A A F F F F F F F F F F F F F Dimensions (arcsec) Description STIS/CCD 52X0.1B0.5 52.0 52X0.1B0.5–R 52.0 52X0.1B1.0 52.0 52X0.1B1.0–R 52.0 52X0.1B3.0 52.0 52X0.1B3.0–R 52.0 52X0.1F1 52.0 52X0.1F1–R 52.0 52X0.1F2 52.0 52X0.1F2–R 52.0 52X0.2F2 52.0 52X0.2F2–R 52.0 52X0.5F1 52.0 52X0.5F1–R 52.0 52X0.5F2 52.0 52X0.5F2–R 52.0 52X2F1 52.0 52X2F1–R 52.0 52X2F2 52.0 52X2F2–R 52.0 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.2 0.2 0.5 0.5 0.5 0.5 2.0 2.0 2.0 2.0 Occulting Bar; Width-0.5 arcsec Ref. for peaking up in slit width Occulting Bar; Width=1.0 arcsec Ref. for peaking up in slit width Occulting Bar; Width=3.0 arcsec Ref. for peaking up in slit width Long slit; Fiducial=0.5 arcsec Ref. for peaking up in slit width Long slit; Fiducial=0.9 arcsec Ref. for peaking up in slit width Long slit; Fiducial=0.9 arcsec Ref. for peaking up in slit width Long slit; Fiducial=0.5 arcsec Ref. for peaking up in slit width Long slit; Fiducial=0.9 arcsec Ref. for peaking up in slit width Long slit; Fiducial=0.5 arcsec Ref. for peaking up in slit width Long slit; Fiducial=0.9 arcsec Ref. for peaking up in slit width F F F F F F F F F F F F F F F F F F F F ACCUM MIRROR G230LB G230MB G430L G430M G750L G750M MIRROR G230LB G230MB G430L G430M G750L G750M MIRROR G140L G140M E140H E140M MIRROR G230L G230M E230H E230M PRISM Length Width ACQ/PEAK A A A A A A A A A A A A R R R R R R R R A A A A A A A A A A A A R R R R R R R R A A A A A A A A A A A A R R R R R R R R A A A A A A A A A A A A R R R R R R R R A A A A A A A A A A A A R R R R R R R R A A A A A A A A A A A A R R R R R R R R A A A A A A A A A A A A R R R R R R R R A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F R F R F R F R F R F R F R F R F R F R F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F R F R F R F R F R F R F R F R F R F R F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F A F Chapter 10: Space Telescope Imaging Spectrograph (STIS) MIRROR ACQ STIS/FUV-MA STIS/NUV-MAMA MA ACCUM or ACCUM or TIME-TAG TIME-TAG 240 Aperture Name Dimensions (arcsec) Description STIS/CCD Length Width 6X6 6.0 6.0 36X0.05N45 35.7 35.7 35.7 35.7 0.05 0.05 0.6 0.6 0.054 0.05 0.05 0.09 0.2 29.0 31.0 31.0 29.0 29.0 36X0.05P45 36X0.6N45 36X0.6P45 0.05X29 0.05X31NDA 0.05X31NDB 0.09X29 0.2X29 MIRROR ACQ ACQ/PEAK STIS/FUV-MA STIS/NUV-MAMA MA ACCUM or ACCUM or TIME-TAG TIME-TAG ACCUM MIRROR G230LB G230MB G430L G430M G750L G750M MIRROR G230LB G230MB G430L G430M G750L G750M MIRROR G140L G140M E140H E140M MIRROR G230L G230M E230H E230M PRISM Aperture Name Large Apertures (Available but Unsupported) Clear MAMA aperture F F F F F F F F A A A Planetary Apertures (Available but Unsupported) Planetary slit; –45 deg F A A A A A A A A A A Planetary slit; +45 deg F A A A A A A A A A A Planetary slit; –45 deg F R R R R R R R A A A Planetary slit; +45 deg F R R R R R R R A A A Cross-Disperser Slits (Restricted) Cross-disperser slit F R R R R R R R R R R Filtered Cross-disp. slit; ND=0.8 F R R R R R R R R R R Filtered Cross-disp. slit; ND=0.4 F R R R R R R R R R R Cross-disperser slit F R R R R R R R R R R Cross-disperser slit F R R R R R R R R R R A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A R R R R A A A A A A A A A A A A A A A A R R R R A A A A A A A A A A A A A A A A A A A A R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R 241 242 Chapter 10: Space Telescope Imaging Spectrograph (STIS) CHAPTER 11: Fine Guidance Sensors (FGS) For an explanation of this engineering-only version, see Special Note to Engineering Version Users in Chapter 1: About This Document on page 1-3. In this chapter . . . Introduction to the FGS / 244 Mode = POS Configuration = FGS / 245 Mode = TRANS Configuration = FGS / 248 Tables and Illustrations / 251 243 244 Chapter 11: Fine Guidance Sensors (FGS) Tables and Figures Table 11.1: Supported Instrument Parameters for the FGS Table 11.1: Additional Instrument Parameters for the FGS Table 11.2: Spectral Elements for the FGS Table 11.3: Internal Calibration Targets for the FGS (Restricted) Figure 11.1 The FGS POS TARG and interferometer coordinate systems. Introduction to the FGS The Instrument Configurations and Operating Modes described in the following section are used to specify exposures on the RPS2 Visit and Exposure Specifications. A summary of the legal Visit and Exposure Specifications entries is provided; more complete descriptions of Instrument Configurations, Modes, Apertures, Spectral Elements, etc. are available in the FGS Instrument Handbook. Note that many of the Optional Parameters have default values; in such cases, an entry as an Optional Parameter on the Visit and Exposure Specifications is necessary only if it is desired to override the default value. In the STScI proposal system the physical units of Optional Parameter quantities are always implicit and should never be entered by the observer. Optional Parameters whose descriptions begin with the phrase “USE WITH CAUTION” pose a risk to the intended science if a non-default value is used inappropriately. These parameters are italicized in Table 11.1. You may wish to discuss the use of these parameters with your Contact Scientist. Please note that spatial scans are not permitted with the FGSs. Also note that only FGS1 will be calibrated as a science instrument for Cycle 10. Table 11.1 lists the permitted Instrument Configuration, Operating Modes, Fields of View, Spectral Elements, and Optional Parameters for the FGS. Mode = POS Configuration = FGS 245 Table 11.1: Supported Instrument Parameters for the FGS Field of View Config Mode FGS POS PRIME, 1, 2, 3 TRANS PRIME, 1, 2, 3 Spectral Elements Optional Parameters FGS 1, 2, and 3: F583W, F5ND, F550W, PUPIL FGS 1 and 3: F605W; FGS 2 only: F650W FGS 1, 2, and 3: F583W, F5ND, F550W, PUPIL FGS 1 and 3: F605W; FGS 2 only: F650W NULL, ACQ-DIST, COUNT, FES-TIME SCANS, STEP-SIZE, ACQ-DIST Table 11.1 (cont): Additional Instrument Parameters for the FGS Config. Mode FGS POS Field of View Spectral Elements PRIME, 1, 2, 3 F605W, F583W, F5ND, F650W, F550W, PUPIL Optional Parameters LOCK (Restricted) The sections on the following pages provide further details of the entries to be made on the Visit and Exposure Specifications when a particular FGS Mode/Configuration is chosen. Mode = POS Configuration = FGS This is the basic single-star positional Operating Mode of the FGS. It may be used to measure the relative positions of fixed or slowly moving (<= 0.080 arcsec/sec) targets with a precision of 0.001 to 0.002 arcsec per single observation. To measure the relative position of a target with respect to field stars, several reference targets must be observed in the same visit. In addition, a few stars (reference and/or target) should be observed multiple times during a visit to map any positional drift of the field due to HST pointing characteristics (see the FGS Instrument Handbook). In this Operating Mode the program star or asteroid is first acquired and then held in fine lock for the specified exposure time. This procedure is repeated for the other targets. The default values of the Optional Parameters are set in this Mode to provide acceptable data for single, zero angular diameter stars. The default acquisition consists of a spiral search for a target within a radius of 15 arcsec, followed by fine-lock tracking of the target. In this default mode 246 Chapter 11: Fine Guidance Sensors (FGS) star selectors are moved to null the Fine Error Signal and their positions are recorded every 0.025 sec. Aperture or FOV PRIME FGS 1 is designated the “prime” FGS and is used for astrometry. 1, 2, 3 Requests use of a specific FGS (see Figure 11.1 The FGS POS TARG and interferometer coordinate systems.). Spectral Element The available spectral elements are listed in Table 11.2: Spectral Elements for the FGS. Only one filter can be used at a time. The F583W is the recommended element for all observations requiring the Optical Field Angle Distortion (OFAD) calibration. F583W cannot be used if the target magnitude m < 8.0. F5ND must be used if m < 8.0. An F5ND/F583W cross-filter calibration is supported. Optional Parameters NULL =YES (default), NO NULL determines whether the Star Selectors will be repositioned immediately after the FES-TIME or after a small delay. Consult with your Contact Scientist before specifying the non-default value; most astrometry programs require NULL=YES. NULL=YES (the default) means that the next fine-error-averaging time (FEAT) interval will not begin until the star selectors have completed the repositioning of the FGS instantaneous field of view (IFOV) to the null position determined by the just-completed FEAT. This is the recommended procedure for all fixed targets. NULL=NO means that the next FEAT begins immediately after the previous FEAT, implying that the star selectors will not necessarily remain fixed during the FEAT. If the FES-TIME = 0.025 sec, NULL=NO has no effect. NULL=NO is ordinarily useful only for observations of moving targets. Mode = POS Configuration = FGS 247 ACQ-DIST =DEF (default); 0.0 - 90.0 USE WITH CAUTION—This Optional Parameter determines the size (in arcsec) of the acquisition search region. The default value is 15 arcsec. A larger search radius takes more time and is generally not necessary given HST’s pointing performance. COUNT =DEF (default); 1 - 2621400 USE WITH CAUTION—The default count rate will be determined from the target V magnitude, and the filter and FGS, using simple scaling rules. The FGS Instrument Handbook should be consulted for the default background rates. These Optional Parameters are used to verify the value of FES-TIME. If a non-default value is needed, enter the expected target and sky count rates (in counts per second) for the FGS (see the FGS Instrument Handbook and consult with your Contact Scientist). FES-TIME =DEF (default); 0.025, 0.05, 0.1, 0.2, 0.4, 0.8, 1.6, 3.2 USE WITH CAUTION—This optional parameter sets the averaging time (in seconds) for the Fine Error Signal, and consequently, the interval at which the star selectors are adjusted to null the Fine Error Signal. For POS mode, the default value DEF will be calculated from the default or specified COUNT optional parameter value and the selected FGS and FILTER. For TRANSfer mode, the default (and required) value is 0.025 sec, regardless of target brightness. See the FGS Instrument Handbook for details. It is necessary that the proposer include the target V magnitude for all targets. We recommend including the B–V index so your Contact Scientist can assess your calibration needs. LOCK (Restricted) =FINE (default); COARSE; 0.0 - 1.0 Tracking of the target in fine lock (FINE) or coarse track (COARSE) may be selected with this Optional Parameter. The fraction of the exposure time in fine lock may be specified by entering a value between 0.0 and 1.0. If 0.0 is entered, fine lock will be tested but no measurements will be made. LOCK=FINE and LOCK=1.0 produce identical results. If LOCK=COARSE, the values of several other Optional Parameters are overridden: FES-TIME and NULL will be ignored. 248 Chapter 11: Fine Guidance Sensors (FGS) Special Requirements Enter the ORIENTation visit-level Special Requirement (see ORIENTation <angle1> TO <angle2>) if the arrangement of the target or reference stars requires a particular orientation of the FGS field of view. ORIENTation may be required to keep the targets in the field of view when more than one target is observed. The POSition TARGet <X-value>, <Y-value> special requirement can be used to offset a target from the aperture reference position. For the FGS, the aperture reference frame is centered near the geometric center of the field of view, and is not equivalent to the FGS detector reference frame. The two frames have different parities and origins (see Figure 11.1 The FGS POS TARG and interferometer coordinate systems. and the FGS Instrument Handbook). The SAME POSition AS <exposure> special requirement should be used to keep the position of the spacecraft held constant over the course of all observations within a visit. To ensure that all exposures within a visit are scheduled within the same orbit, use the SEQuence <exposure-list> NON-INTerruptible special requirement. Time Per Exposure The value to be entered is the photon-collecting time for measuring the position of the target. See the FGS Instrument Handbook for exposure time calculations. Mode = TRANS Configuration = FGS This Operating Mode is useful for the measurement of the relative positions of close binary stars or the sizes of extended targets. In this Mode the interference fringe pattern (or “S-curve”) is measured by scanning the FGS instantaneous FOV across the target at 45 degrees with respect to the interferometer axes and recording the Fine Error Signal (FES) every 0.025 sec. Acquisition is accomplished with a nominal 15 arcsec-radius spiral search. The S-curve is measured by a series of continuous sweeps of the field of view across the target. Moving targets can be observed if they are listed as a series of fixed targets. This observing strategy is discussed in the FGS Instrument Handbook. Mode = TRANS Configuration = FGS 249 Aperture or FOV PRIME FGS 1 is designated the “prime” FGS and is used for astrometry. 1, 2, 3 Requests use of a specific FGS (see Figure 11.1 The FGS POS TARG and interferometer coordinate systems.). Spectral Element The available spectral elements are listed in Table 11.2: Spectral Elements for the FGS. Only one filter can be used at a time. The F583W is the recommended element for programs requiring the use of POS and TRANS modes combined because of the Optical Field Angle Distortion (OFAD) calibration, which is available only for F583W. F583W cannot be used if the target magnitude m<8.0. F5ND must be used if m<8.0. Unless special S-curve calibration observations are requested, only certain combinations of filter and target color will be calibrated. Please refer to the Instrument Handbook for more information. Optional Parameters SCANS =1 (default) - 200 The value entered is the number of individual scans to make through the target, with alternate scan lines taken in the same direction. STEP-SIZE =1.0 (default); 0.3 - 10.0 The resolution by which the S-curve is sampled (in milliarcseconds) is specified by this Optional Parameter. The instantaneous field of view moves SQRT(2) x STEP-SIZE between samples (since the motion is always at 45 degrees with respect to the interferometer axes). STEP-SIZE values of 0.6 or 1.0 are recommended (see the FGS Instrument Handbook). The exposure time is calculated as follows: • Texp = [SCANS * t(samp) * L(axis)] / STEP–SIZE, where • SCANS = the number of individual scan lines, • t(samp) = 0.025 sec, and 250 Chapter 11: Fine Guidance Sensors (FGS) • L(axis) = the length of each scan in milliarcseconds as projected onto the x or y axis (see the FGS Instrument Handbook for recommendations and minimum length) The minimum scan rate is 0.035 arcsec/sec along the diagonal. ACQ-DIST =0.0 - 90.0 USE WITH CAUTION—This Optional Parameter determines the size (in arcsec) of the acquisition search region. The default value is 15 arcsec. A larger search radius takes more time and is generally not necessary given HST’s pointing performance. Time Per Exposure The exposure time (Texp) is the total photon-collecting time for all Nscan scans. The time per individual scan line is Texp/Nscan. See the discussion in STEP-SIZE above and the FGS Instrument Handbook. Special Requirements Enter the ORIENTation visit-level Special Requirement (see ORIENTation <angle1> TO <angle2>) if the arrangement of the target or reference stars requires a particular orientation of the FGS field of view. ORIENTation may be required to keep the targets in the field of view when more than one target is observed. The POSition TARGet <X-value>, <Y-value> special requirement can be used to offset a target from the aperture reference position. For the FGS, the aperture reference frame is centered near the geometric center of the field of view, and is not equivalent to the FGS detector reference frame. The two frames have different parities and origins (see Figure 11.1 The FGS POS TARG and interferometer coordinate systems. and the FGS Instrument Handbook). The SAME POSition AS <exposure> special requirement should be used to keep the position of the spacecraft held constant over the course of all observations within a visit. To ensure that all exposures within a visit are scheduled within the same orbit, use the SEQuence <exposure-list> NON-INTerruptible special requirement. Tables and Illustrations 251 Tables and Illustrations Table 11.2: Spectral Elements for the FGS Name Comments Effective Wavelength (Å) Full Width at Half Maximum (Å) F583W “Clear” filter 5830 2340 F5ND Neutral Density (5 mag) ..... ..... F605Wa “Astrometry Clear” filter 6050 1900 F650Wb “Red” filter 6500 750 F550W “Yellow” filter 5500 750 PUPIL Pupil stop 5830 2340 a. F605W is to be specified with FGS3 and FGS1. b. F650W is to be specified with FGS2 only. Table 11.3: Internal Calibration Targets for the FGS (Restricted) The following internal calibration target is available for the FGS. These should not be included in your proposal if the routine calibrations (see the FGS Cycle 10 Calibration Plan Instrument Report) are sufficient for your program. See the FGS Instrument Handbook for further details. Target Name Description DARK The star selectors slew the FGS Field of View off the Pickle Aperture and the dark counts are recorded for a time interval given by the exposure time. This occurs for target = DARK for POS Mode. ITS (Restricted) Internal Test Source activated only by special instruction. Spectral Element Time Per Exposure Any Enter a specific time 252 Chapter 11: Fine Guidance Sensors (FGS) Figure 11.1: The FGS POS TARG and interferometer coordinate systems. ON-SKY PROJECTION To Sun FGS1R FGS 3 +V3 XDET XPOS YPOS +V2 0,0 YDET YDET +U2 YPOS XPOS XDET +U3 XPOS XDET FGS 2 YPOS YDET X,YDET = Detector Coordinate Frame in Object Space X,YPOS = POS TARG Reference Frame Used in Phase 2 Proposal The POS TARG reference frame must be used to specify Special Requirements POS TARG and ORIENTation. Note that the FGS interferometer axes and POS TARG axes have different origins and parities. The interferometer reference frame is used in pipeline processing only. CHAPTER 12: Advanced Camera for Surveys (ACS) For an explanation of this engineering-only version, see Special Note to Engineering Version Users in Chapter 1: About This Document on page 3. In this chapter . . . Introduction to the ACS / 254 Mode = ACCUM Configuration = ACS/WFC / 256 Mode = ACCUM Configuration = ACS/HRC / 261 Mode = ACQ Configuration = ACS/HRC / 265 Mode = ACCUM Configuration = ACS/SBC / 267 Mode = ALIGN Configuration = ACS/WFC or ACS/HRC (Restricted) / 268 Mode = ANNEAL Configuration = ACS (Restricted) / 270 Tabular reference Data / 271 253 254 Chapter 12: Advanced Camera for Surveys (ACS) Tables and Figures Table 12.1: Supported Instrument Parameters for the ACS Table 12.2: Internal calibration Targets for the ACS Table 12.3: Spectral Elements for use with ACS/WFC and ACS/HRC Configurations Table 12.4: Wavelength Ranges for the WFC/HRC Ramp Filters Table 12.5: Spectral Elements for use with the ACS/SBC Configuration Introduction to the ACS The Instrument Configurations and Operating Modes described in this chapter are used to specify exposures on the RPS2 Visit and Exposure Specifications. The legal Visit and Exposure Specifications entries are discussed in the following sections. More complete descriptions of Instrument Configurations, Modes, Apertures, Spectral Elements, etc. are available in the ACS Instrument Handbook. Note that many of the Optional Parameters have default values. In such cases an entry as an Optional Parameter in the Visit and Exposure Specifications is necessary only if it is desired to override the default value. In the STScI proposal system, the physical units of Optional Parameter quantities are always implicit and should never be entered by the observer. The following tables lists the permitted Instrument Configurations, Operating Modes, Apertures, Spectral Elements, and Optional Parameters for the ACS. 255 Table 12.1: Supported Instrument Parameters for the ACS Optional Parameters See Table 12.3. CR-SPLIT, GAIN, SIZEAXIS2, FLASHEXP, SIZEAXIS1, PAREXP, COMPRESSION, AUTOIMAGE, CTE (Restricted), FLASHCUR (Restricted) CR-SPLIT, GAIN, SIZEAXIS2, FLASHEXP, SIZEAXIS1, PAREXP, AUTOIMAGE, CTE (Restricted), FLASHCUR (Restricted) GAIN Mode ACS/WFC ACCUM WFC, WFC1, WFC2, WFC1-FIX, WFC2-FIX, WFC1-IRAMP, WFC1-MRAMP, WFC2-MRAMP, WFC2-ORAMP ACS/HRC ACCUM HRC, HRC-FIX, See Table 12.3. HRC-OCCULT0.8, HRC-CORON1.8, HRC-CORON3.0 ACQ ACS/SBC Aperture Spectral Elements Config HRC-ACQ ACCUM SBC, SBC-FIX See Table 12.3, F220W & F606W, F220W & F550M, F220W & F502N See Table 12.5. Table 12.1 (cont): Additional Instrument Parameters for the ACS (Restricted) Config. Mode ACS/WFC ACS/HRC ACS ALIGN ALIGN ANNEAL Aperture Spectral Elements Optional Parameters FOCUS, TILT FOCUS, TILT 256 Chapter 12: Advanced Camera for Surveys (ACS) The following Restricted internal calibration targets are available for the ACS. Table 12.2: Internal calibration Targets for the ACS Target Name Descriptiona Spectral Element BIAS (Restricted) Restricted – A CCD readout without an exposure (i.e., the exposure time must be specified as 0) in order to measure the detector bias. Permitted only with the ACS/WFC and ACS/HRC in ACCUM mode. DEFb DARK (Restricted) Restricted – An exposure taken with the detector shuttered from external light to measure the detector dark current. Permitted only with the ACS/WFC, ACS/HRC, and ACS/SBC in ACCUM mode. Restricted – An exposure taken with the tungsten flat-field lamp. Permitted only with the ACS/WFC and ACS/HRC in ACCUM mode. Restricted – An exposure taken with the deuterium flat-field lamp. Permitted only with the ACS/HRC and ACS/SBC in ACCUM mode. The exposure time should normally not exceed 1000 seconds. DEFb TUNGSTEN (Restricted) DEUTERIUM (Restricted) Any element from Table 12.3. Any element from Table 12.3 or Table 12.5. a. Optional Parameters AMP and CTE may be specified with DARK and TUNGSTEN only. Optional Parameters GAIN and COMPRESSION are permitted with all internal targets. Optional Parameters FLASHEXP and FLASHCUR are not permitted with BIAS. No other Optional Parameters are permitted with internal targets. All internal target exposures will be taken as single exposures (i.e., an implicit CR-SPLIT = NO). The COMPRESSION Optional Parameter may only be used with WFC. b. DEF means the spectral element currently in place for the ACS/WFC and ACS/HRC; and means an opaque position for the ACS/SBC. Mode = ACCUM Configuration = ACS/WFC Photons are counted on the Wide Field Channel CCD as accumulated charge which is read out at the end of the exposure and converted to DN at a selectable gain. The DN are stored as 16-bit words in a data memory array. A full detector readout is 4144x4136 pixels, which includes 24 leading pixels and 24 trailing pixels of overscan per line and 40 virtual overscan lines. Aperture or FOV Allowed apertures for this mode are: WFC, WFC1, WFC2, WFC1-FIX, or WFC2-FIX 257 WFC1-IRAMP, WFC1-MRAMP, WFC2-MRAMP, WFC2-ORAMP Only the WFC aperture is permitted with the following spectral elements: POL0UV, POL60UV, POL120UV, POL0V, POL60V, POL120V, F892N, FR388N, FR423N, FR462N, FR505N, FR551N, FR601N, FR656N, FR716N, FR782N, FR853N, FR931N, FR1016N, FR459M, FR647M, FR914M. The actual position of the target within the WFC FOV for these filters will be determined by the STScI based on the spectral element specified and detector performance. The apertures WFC1-IRAMP, WFC1-MRAMP, WFC2-MRAMP, WFC2-ORAMP may also be specified with a ramp filter (any spectral element beginning with the letters “FR”). Spectral Element See Table 12.3: Spectral Elements for use with ACS/WFC and ACS/HRC Configurations. When the CTE Optional Parameter is specified as JCTWE or JCTWFS for a TUNGSTEN exposure, the proposer may specify a pair of WFC-allowed spectral elements, one from each WFC/HRC filter wheel. Wavelength If a ramp filter (any spectral element beginning with the letters “FR”) is specified, enter the value of the desired central wavelength in Ångstroms. Table 12.4: Wavelength Ranges for the WFC/HRC Ramp Filters gives the allowed minimum and maximum wavelength for each ramp filter. Note: A wavelength should not be specified if a ramp filter is not being used. Optional Parameters CR-SPLIT = 2 (default) - 8; NO Specifies the number of sub-exposures into which the exposure is to be split for the purpose of cosmic ray elimination in post-observation data processing (see the ACS Instrument Handbook). The specified exposure time will be divided equally among the number of CR-SPLIT exposures requested. If CR-SPLIT=NO, the exposure is taken without splitting. If a pattern is also specified (see Chapter 8: Pointings and Patterns on page 153), the specified number of sub-exposures will be taken at each pattern point. Any internal Exposure Specification will be taken as a single 258 Chapter 12: Advanced Camera for Surveys (ACS) exposure (i.e., an implicit CR-SPLIT=NO). Thus the CR-SPLIT parameter is not permitted to be specified for an internal exposure. GAIN = 1 (default), 2, 4, 8 (e/DN) Specifies the gain of the CCD electronics in e/DN. SIZEAXIS2 = FULL (default); 16 - 2046 (pixels) Specifies the size of a WFC subarray in detector coordinates along the AXIS2 direction. If a numeric value is specified for SIZEAXIS2, the detector subarray will be centered on the target (including any POSition TARGet offset; see POSition TARGet <X-value>, <Y-value>) in the AXIS2 dimension. WFC subarray exposures cannot use the aperture WFC unless a ramp filter is selected. Care must be taken in specifying a WFC detector subarray to ensure that the subarray is fully contained on one of the two WFC chips that comprise the WFC detector array. The default value of FULL will result in a full detector readout of 4144x4136 pixels, unless Optional Parameter SIZEAXIS1 is not FULL, in which case the readout will be SIZEAXIS1x2046 pixels. SIZEAXIS1 (Available but Unsupported) = FULL (default); 16 - 4140 (pixels) Specifies the size of a WFC subarray in detector coordinates along the AXIS1 direction. If a numeric value is specified for SIZEAXIS1 the detector subarray will be centered on the target (including any POSition TARGet offset; see POSition TARGet <X-value>, <Y-value>) in the AXIS1 dimension. The specified value of SIZEAXIS1 must be an even number of pixels. WFC subarray exposures cannot use the aperture WFC unless a ramp filter is selected. The default value of FULL for SIZEAXIS1 will result in a full detector readout of 4144x4136 pixels, unless Optional Parameter SIZEAXIS2 is not FULL, in which case the readout will be 4140xSIZEAXIS2 pixels. PAREXP (Available but Unsupported) = DEF (default), NONE, MULTIPLE Specifies the manner in which ACS/HRC parallel exposures will be automatically added to ACS/WFC external exposures during proposal processing. This parameter is not allowed to be specified on internal exposures or when Number_of_Iterations > 1, in which case no parallels will be added. If the value NONE is used, no parallel exposures will be added. The default value will cause the proposal processing software to 259 attempt to add an ACS/HRC exposure in parallel with each exposure resulting from an Exposure Specification (e.g., an HRC exposure in parallel with each CR-SPLIT WFC exposure). The value MULTIPLE is used to request automatic addition of parallel exposures explicitly. If parallels cannot be added when specifically requested, a warning will be issued. COMPRESSION (Available but Unsupported) = DEF (default), NONE, 1.3 - 3.5 Specifies the compression factor to be used in determining a fixed size for the WFC image after onboard compression. If the actual compression achieved onboard is greater than the specified value, fill data will be added to the compressed science data. If the actual compression factor is less than the specified value, science data will be lost. A value of NONE will disable onboard compression. The default value will depend on the target type and the GAIN parameter. The table of default compression factors can be found in the ACS Instrument Handbook. Compression of images with low gain values should be avoided because an actual compression factor of less than 1.3 is likely and thus science data will be lost. AUTOIMAGE (Available but Unsupported) = YES (default), NO Controls the automatic scheduling of image exposures for the purpose of spectra zero point determination of grism observations. By default, a single short image through a standard filter will be taken in conjunction with each Exposure Specification using the grism for external science observations. A value of AUTOIMAGE=NO will disable the automatic scheduling of the image exposure for the Exposure Specification on which it is specified. The parameter is allowed only on external science observations using the grism. CTE (Restricted) = NONE (default), JCTWFS, JCTWE Indicates that the exposure specified will be for the purpose of making a charge transfer efficiency (CTE) measurement. The parameter value specifies which type of CTE measurement to obtain. JCTWE is for an EPER image, while JCTWFS is for an FPR image. CTE images must be specified with TUNGSTEN as the target, except as noted below. When CTE is specified as JCTWE or JCTWFS, Optional Parameter AMP must also be specified, and GAIN and COMPRESSION are the only other Optional Parameters that may be specified. Note: To obtain a bias subtraction image with a CTE timing pattern, specify: 260 Chapter 12: Advanced Camera for Surveys (ACS) 1. The desired CTE value, 2. The target as DARK, not BIAS, and 3. Time_per_Exposure as 0.5 S. FLASHCUR (Restricted) = LOW, MEDIUM, HIGH Indicates the LED current for post-exposure, pre-readout “flash.” There is no default value. FLASHCUR may only be specified if Optional Parameter FLASHEXP is specified with a numeric value, and in that case FLASHCUR must also be specified. The ground system will assign a pre-defined value for FLASHCUR if FLASHEXP is used with one of its non-numeric values. FLASHEXP = NONE (default), SHORT, MID, LONG, 0.1 – 409.5 Indicates the duration of a post-exposure, pre-readout LED “flash.” A flash is used to ensure that CCD traps are filled, so that image photons are not lost to traps during readout. The default value of NONE means that there will be no flash. The SHORT, MID, and LONG choices select from three combinations of flash duration and flash current as defined by the ACS Calibration Team. They are intended for use in situations in which background is high, medium, and low, respectively. See the ACS Instrument Handbook for details and guidelines on the use of the post-flash capability. Calibration and engineering programs may indicate a specific time in the range of 0.1 to 409.5 seconds, in which case Optional Parameter FLASHCUR must also be specified. These times will be rounded to the nearest 0.1 sec. Number of Iterations Enter the number of times this Exposure Specification should be iterated, each with the specified Time_per_Exposure. Note: CR-SPLIT and multiple iterations are mutually exclusive capabilities. If Number_of_Iterations > 1 on an external exposure, CR-SPLIT=NO must be specified. Time Per Exposure Enter the exposure time, in seconds, for the Exposure Specification. If Number_of_Iterations = 1, the Time_per_Exposure is divided equally among the CR-SPLIT copies, if any. If Number_of_Iterations > 1, each 261 iteration comprises Time_per_Exposure. a single exposure whose duration is Note that exposure time for an individual WFC exposure, after any CR-SPLIT is applied, must be an integer multiple of 0.1 second and in the range of 0.5 to 3600 sec. The value of 0.6 sec is not allowed. Engineering and calibration proposals may specify the BIAS target, in which case Time_per_Exposure must be 0. Mode = ACCUM Configuration = ACS/HRC Photons are counted on the High Resolution Channel CCD as accumulated charge which is read out at the end of the exposure and converted to DN at a selectable gain. The DN are stored as 16-bit words in a data memory array. A full detector readout is 1062x1044 pixels, which includes 19 leading and 19 trailing pixels of overscan per line and 20 virtual overscan lines. Aperture or FOV Allowed apertures for this mode are: HRC, HRC-OCCULT0.8, HRC-CORON1.8, HRC-CORON3.0. HRC-FIX, HRC must be specified if spectral element PR200L is specified. Spectral Element See Table 12.3: Spectral Elements for use with ACS/WFC and ACS/HRC Configurations. When the CTE Optional Parameter is specified as JCTHE, JCTHFP, or JCTHFS for a TUNGSTEN exposure, the proposer may specify a pair of HRC-allowed spectral elements, one from each WFC/HRC filter wheel. Wavelength If a ramp filter (any spectral element beginning with the letters “FR”) is specified, enter the value of the desired central wavelength in Ångstroms. Table 12.4: Wavelength Ranges for the WFC/HRC Ramp Filters gives the allowed minimum and maximum wavelength for each ramp filter. Any HRC aperture may be used with the ramp filters. 262 Chapter 12: Advanced Camera for Surveys (ACS) Note: A wavelength should be not specified if a ramp filter is not being used. Optional Parameters CR-SPLIT = 2 (default) - 8; NO Specifies the number of sub-exposures into which the exposure is to be split for the purpose of cosmic ray elimination in post-observation data processing (see the ACS Instrument Handbook). The specified exposure time will be divided equally among the number of CR-SPLIT exposures requested. If CR-SPLIT=NO, the exposure is taken without splitting. If a pattern is also specified (see Chapter 8: Pointings and Patterns on page 153), the specified number of sub-exposures will be taken at each pattern point. Any internal Exposure Specification will be taken as a single exposure (i.e., an implicit CR-SPLIT=NO). Thus the CR-SPLIT parameter is not permitted to be specified for an internal exposure. GAIN = 1, 2 (default), 4, 8 (e/DN) Specifies the gain of the CCD electronics in e/DN. SIZEAXIS2 = FULL (default); 16 - 1022 (pixels) Specifies the size of an HRC subarray in detector coordinates along the AXIS2 direction. If a numeric value is specified for SIZEAXIS2, the detector subarray will be centered on the target (including any POSition TARGet offset; see POSition TARGet <X-value>, <Y-value>) in the AXIS2 dimension. The default value of FULL for SIZEAXIS2 will result in a full detector readout of 1062x1044 pixels, unless Optional Parameter SIZEAXIS1 is not FULL, in which case the readout will be SIZEAXIS1x1022 pixels. SIZEAXIS1 (Available but Unsupported) = FULL (default); 16 - 1058 (pixels) Specifies the size of an HRC subarray in detector coordinates along the AXIS1 direction. If a numeric value is specified for SIZEAXIS1, the detector subarray will be centered on the target (including any POSition TARGet offset; see POSition TARGet <X-value>, <Y-value>) in the AXIS1 dimension. The specified value of SIZEAXIS1 must be an even number of pixels. The default value of FULL for SIZEAXIS1 will result 263 in a full detector readout of 1062x1044 pixels, unless Optional Parameter SIZEAXIS2 is not FULL, in which case the readout will be 1058xSIZEAXIS2 pixels. PAREXP (Available but Unsupported) = DEF (default), NONE, MULTIPLE Specifies the manner in which ACS/WFC parallel exposures will be automatically added to ACS/HRC external exposures during proposal processing. This parameter is not allowed to be specified on internal exposures or when Number_of_Iterations > 1, in which case no parallels will be added. If the value NONE is used, no ACS/WFC parallel exposures will be added. The default value will cause the proposal processing software to attempt to add an ACS/WFC exposure in parallel with each exposure resulting from an Exposure Specification (e.g., a WFC exposure in parallel with each CR-SPLIT HRC exposure). The value MULTIPLE is used to request automatic addition of parallel exposures explicitly. If parallels cannot be added when specifically requested, a warning will be issued. Note: The addition of the WFC parallel may introduce a serial data dump into the sequence of specified exposures, delaying the next specified exposure. If this occurs and is not acceptable to you there are two actions you may take. First, you may increase the Time_per_Exposure of the following Exposure Specification by enough to accommodate a parallel dump of the WFC parallel image (contact your Program Coordinator for details). Second, you may use PAREXP=NONE on this Exposure Specification. AUTOIMAGE (Available but Unsupported) = YES (default), NO Controls the automatic scheduling of image exposures for the purpose of spectra zero point determination of grism and prism observations. By default, a single short image through a standard filter will be taken in conjunction with each Exposure Specification using a grism or prism for external science observations. A value of AUTOIMAGE=NO will disable the automatic scheduling of the image exposure for the Exposure Specification on which it is specified. The parameter is only allowed on external science observations using a grism or prism. CTE (Restricted) = NONE (default), JCTHE, JCTHFS, JCTHFP Indicates that the exposure specified will be for the purpose of making a charge transfer efficiency (CTE) measurement. The parameter value specifies which type of CTE measurement to obtain. JCTHE is for an 264 Chapter 12: Advanced Camera for Surveys (ACS) EPER image, JCTHFS is for a serial FPR image, and JCTHFP is for a parallel FPR image. CTE images must be specified with TUNGSTEN as the target, except as noted below. When CTE is specified as JCTHE, JCTHFP, or JCTHFS, Optional Parameter AMP must also be specified, and GAIN is the only other Optional Parameter that may be specified. Note: To obtain a bias subtraction image with a CTE timing pattern, specify: 1. The desired CTE value, 2. The target as DARK, not BIAS, and 3. Time_per_Exposure as 0.1 S. AMP (Restricted) = A, B, C, D (no default) Indicates the readout amplifier or amplifiers to use for this exposure. AMP must be specified when CTE is specified as other than NONE, and may not be specified at any other time. FLASHCUR (Restricted) = LOW, MEDIUM, HIGH Indicates the LED current for post-exposure, pre-readout “flash.” There is no default value. FLASHCUR may only be specified if Optional Parameter FLASHEXP is specified with a numeric value, and in that case FLASHCUR must also be specified. The ground system will assign a pre-defined value for FLASHCUR if FLASHEXP is used with one of its non-numeric values. FLASHEXP = NONE (default), SHORT, MID, LONG, 0.1 – 409.5 Indicates the duration of a post-exposure, pre-readout LED “flash.” A flash is used to ensure that CCD traps are filled, so that image photons are not lost to traps during readout. The default value of NONE means that there will be no flash. The SHORT, MID, and LONG choices select from three combinations of flash duration and flash current as defined by the ACS Calibration Team. They are intended for use in situations in which background is high, medium, and low, respectively. See the ACS Instrument Handbook for details and guidelines on the use of the post-flash capability. Calibration and engineering programs may indicate a specific time in the range of 0.1 to 409.5 seconds, in which case Optional Parameter FLASHCUR must also be specified. These times will be rounded to the nearest 0.1 sec. 265 Number of Iterations Enter the number of times this Exposure Specification should be iterated, each with the specified Time_per_Exposure. Note: CR-SPLIT and multiple iterations are mutually exclusive capabilities. If Number_Of_Iterations > 1 on an external exposure, CR-SPLIT=NO must be specified. Time Per Exposure Enter the exposure time, in seconds, for the Exposure Specification. If Number_of_Iterations = 1, the Time_per_Exposure is divided equally among the CR-SPLIT copies, if any. If Number_of_Iterations > 1, each iteration comprises a single exposure whose duration is Time_per_Exposure. Note that the exposure time for an individual HRC exposure, after any CR-SPLIT is applied, must be an integer multiple of 0.1 second and in the range of 0.1 to 3600 sec. Engineering and calibration proposals may specify the BIAS target, in which case the Time_per_Exposure must be 0. Mode = ACQ Configuration = ACS/HRC For HRC science observations using one of the coronagraphic apertures (HRC-OCCULT0.8, HRC-CORON1.8, HRC-CORON3.0), you will need to perform a target acquisition (ACQ Mode exposure) prior to the science observations in order to accurately position the target behind the occulter. In ACQ mode, the ACS onboard flight software locates the brightest target in the acquisition subarray of the HRC FOV by determining the total flux within a sequence of overlapping “check boxes” within that subarray. The target position is located within the brightest check box and HST is repositioned to place the target at the position of the small spot (HRC-CORON0.8). A slew to a different aperture for an ACCUM exposure will be separate and require a small amount of additional time. Aperture or FOV HRC-ACQ is the only valid aperture for this Mode. 266 Chapter 12: Advanced Camera for Surveys (ACS) Spectral Element In addition to any of the allowed filters or polarizer/filter pairs specified in Table 12.3: Spectral Elements for use with ACS/WFC and ACS/HRC Configurations, the filter pairs F220W & F606W, F220W & F550M or F220W & F502N are allowed for ACQ mode exposures. These paired filters should be used for bright targets that would otherwise saturate the HRC detector. The neutral density equivalents of these paired filters can be found in the ACS Instrument Handbook. Wavelength If a ramp filter (any spectral element beginning with the letters “FR”) is specified, enter the value of the desired central wavelength in Ångstroms. Table 12.4: Wavelength Ranges for the WFC/HRC Ramp Filters gives the allowed minimum and maximum wavelength for each ramp filter. Note: A wavelength should not be specified if a ramp filter is not being used. Optional Parameters There are no optional parameters available to the GO in this mode. GAIN (Available but Unsupported) = 1, 2, 4 (default), 8 (e/DN) Specifies the gain of the CCD electronics in e/DN. Number of Iterations The Number_Of_Iterations must be 1 in this Mode. Time Per Exposure The procedures to determine the exposure time for ACQ exposures are given in the ACS Instrument Handbook. Observers should take care to obtain a signal-to-noise ratio of at least 40 from their sources, integrated over the checkbox. Note that the default gain of the CCD electronics is 4 e/DN for ACQ exposures. The acquisition overhead is typically dominated by factors other than the exposure time itself, and observers may wish to consider adding extra pad to the exposure time to ensure the required signal-to-noise, taking care not to saturate the CCD pixels or to exceed the maximum acquisition exposure time. 267 Note that Time per Exposure for individual HRC exposures must be an integer multiple of 0.1 second and must be in the range of 0.1 to 300 sec. Calibration and Engineering programs may specify a longer Time_per_Exposure, but not in excess of 3600 sec. Mode = ACCUM Configuration = ACS/SBC The SBC uses a MAMA detector which is a photon-counting device that provides a two-dimensional ultraviolet capability. The MAMA accumulates photons in the ACS data buffer as they are received, producing images with 1024x1024 pixels. For a more detailed description, see the discussion of SBC ACCUM mode in the ACS Instrument Handbook. Aperture or FOV The permitted apertures for this mode are SBC or SBC-FIX. SBC must be specified if spectral element PR110L or PR130L is specified. Spectral Element See Table 12.5: Spectral Elements for use with the ACS/SBC Configuration. Wavelength No wavelength should be specified for this mode. Optional Parameters There are no Optional Parameters in this Mode. Unlike WFC or HRC, SBC exposures with a dispersing spectral element (PR110L or PR130L) will not have an additional image exposure scheduled automatically (see Optional Parameter AUTOIMAGE under ACCUM mode for HRC and WFC). If an image exposure is desired in combination with a prism exposure, it must be entered separately. It is best to place it immediately before or after the prism exposure, and in the same visit. 268 Chapter 12: Advanced Camera for Surveys (ACS) Number of Iterations Enter the number of times this Exposure Specification should be iterated. Time Per Exposure Enter the exposure time to apply to each iteration. Note that Time_per_Exposure for individual SBC exposures must be an integer multiple of 0.1 second and must be in the range of 0.1 to 3600 sec. Mode = ALIGN Configuration = ACS/WFC or ACS/HRC (Restricted) This Mode is used to move the ACS internal focus and tilt mechanisms for the WFC or HRC via stored commanding for the purpose of on-orbit alignment of the aberration correction optics. ALIGN exposures do not acquire science data and must be interleaved with science mode exposures to obtain data, with the alignment mechanisms at a variety of positions for the ground alignment process. The proposer must ensure that the alignment scans are within the allowed mechanism limits. The mechanism positions corresponding to the nominal zero positions of the alignment scan will be set via real-time command. This will be accomplished in a program by specifying an ALIGN mode exposure with the special requirement REQ UPLINK (see REQuires UPLINK). Because the positions of the mechanisms are set via real-time command, no Optional Parameters are permitted in conjunction with the REQ UPLINK Special Requirement in order to prevent commanding the mechanisms via stored commands. Target Name The special value NONE must be specified. Aperture or FOV Do not enter a value. Spectral Element Do not enter a value. 269 Wavelength Do not enter a value. Optional Parameters FOCUS = 0 (default); -858 to +858 (steps) Specifies the relative position from a nominal zero position of the focus mechanism, in motor steps. The absolute position of the nominal zero is set by real-time command. TILT = NO (default), YES Specifies whether a tilt of the corrector mechanisms will be commanded. If this parameter is set to YES, the maximum time required to move both cylinders of the tilt mechanism will be included in the alignment time. Number of Iterations The Number_of_Iterations must be 1. Time Per Exposure Proposers may specify a positive value of Time_Per_Exposure to provide for additional time after the move has completed to wait prior to the start of the subsequent ACS exposure. This time may be desirable if, for instance, the Corrector move in the ALIGN Mode exposure could adversely affect the thermal environment (due to running the motors) and a cool-down time is required before the science exposure. Special Requirements Optional parameters are not allowed to be specified for ALIGN exposures with the REQ UPLINK Special Requirement (see REQuires UPLINK). 270 Chapter 12: Advanced Camera for Surveys (ACS) Mode = ANNEAL Configuration = ACS (Restricted) This Mode allows specification of periods of time during which ACS should be configured to anneal the CCDs for removal of hot pixels. Both the WFC and HRC must be annealed at the same time due to the ACS electrical design. The total annealing time will be the specified exposure time plus a minimum default value (12 hours). ANNEAL exposures do not collect science data. Because of the long time required to configure the ACS for ANNEAL Mode, ANNEAL exposures must be in a visit with no other exposures. Target Name The special value NONE must be specified. Aperture or FOV Do not enter a value. Spectral Element Do not enter a value. Wavelength Do not enter a value. Optional Parameters There are no Optional Parameters in this Mode. Number of Iterations The Number_Of_Iterations must be 1. Time Per Exposure The value is the time to be added to the minimum default value (12 hours), which will determine the total time for the annealing procedure. 271 Tabular reference Data Spectral Elements for WFC and HRC Note that except for the polarizers, only one filter may be specified for an exposure. The polarizers must be used in combination with a filter on the other filter wheel in order to maintain focus. Thus the UV polarizers (POL0UV, POL60UV, POL120UV) must be used with a filter on wheel 2 excluding: F814W, FR914N, POL0V, POL60V, POL120V. The visible polarizers (POL0V, POL60V, POL120V) must be used with a filter on wheel 1 except for: F850LP, F892N, POL0UV, POL60UV, POL120UV. 272 Chapter 12: Advanced Camera for Surveys (ACS) Table 12.3: Spectral Elements for use with ACS/WFC and ACS/HRC Configurations Wheel Position Name Description Allowed Configurations 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 3 4 5 6 8 9 10 11 12 13 14 15 16 2 3 4 4 4 5 6 6 6 8 9 10 11 12 13 14 15 F555W F775W F625W F550M F850LP POL0UV POL60UV POL120UV F892N F606W F502N G800L F658N F475W F660N F814W FR388N FR423N FR462N F435W FR656N FR716N FR782N POL0V F330W POL60V F250W POL120V PR200L F344N F220W Johnson V SDSS i SDSS r narrow V SDSS z UV polarizer 0 deg UV polarizer 60 deg UV polarizer 120 deg methane broad V O III GRISM Hα SDSS g N II Johnson I O II Ramp O II Ramp O II Ramp Johnson B Hα ramp Hα ramp Hα ramp visible polarizer 0 deg HRC u visible polarizer 60 deg near-UV filter visible polarizer 120 deg HRC PRISM Ne V near-UV filter ACS/WFC, ACS/HRC ACS/WFC, ACS/HRC ACS/WFC, ACS/HRC ACS/WFC, ACS/HRC ACS/WFC, ACS/HRC ACS/WFC, ACS/HRC ACS/WFC, ACS/HRC ACS/WFC, ACS/HRC ACS/WFC, ACS/HRC ACS/WFC, ACS/HRC ACS/WFC, ACS/HRC ACS/WFC, ACS/HRC ACS/WFC, ACS/HRC ACS/WFC, ACS/HRC ACS/WFC, ACS/HRC ACS/WFC, ACS/HRC ACS/WFC, ACS/HRC ACS/WFC ACS/WFC ACS/WFC, ACS/HRC ACS/WFC, ACS/HRC ACS/WFC ACS/WFC ACS/WFC, ACS/HRC ACS/HRC ACS/WFC, ACS/HRC ACS/HRC ACS/WFC, ACS/HRC ACS/HRC ACS/HRC ACS/HRC 2 2 2 16 16 16 FR914M FR853N FR931N Broad Ramp IR Ramp IR Ramp ACS/WFC, ACS/HRC ACS/WFC ACS/WFC 273 Wheel Position Name 2 2 2 2 2 2 17 17 17 18 18 18 FR459M FR647M FR1016N FR505N FR551N FR601N Description Allowed Configurations Broad Ramp Broad Ramp IR Ramp O III Ramp O III Ramp O III Ramp ACS/WFC, ACS/HRC ACS/WFC ACS/WFC ACS/WFC, ACS/HRC ACS/WFC ACS/WFC Ramp Filter Wavelength Ranges Table 12.4: Wavelength Ranges for the WFC/HRC Ramp Filters Name Minimum Wavelength (Å) Maximum Wavelength (Å) WFC FOV location FR388N FR423N FR462N FR505N FR551N FR601N FR656N FR716N FR782N FR853N FR931N FR1016N FR459M FR647M FR914M 3710 4049 4420 4824 5266 5748 6274 6848 7474 8158 8905 9719 3810 5366 7574 4049 4420 4824 5266 5748 6274 6848 7474 8158 8905 9719 10609 5366 7574 10709 middle inner outer middle inner outer middle inner outer inner outer outer middle inner middle Spectral Elements for ACS/SBC Table 12.5: Spectral Elements for use with the ACS/SBC Configuration Wheel Position 3 3 2 3 Name Description F115LP F125LP MgF2 CaF2 274 Chapter 12: Advanced Camera for Surveys (ACS) Wheel Position 3 3 3 3 3 3 5 6 8 9 11 12 Name Description F140LP F150LP F165LP F122M PR130L PR110L BaF2 crystal quartz Suprasil Ly-α CaF2 PRISM LiF2 PRISM CHAPTER 13: Near Infrared Camera and Multi-Object Spectrometer (To be supported in Cycle 11) (NICMOS) For an explanation of this engineering-only version, see Special Note to Engineering Version Users in Chapter 1: About This Document on page 3. In this chapter . . . Introduction to NICMOS / 276 Mode = ACCUM Configuration = NIC1 or NIC2 or NIC3 / 278 Mode = MULTIACCUM Configuration = NIC1 or NIC2 or NIC3 / 282 Mode = ACQ Configuration = NIC2 / 289 Mode = BRIGHTOBJ Configuration = NIC1 or NIC2 or NIC3 (Available but Unsupported) / 290 Mode = ALIGN Configuration = NIC1 or NIC2 or NIC3 (Restricted) / 292 Tabular Data / 294 Illustrations / 299 275 276 Chapter 13: Near Infrared Camera and Multi-Object Spectrometer (To be sup- Tables and Figures Table 13.1: Supported Instrument Parameters for NICMOS Table 13.1: Additional Instrument Parameters for NICMOS Table 13.2: Predefined Sample Sequences for MULTIACCUM Mode (seconds) Table 13.3: Quantized Legal NICMOS TPG Expose Times Table 13.4: NICMOS Apertures Table 13.5: Spectral Elements for the NICMOS Table 13.6: Internal Calibration Targets for the NICMOS Figure 13.1 NICMOS Coordinate System. Figure 13.2 Definition of Orientation for NICMOS. Figure 13.3 Guide-Star Availability with NICMOS Patterns. This chapter is “Restricted” for Cycle 10. All text in this chapter should be considered “Restricted” even if it is not explicitly called out as such. Introduction to NICMOS There are three cameras available for use on the NICMOS. The choice of camera will be dictated by the desired filter and field of view. • Camera 1 (NIC1) provides the highest available spatial resolution with an 11x11 arcsec field of view and pixels that subtend 0.043 arcsec on a side. NIC1 will fully sample a diffraction-limited image at wavelengths 1.0 microns or greater. • Camera 2 (NIC2) provides intermediate spatial resolution with a 19.2x 19.2 arcsec field of view and 0.075 arcsec pixels. NIC2 will fully sample a diffraction-limited image for wavelengths 1.75 microns or greater. NIC2 contains a coronographic hole and must be selected for all observations that require use of this feature. • Camera 3 (NIC3) provides a large field of view, 51.2x51.2 arcsec, with 0.200 arcsec pixels. NIC3 will undersample the Point-Spread Function at all wavelengths, though some recovery of information may be possible by employing dithering techniques. NIC3 must be specified for all observations that use the grism Spectral Elements (see Table 13.5: Spectral Elements for the NICMOS). 277 Note: Target flux for NICMOS observations must be given in units of erg/(cm^2 sec Å) (see Flux Data [Flux] on page 49 or Flux Data [Flux] on page 82). The NICMOS units conversion tool on the STScI WWW pages can help you convert your source flux from J magnitude or flux in Janskys into this flux unit. The following table lists the permitted Instrument Configurations, Operating Modes, Apertures, Spectral Elements, and Optional Parameters for the NICMOS. Table 13.1: Supported Instrument Parameters for NICMOS Config. Mode Aperture Spectral Elements Optional Parameters NIC1, NIC2, NIC3 ACCUM See Table 13.4 See Table 13.5 MULTIACCUM See Table 13.4 See Table 13.5 CAMERA-FOCUS, NREAD, OFFSET CAMERA-FOCUS, SAMP–SEQ, NSAMP, OFFSET NIC2 ACQ NIC2–ACQ See Table 13.5 Table 13.1 (cont): Additional Instrument Parameters for NICMOS Spectral Elements Config. Mode Aperture NIC1, NIC2, NIC3 ACCUM See Table 13.4 See Table 13.5 MULTIACCU M See Table 13.4 See Table 13.5 BRIGHTOBJ See Table 13.4 None See Table 13.5 NIC1, NIC2, NIC3 ALIGN (Restricted) None Optional Parameters FOMXPOS, FOMYPOS, READOUT (Restricted), LAMP (Restricted) SAMP–TIME01, SAMP–TIME02,...SAM P–TIME25, FOMXPOS, FOMYPOS, READOUT (Restricted), LAMP (Restricted) CAMERA-FOCUS, CAMERA-FOCUS, FOCUS (Restricted), XTILT (Restricted), YTILT (Restricted) The following sections provide further details of the entries to be made on the Visit and Exposure Specifications when a particular NIC1, NIC2, or NIC3 Mode/Configuration is chosen. The two modes that will be used by the majority of NICMOS observers are described first: ACCUM Mode in , and MULTIACCUM Mode in . 278 Chapter 13: Near Infrared Camera and Multi-Object Spectrometer (To be sup- • ACCUM is the simplest operational mode for NICMOS observing. ACCUM exposures begin with one or more initial readouts of the array, followed by a specified integration period, and end with one or more readouts of the array (the number of initial and final readouts is the same). • MULTIACCUM is a more flexible operational mode which allows for a wide variety of initial, intermediate, and final readouts. Because of the difficulty of supplying calibrated DARK images for all possible readout sequences, it is strongly recommended that users choose one of the predefined readout sequences described in Mode = MULTIACCUM Configuration = NIC1 or NIC2 or NIC3 on page 282. More information on ACCUM and MULTIACCUM Modes can be found in Chapter 8 of the NICMOS Instrument Handbook. • ACQ is a specialized mode used for coronographic observations, and is described in . More information on this Mode can be found in Chapter 5 of the NICMOS Instrument Handbook. • BRIGHTOBJ Mode is described in . Both Modes are considered Available but Unsupported for Cycle 11. • ALIGN Mode (Restricted) is described in . Mode = ACCUM Configuration = NIC1 or NIC2 or NIC3 ACCUM is the simplest readout mode available on NICMOS. One or more non-destructive readouts occur at the beginning and at the end of the exposure. ACCUM Mode will be appropriate for many targets, particularly for short integrations of relatively bright targets. Aperture or FOV See Table 13.4: NICMOS Apertures. Spectral Elements See Table 13.5: Spectral Elements for the NICMOS. 279 Wavelength The Wavelength parameter is not required for NICMOS observations and should be left blank. Optional Parameters CAMERA-FOCUS =DEF (default); 1-2 Specifies the NICMOS focus position to be used. If DEF is specified or this parameter is omitted, NICMOS will be focussed in the best position for the selected camera. A value of 1-2 selects a compromise focus position between the optimum foci for cameras 1 and 2. This will mainly be useful with coordinated parallels, but CAMERA-FOCUS may be specified only on exposures using the primary NICMOS detector in the sequence as defined in Coordinated Parallels on page 105. CAMERA-FOCUS is allowed only with NIC1, NIC1-FIX, NIC2, or NIC2-FIX as the chosen aperture. NREAD =1 (default), 9, =1–25 Each ACCUM exposure is preceded and followed by a set of detector readouts, which are used to determine the initial and final pixel values. NREAD specifies the number of readouts. Multiple readouts may be used to reduce read noise at the cost of extra overhead. OFFSET =SAM (default), FOM Specifies the method of FOV offset to be used in a predefined pattern of offsets. If the default value of SAM is used, offsets from the target that cannot be supported by small angle maneuvers (SAMs) while locked onto the target guide stars will be executed under gyro control. After this happens, any subsequent pointings in the pattern within range of the target guide stars (such as returns to the initial target position in a chop pattern) will reacquire the guide stars. If FOM is specified, the pattern of offsets will be achieved by moving the NICMOS Field Offset Mirror rather than the telescope itself. The range of the FOM limits patterns with this option to +/– 26 arcseconds from the mechanism zero point. 280 Chapter 13: Near Infrared Camera and Multi-Object Spectrometer (To be sup- FOMXPOS, FOMYPOS (Available but Unsupported) =0.0 (default); –26.0 to +26.0 (arcseconds) (NIC1, NIC2, and NIC3 FOMXPOS) =0.0 (default); –42.0 to +10.0 (arcseconds) (NIC3 FOMYPOS only) These parameters specify the offset of the NICMOS FOV using the NICMOS Field Offset Mirror, in arcseconds on the sky in detector coordinates relative to the nominal zero position of the FOM. These parameters allow the proposer to specify a FOM FOV offset for a particular observation or an initial FOM position for a predefined offset pattern with OFFSET=FOM. Neither FOMXPOS nor FOMYPOS can exceed –26 to +26 arcsec for cameras 1 and 2. The new default FOM position for minimizing vignetting in camera 3 changes the FOMYPOS range from –42 to +10 arcsec when camera 3 is primary. The FOMXPOS range for camera 3 is the same as for cameras 1 and 2. Parallel exposures in a coordinated-parallel sequence (see Chapter 6: Parallel Science Exposures on page 101) may not use the FOMXPOS or FOMYPOS parameters. An exception to this rule is when the primary exposures use a different SI; then the FOMXPOS and FOMYPOS parameters may be used only with the first NICMOS configuration referenced in the PARallel WITH special requirement (see PARallel <parallel-exp-list> WITH <primary-exp-list>). READOUT (Restricted) =FAST (default), SLOW Specifies the detector readout rate to be used. The default value of FAST is most efficient. Use of READOUT=SLOW is not recommended, as no advantage of slow readout has been demonstrated. If you are interested in using this option, please consult a NICMOS Instrument Scientist. LAMP (Restricted) =NONE (default), FLAT1, FLAT2, FLAT3 Identifies the internal NICMOS flat field lamp to be used for the exposure. The light from the external FOV will be superimposed on the lamp illumination, so exposures using LAMP values other than NONE should be pointed to minimize the contamination of the image from astronomical sources. Parallel exposures in a coordinated-parallel sequence may not use the LAMP parameter. An exception to this rule is when the primary exposures use a different SI; then the LAMP parameter may be used only with the first NICMOS configuration referenced in the PARallel WITH Special Requirement. 281 Time Per Exposure Exposure times in ACCUM Mode are quantized. The exposure consists of a set of NREAD initial readouts, followed by a period of data accumulation, followed by a set of NREAD final readouts. The Time_Per_Exposure (in seconds) refers to the total integration time, which begins at the start of the first initial readout and ends at the start of the first final readout. The NICMOS Timing Pattern Generator (TPG) uses a list of discrete values for the time between the last initial readout and the first final readout, known as TPG expose time (TPG_TIME), which is given in Table 13.3. The specified exposure time will be one of a set of possible values allowed by the following table: NREAD Exposure Time (seconds) 1 TPG_TIME + 0.598 9 TPG_TIME + 5.158 For example, suppose the desired exposure time is 10 seconds. With NREAD=1, the ideal TPG expose time is 9.402. The closest TPG expose time to that, from Table 13.3, is 9.117. So the corresponding exposure time is 9.117 + 0.598 = 9.715 seconds. With NREAD=9, the ideal TPG expose time is 4.842. The closest TPG expose time to that is 4.781. So the corresponding exposure time is 4.781+ 5.158 = 9.939 seconds. The above is a simplified formula that assumes READOUT=FAST and is limited to NREAD=1 or 9. The complete formula, allowing NREAD to vary across its full range of 1–25, is as follows: Time_Per_Exposure = TPG_TIME NREAD) + 0.028 + (READ_TIME * where READ_TIME = 0.57 if READOUT=FAST, and 3.195 if READOUT=SLOW (Restricted). Here READ_TIME includes the flight-software read delay time between the end of one readout and the start of the next, currently 0.395 seconds. If the exposure time entered by the user is not one of the values allowed by the above formula, it will be reduced to the next lowest legal value. It is illegal to specify an exposure time which corresponds to a TPG_TIME below the minimum value of 0.0. If the brightness of the source requires a shorter exposure time, MULTIACCUM Mode is suggested instead. 282 Chapter 13: Near Infrared Camera and Multi-Object Spectrometer (To be sup- Special Requirements The three NICMOS detectors may be operated in parallel. It is strongly advised that all ACCUM observers use the exposure-level special requirement PARallel WITH (see PARallel <parallel-exp-list> WITH <primary-exp-list>) wherever possible in order to make optimal use of the NICMOS during its limited lifetime. Parallel exposures should specify the other two NICMOS configurations. Coordinated parallels are not possible with certain special requirements; see Chapter 6: Parallel Science Exposures on page 101 for details. Mode = MULTIACCUM Configuration = NIC1 or NIC2 or NIC3 MULTIACCUM is a flexible mode that allows multiple non-destructive readouts of the array during integration spaced at user-specified intervals throughout the integration, with the results from each readout being recorded onboard and returned to the ground for analysis. See the NICMOS Instrument Handbook for more information. This mode differs from the use of multiple readouts with NREAD in ACCUM Mode, because it actually produces multiple images whereas the multiple initial and final readouts in ACCUM Mode are used to reduce read noise in the generation of a single image. MULTIACCUM Mode may also be used with a single sample time to achieve integration times as short as 0.203 seconds (the shortest allowed in ACCUM Mode is 0.598 seconds). Aperture or FOV See Table 13.4: NICMOS Apertures. Spectral Elements See Table 13.5: Spectral Elements for the NICMOS. Wavelength The Wavelength parameter is not required for NICMOS observations and should be left blank. 283 Optional Parameters CAMERA-FOCUS =DEF (default); 1-2 Specifies the NICMOS focus position to be used. If DEF is specified or this parameter is omitted, NICMOS will be focussed in the best position for the selected camera. A value of 1-2 selects a compromise focus position between the optimum foci for cameras 1 and 2. This will mainly be useful with coordinated parallels, but CAMERA-FOCUS may be specified only on exposures using the primary NICMOS detector in the sequence as defined in Coordinated Parallels on page 105. CAMERA-FOCUS is allowed only with NIC1, NIC1-FIX, NIC2, or NIC2-FIX as the chosen aperture. SAMP–SEQ =SCAMRR, MCAMRR, STEP1, STEP2, STEP8, STEP16, STEP32, STEP64, STEP128, STEP256, MIF512, MIF1024, MIF2048, MIF3072, SPARS64, SPARS256 Specifies the name of a predefined sequence of times from the start of the exposure at which the nondestructive readouts (samples) are performed. The number of samples (up to 25) taken for each exposure is controlled by the NSAMP parameter (see below). Table 13.2: Predefined Sample Sequences for MULTIACCUM Mode (seconds) gives the sample times (from the start of the exposure) for each sequence. SAMP–SEQ is required for GO proposals. Four different types of sequences are provided. The SCAMRR and MCAMRR sequences are rapid sequences with linear steps, which obtain the densest temporal sampling. SCAMRR is designed for use with a single camera and provides the densest sampling available, but may not be used with multiple cameras. MCAMRR should be used if rapid sequencing is desired with two or three cameras (NIC1, NIC2, NIC3) operating in parallel. Sequences STEP1, STEP2, STEP8, STEP16, STEP32, STEP64, STEP128, and STEP256 begin with logarithmic spacing up to the given number of seconds (1–256), and then continue with linear spacing for the remainder of the sequence, with adjacent steps separated by 1–256 seconds. These sequences all include three readouts during the first second to compensate for any nonlinear effects which may arise at the start of the exposure. Sequences MIF512, MIF1024, MIF2048, and MIF3072 are intended to combine the read-noise reduction of the ACCUM strategy of taking multiple initial and final reads (NREAD > 1) with the advantages in 284 Chapter 13: Near Infrared Camera and Multi-Object Spectrometer (To be sup- dynamic range of multiple samples during the integration. These begin with eight rapid readouts, as with MCAMRR, then take nine readouts with roughly even spacing up to the given number of seconds (512, 1024, 2048, or 3072), and conclude with eight rapid readouts at MCAMRR spacing. With these patterns, NSAMP=25 is recommended to obtain the benefits of the final rapid readouts. Sequences SPARS64 and SPARS256 begin with two readouts during the first second, and then continue with sparse linear spacing for the remainder of the sequence, with adjacent steps separated by the given number of seconds (64 or 256). These are similar to STEP64 and STEP256, except that the linear sampling begins immediately after the first two readouts rather than being preceded by a series of readouts with logarithmic spacing. NSAMP =1–25 Specifies the number of samples in a predefined sequence that should actually be taken. Table 13.3 defines 25 sample times for each sequence. If an NSAMP value smaller than 25 is used, samples will be taken at only the first NSAMP times from this table. NSAMP must be specified if SAMP–SEQ is used. The number of readouts will be NSAMP plus one for the initial readout, giving a maximum of 26 readouts (the initial readout plus a maximum of 25 samples) for a single execution of a MULTIACCUM exposure. Each readout will be recorded and will appear in the final data set. OFFSET =SAM (default), FOM This is the same as in ACCUM Mode; see . SAMP–TIME01 up to SAMP–TIME25 (Available but Unsupported) =0.203 – 8590.0 seconds These parameters are mutually exclusive with the use of SAMP–SEQ and NSAMP. They should be used if the observation requires a sequence of sample times that does not fit any of the predefined sequences. The SAMP–TIMEi parameters directly specify the times from the start of the exposure at which the nondestructive readouts are performed. The number of readouts will be the number of sample times (up to a maximum of 25) plus one for the initial readout. Each readout will be recorded and will appear in the final data set. SAMP–TIME01 must be specified, and all the specified SAMP–TIMEi parameters must be given sequentially with monotonically increasing values. 285 At the times specified by the SAMP–TIMEi parameters, the detector pixels are read out nondestructively. The exposure ends at the start of the last readout of the detector array, and thus the last SAMP–TIMEi is the total exposure time. The minimum time for SAMP–TIME01, and the minimum interval between subsequent sample times, assuming a fast readout (see READOUT below), is 0.203 seconds if only a single camera is being used, and 0.302 seconds if two or three cameras (NIC1, NIC2, NIC3) are operating in parallel. If READOUT=SLOW, the minimum allowed times are 2.83 seconds for one camera and 2.93 seconds for two or three cameras. Specified sample times may be reduced by a small amount (up to 0.007 seconds) in order to satisfy instrument timing constraints. FOMXPOS, FOMYPOS (Available but Unsupported) =0.0 (default); –26.0 to +26.0 (arcseconds) (NIC1 and NIC2 only) =0.0 (default); –42.0 to +10.0 (arcseconds) (NIC3 only) These are the same as in ACCUM mode; see . READOUT (Restricted) =FAST (default), SLOW This is the same as in ACCUM Mode; see . READOUT=SLOW may not be used with SAMP–SEQ and NSAMP, because all the predefined sequences begin with sample times that are too small for a slow readout. LAMP (Restricted) =NONE (default), FLAT1, FLAT2, FLAT3 This is the same as in ACCUM Mode; see . Time Per Exposure Time_Per_Exposure must be DEF in this Mode. The exposure time is unnecessary, because it is specified by SAMP–SEQ and NSAMP. It may also be specified by the SAMP–TIMEi parameters. Special Requirements The three NICMOS detectors may be operated in parallel. It is strongly advised that all MULTIACCUM observers use the exposure-level Special Requirement PARallel WITH (see Chapter 6: Parallel Science Exposures on page 101) wherever possible in order to make optimal use of the 286 Chapter 13: Near Infrared Camera and Multi-Object Spectrometer (To be sup- NICMOS during its limited lifetime. Parallel exposures should specify the other two NICMOS configurations. Coordinated parallels are not possible with certain special requirements; see Chapter 6: Parallel Science Exposures on page 101 for details. The exposure time sequences denoted by SAMP–SEQ are defined in the following table. These values are approximated for simplicity; actual exposure times may be reduced by up to 7 msec. 287 Table 13.2: Predefined Sample Sequences for MULTIACCUM Mode (seconds) Sequence Name Sample Times SCAMRR 0.203 1.218 2.233 3.248 4.263 0.406 1.421 2.436 3.451 4.466 MCAMRR 0.303 1.818 3.333 4.848 6.363 0.303 3.989 8.979 13.969 18.959 0.303 5.981 15.951 25.921 35.891 0.303 7.981 47.951 87.921 127.891 0.303 7.981 79.951 159.921 239.891 0.303 7.981 127.969 287.969 447.969 0.303 7.981 191.965 511.955 831.945 0.606 2.121 3.636 5.151 6.666 0.606 4.987 9.977 14.967 19.957 0.606 7.975 17.945 27.915 37.885 0.606 15.975 55.945 95.915 135.885 0.606 15.975 95.945 175.915 255.885 0.606 15.975 159.969 319.969 479.969 0.606 15.975 255.963 575.953 895.943 STEP1 STEP2 STEP8 STEP16 STEP32 STEP64 0.609 1.624 2.639 3.654 4.669 0.909 2.424 3.939 5.454 6.969 0.995 5.985 10.975 15.965 20.955 0.995 9.969 19.939 29.909 39.879 0.995 23.969 63.939 103.909 143.879 0.995 31.969 111.939 191.909 271.879 0.995 31.969 191.969 351.969 511.969 0.995 31.969 319.961 639.951 959.941 0.812 1.827 2.842 3.857 4.872 1.212 2.727 4.242 5.757 7.272 1.993 6.983 11.973 16.963 21.953 1.993 11.963 21.933 31.903 41.873 1.993 31.963 71.933 111.903 151.873 1.993 47.963 127.933 207.903 287.873 1.993 63.969 223.969 383.969 543.969 1.993 63.969 383.959 703.949 1023.939 1.015 2.030 3.045 4.060 5.075 1.515 3.030 4.545 6.060 7.575 2.991 7.981 12.971 17.961 22.951 3.987 13.957 23.927 33.897 43.867 3.987 39.957 79.927 119.897 159.867 3.987 63.957 143.927 223.897 303.867 3.987 95.969 255.969 415.969 575.969 3.987 127.967 447.957 767.947 1087.937 288 Chapter 13: Near Infrared Camera and Multi-Object Spectrometer (To be supSequence Name STEP128 STEP256 MIF512 MIF1024 MIF2048 MIF3072 SPARS64 SPARS256 Sample Times 0.303 7.981 255.961 895.931 1535.901 0.303 7.981 255.961 1535.961 2815.961 0.606 15.975 383.955 1023.925 1663.895 0.995 31.969 511.949 1151.919 1791.889 1.993 63.969 639.943 1279.913 1919.883 3.987 127.967 767.937 1407.907 2047.877 0.606 15.975 511.961 1791.961 3071.961 0.995 31.969 767.961 2047.961 3327.961 1.993 63.969 1023.961 2303.961 3583.961 0.303 1.818 127.992 447.982 513.192 0.303 1.818 255.991 895.961 1025.167 0.303 1.818 511.989 1791.989 2049.201 0.303 1.818 639.988 2559.983 3073.193 0.303 255.988 575.978 895.968 1215.958 0.303 1023.996 2303.996 3583.996 4863.996 0.606 2.121 191.990 511.980 513.495 0.606 2.121 383.985 1023.955 1025.470 0.606 2.121 767.989 2047.989 2049.504 0.606 2.121 1023.987 3071.981 3073.496 0.606 319.986 639.976 959.966 1279.956 0.606 1279.996 2559.996 3839.996 5119.996 0.909 2.424 255.988 512.283 513.798 0.909 2.424 511.979 1024.258 1025.773 0.909 2.424 1023.989 2048.292 2049.807 0.909 2.424 1407.986 3072.284 3073.799 63.994 383.984 703.974 1023.964 1343.954 255.996 1535.996 2815.996 4095.996 5375.996 1.212 31.994 319.986 512.586 514.101 1.212 63.999 639.973 1024.561 1026.076 1.212 127.995 1279.989 2048.595 2050.110 1.212 127.995 1791.985 3072.587 3074.102 127.992 447.982 767.972 1087.962 1407.952 511.996 1791.996 3071.996 4351.996 5631.996 3.987 127.967 1279.961 2559.961 3839.961 1.515 63.994 383.984 512.889 514.404 1.515 127.997 767.967 1024.864 1026.379 1.515 255.989 1535.989 2048.898 2050.413 1.515 255.989 2175.984 3072.890 3074.405 191.990 511.980 831.970 1151.960 1471.950 767.996 2047.996 3327.996 4607.996 5887.996 289 Mode = ACQ Configuration = NIC2 This mode requests the NICMOS flight software to locate the brightest target in the acquisition aperture of camera 2 (one quarter of the full NIC2 FOV, or 9.6x 9.6 arcsec) and place it behind the coronographic spot of camera 2. It is only necessary as a preparation for coronography with the NIC2-CORON aperture. Two images will be taken and downlinked, each with a single non-destructive readout at the beginning and the end of the exposure. Aperture or FOV The NIC2–ACQ aperture must be used in this Mode. Spectral Elements Use any in Table 13.5: Spectral Elements for the NICMOS for the NIC2 configuration. Wavelength The Wavelength parameter is not required for NICMOS observations and should be left blank. Optional Parameters There are no Optional Parameters in this Mode. Number of Iterations Always enter 1. However, two exposures of the duration given in Time_Per_Exposure will be executed, for purposes of onboard cosmic ray elimination by the NICMOS flight software. Time Per Exposure Exposure times in ACQ Mode are quantized. The exposure consists of an initial readout, followed by a period of data accumulation, followed by a final readout. The Time_Per_Exposure (in seconds) refers to the total 290 Chapter 13: Near Infrared Camera and Multi-Object Spectrometer (To be sup- integration time, which begins at the start of the initial readout and ends at the start of the final readout. The NICMOS Timing Pattern Generator (TPG) uses a list of discrete values for the time between readouts (TPG_TIME), which is given in Table 13.3: Quantized Legal NICMOS TPG Expose Times. The specified exposure time should be one of a set of possible values allowed by the following formula: Time_Per_Exposure = TPG_TIME + 0.228 If the exposure time entered by the user is not one of the values allowed by the above formula, it will be reduced to the next lowest legal value. It is illegal to specify an exposure time below the minimum of 0.228 seconds. Special Requirements Science exposures associated with this acquisition must be identified as part of the <exposure–list> and must use the NIC2 configuration and the coronographic aperture NIC2–CORON. The Special Requirement PARallel WITH is not allowed in this Mode. The POSition TARGet <X-value>, <Y-value> special requirement may be used in this mode, but only with shared risk as an “Available but Unsupported” option. Mode = BRIGHTOBJ Configuration = NIC1 or NIC2 or NIC3 (Available but Unsupported) BRIGHTOBJ Mode may be used for bright object/filter combinations which would saturate the detector pixels in less than 0.203 seconds, the minimum MULTIACCUM integration time. In BRIGHTOBJ Mode, each pixel is reset and then read twice in succession; the detected signal is the difference between the two reads. One pixel in each of four quadrants is read at a time, with the image completed by reading each pixel in succession. The time required to complete an image is 16384 (128x128) times the exposure time. A more detailed description of BRIGHTOBJ Mode can be found in the NICMOS Instrument Handbook. Aperture or FOV See Table 13.4: NICMOS Apertures. 291 Spectral Elements See Table 13.5: Spectral Elements for the NICMOS. Wavelength The Wavelength parameter is not required for NICMOS observations and should be left blank. Optional Parameters CAMERA-FOCUS (Available but Unsupported) =DEF (default); 1-2 Specifies the NICMOS focus position to be used. If DEF is specified or this parameter is omitted, NICMOS will be focussed in the best position for the selected camera. A value of 1-2 selects a compromise focus position between the optimum foci for cameras 1 and 2. This will mainly be useful with coordinated parallels, but CAMERA-FOCUS may be specified only on exposures using the primary NICMOS detector in the sequence as defined in Coordinated Parallels on page 105. CAMERA-FOCUS is allowed only with NIC1, NIC1-FIX, NIC2, or NIC2-FIX as the chosen aperture. Time Per Exposure The BRIGHTOBJ Time_Per_Exposure is actually the time between the initial and final reads for each pixel. This must be an integer multiple of 0.001024 seconds. The Time_Per_Exposure (actually the time per pixel) is repeated 16384 times to sample the entire detector array. The maximum Time_Per_Exposure is 0.26112 seconds, which corresponds to about 72 minutes of execution time for the required 16384 repetitions across the detector array. The specified Time_Per_Exposure should allow all repetitions to be completed within anticipated target visibility windows. Special Requirements The special requirement PARallel WITH is not allowed in this Mode. 292 Chapter 13: Near Infrared Camera and Multi-Object Spectrometer (To be sup- Mode = ALIGN Configuration = NIC1 or NIC2 or NIC3 (Restricted) This Mode is used to move the NICMOS internal focus and tilt mechanisms via stored commanding for the purpose of on-orbit alignment of the aberration correction optics. ALIGN exposures do not acquire science data and must be interleaved with science mode exposures to obtain data, with the alignment mechanisms at a variety of positions for the ground alignment process. The values of the Optional Parameters specify the positions of the three alignment mechanisms in motor steps, relative to a nominal zero position. For each instrument configuration (NIC1, NIC2, NIC3), the nominal zero positions of the three mechanisms will be at the positions of the best focus for the associated camera. The mechanism positions at nominal zero for each configuration will be set via real-time command, which allows a preplanned scan of a mechanism’s position to be specified without knowledge of where in the mechanism range the scan will be executed. Since the absolute positions are set in real time, a check that the preplanned scans about the nominal zero positions do not violate the mechanism range limits cannot be performed by the scheduling system. The proposer must ensure that the alignment scans are within the allowed limits. Target Name The special value NONE must be specified. Aperture or FOV Do not enter a value. Spectral Elements Do not enter a value. Wavelength Do not enter a value. 293 Optional Parameters Note that Optional Parameters are not allowed in ALIGN mode if the REQ UPLINK Special Requirement is used. CAMERA-FOCUS (Restricted) =DEF (default); 1-2 Specifies the NICMOS focus position to be used. If DEF is specified or this parameter is omitted, NICMOS will be focussed in the best position for the selected camera. A value of 1-2 selects a compromise focus position between the optimum foci for cameras 1 and 2. FOCUS (Restricted) =0 (default); –9664 to +9664 (steps) Specifies the relative position from a nominal zero position of the NICMOS focus mechanism, in motor steps. The absolute position of the nominal zero is dependent on the instrument configuration and is set via real-time command. XTILT, YTILT (Restricted) =0 (default); –176 to +176 (steps) each Specifies the relative position from a nominal zero position of the NICMOS X or Y tilt alignment mechanism, in motor steps. The absolute position of the nominal zero is dependent on the instrument configuration and is set via real-time command. Note: If a particular position for any of these mechanisms is needed for a series of exposures, the appropriate parameter (FOCUS, XTILT, or YTILT) must be specified with the same value on every exposure in the series. If any parameter is specified on an exposure and then omitted on the subsequent exposure, the corresponding mechanism position will be moved back to the nominal zero. Number of Iterations The Number_Of_Iterations must be 1. 294 Chapter 13: Near Infrared Camera and Multi-Object Spectrometer (To be sup- Time Per Exposure Proposers may specify a positive value of Time_Per_Exposure to provide for additional time after the move has completed to wait prior to the start of the subsequent NICMOS exposure. This time may be desirable if, for instance, the PAM move in the ALIGN Mode exposure could adversely affect the thermal environment (due to running the motors) and a cool-down time is required before the science exposure. If no wait is needed, enter 0S. Special Requirements The special requirement PARallel WITH is not allowed in this Mode. Tabular Data TPG_TIME Values The following table gives the legal TPG expose times (TPG_TIME) in seconds, needed to calculate legal exposure times in ACCUM and ACQ Modes. These values are approximated for simplicity, so that exposure times derived from them may be reduced by up to 1 msec. Table 13.3: Quantized Legal NICMOS TPG Expose Times 0.000 0.042 0.078 0.128 0.207 0.329 0.523 0.831 1.318 2.085 3.311 5.246 8.314 13.181 20.887 33.108 52.476 83.177 0.014 0.050 0.085 0.143 0.229 0.358 0.573 0.910 1.440 2.286 3.626 5.755 9.117 14.450 22.908 36.305 57.544 91.198 0.021 0.057 0.100 0.157 0.250 0.394 0.630 0.996 1.584 2.508 3.978 6.307 9.999 15.848 25.116 39.811 63.092 100.000 0.028 0.064 0.107 0.172 0.272 0.437 0.688 1.096 1.734 2.752 4.365 6.917 10.959 17.375 27.539 43.645 69.178 109.648 0.035 0.071 0.114 0.186 0.301 0.473 0.759 1.197 1.906 3.017 4.781 7.583 12.020 19.052 30.198 47.860 75.858 120.221 295 131.826 208.925 301.994 419.994 575.439 839.989 1079.995 1318.252 1559.986 1859.988 2099.994 2399.996 2699.999 2939.983 3239.986 3539.988 4786.295 144.542 229.082 331.125 436.516 630.956 899.985 1096.474 1319.980 1584.887 1905.455 2219.986 2459.993 2754.225 2999.980 3299.982 3599.984 5248.072 158.484 251.188 359.998 478.628 691.826 912.006 1199.987 1379.997 1679.999 1919.984 2279.983 2511.882 2759.995 3019.950 3311.307 3630.778 5754.398 173.780 275.423 363.073 479.990 758.575 959.981 1202.259 1439.993 1737.795 2039.998 2290.864 2519.989 2819.991 3059.997 3359.999 3981.071 190.546 299.980 398.103 524.805 831.760 1000.000 1259.983 1445.434 1739.996 2089.292 2339.979 2639.981 2879.987 3179.989 3479.992 4365.154 NICMOS Apertures Each camera has two apertures defined near the center of the FOV. Only exposures using the corresponding configuration (NIC1, NIC2, NIC3) may use a given camera’s apertures. The CAMERA-FOCUS optional parameter may be used to select a compromise focus position not optimized for either NIC1 or NIC2, but intended to work well with both. One of the two FOV-center apertures (NIC1, NIC2, NIC3) is an optimal location near the center of the FOV considering detector efficiency and pixel quality, which will be updated by the STScI as the detectors change on orbit. One aperture in each camera (NIC1–FIX, NIC2–FIX, NIC3–FIX) corresponds to a fixed pixel at or near the center of the detector array, which will not change on orbit. The aperture NIC2–CORON is the location of the coronographic spot in the NIC2 camera. It will be used by science exposures which have been preceded by a target acquisition exposure using the NIC2–ACQ aperture or by a real-time acquisition image obtained using the NIC2-CORON aperture. The acquisition aperture will be slightly offset from the coronographic aperture, but within the acquisition detector subarray. 296 Chapter 13: Near Infrared Camera and Multi-Object Spectrometer (To be supTable 13.4: NICMOS Apertures Aperture NIC1 NIC1–FIX NIC2 NIC2–ACQ NIC2–CORON NIC2–FIX NIC3 NIC3–FIX Required Configuration NIC1 NIC2 NIC3 Description Optimum Center of NIC1 FOV Geometric Center of NIC1 FOV Optimum Center of NIC2 FOV Coronographic Acquisition Aperture NIC2 Coronographic Spot Geometric Center of NIC2 FOV Optimum Center of NIC3 FOV Geometric Center of NIC3 FOV NICMOS Spectral Elements The following Spectral Elements, including filters, polarizers, and grisms, are available for the three NICMOS cameras. Only exposures using the corresponding configuration (NIC1, NIC2, NIC3) may use a given camera’s spectral elements. See the NICMOS Instrument Handbook for details. 297 Table 13.5: Spectral Elements for the NICMOS Name Central Wavelength (microns) Bandwidth (microns) 18 19 20 16 17 2 15 6 13 14 11 10 12 7 8 9 0.900 0.953 0.970 1.083 1.100 1.100 1.130 1.400 1.450 1.600 1.644 1.650 1.660 1.700 1.875 1.900 0.800 – 1.000 1% 1% 1% 1.000 – 1.200 0.800 – 1.400 1% 1.000 – 1.800 1.350 – 1.550 1.400 – 1.800 1% 1.550 – 1.750 1% 1.600 – 1.800 1% 1% 5 4 3 1 1.050 1.050 1.050 N/A Paschen Alpha Paschen Alpha Continuum 0.810 – 1.290 Short Polarizer – 0 deg 0.810 – 1.290 Short Polarizer – 120 deg 0.810 – 1.290 Short Polarizer – 240 deg N/A Blank (opaque) 1.100 1.600 1.650 1.715 1.800 1.875 1.875 1.900 2.040 2.050 2.075 2.121 2.150 2.165 2.225 2.375 0.800 – 1.400 1.400 – 1.800 1.550 – 1.750 1.680 – 1.750 1.765 – 1.835 1% 1.750 – 2.000 1% 1.990 – 2.090 1.750 – 2.350 2.000 – 2.150 1% 1% 1% 2.150 – 2.300 2.300 – 2.450 Wheel Position Description Config = NIC1 F090M F095N F097N F108N F110M F110W F113N F140W F145M F160W F164N F165M F166N F170M F187N F190N POL0S POL120S POL240S BLANK S III S III Continuum He I He I Continuum Broad Band Water Fe II Fe II Continuum Config = NIC2 F110W F160W F165M F171M F180M F187N F187W F190N F204M F205W F207M F212N F215N F216N F222M F237M 18 19 20 7 8 10 9 11 2 17 6 12 13 14 15 16 Minimum Background HCO2 & C2 Continuum HCO2 & C2 Paschen Alpha Paschen Alpha Continuum Methane Imaging Broad Band H2 H2 & Brackett Gamma Continuum Brackett Gamma CO Continuum CO Band 298 Chapter 13: Near Infrared Camera and Multi-Object Spectrometer (To be sup- Name Wheel Position Central Wavelength (microns) Bandwidth (microns) POL0L POL120L POL240L BLANK 3 4 5 1 2.050 2.050 2.050 N/A 1.900 – 2.100 Long Polarizer – 0 deg 1.900 – 2.100 Long Polarizer – 120 deg 1.900 – 2.100 Long Polarizer – 240 deg N/A Blank (opaque) 1% 0.800 – 1.400 1% 1.100 – 1.900 1.400 – 1.800 1% 1% 1.200 – 2.300 1% 1% 1% 1% 1% 1% 2.150 – 2.300 2.300 – 2.500 Description Config = NIC3 F108N F110W F113N F150W F160W F164N F166N F175W F187N F190N F196N F200N F212N F215N F222M F240M 4 2 5 9 6 8 7 20 11 12 13 14 18 19 15 16 1.083 1.100 1.130 1.500 1.600 1.644 1.660 1.750 1.875 1.900 1.962 2.000 2.121 2.150 2.225 2.400 G096 G141 G206 BLANK 3 10 17 1 0.967 1.414 2.067 N/A He I He I Continuum Grism B Continuum Minimum Background Fe II Fe II Continuum Paschen Alpha Paschen Alpha Continuum SI VI SI VI Continuum H2 H2 Continuum CO Continuum CO Band 0.800 – 1.200 Grism A 1.100 – 1.900 Grism B 1.400 – 2.500 Grism C N/A Blank (opaque) NICMOS Internal Calibration Targets (Available but Unsupported) The following internal calibration targets are available for the NICMOS. These should not be included in your proposal if the routine calibrations are sufficient for your program. See the NICMOS Instrument Handbook for details. Table 13.6: Internal Calibration Targets for the NICMOS Target Name Description DARK Used for dark calibrations Spectral Element Time Per Exposure BLANK Enter a specific time 299 Illustrations Figure 13.1: NICMOS Coordinate System. +V3 +U2 HST Coordinate System (256,256) +U3 +V2 y Camera 2 x (1,1) (1,256) (256,256) y x Camera 1 (1,1) (256,256) y x Camera 3 (1,1) (256,1) to OTA V1 axis This is as projected onto the sky for the POSition TARGet Special Requirement. The POS TARG coordinate system will be aligned parallel to rows and columns in each camera as shown in the diagram above. The alignment of each camera is not exact, and the internal coordinate systems attached to each of them will differ by small rotations (probably less than 2 degrees). The FITS format data files generated for NICMOS observers will have a World Coordinate System specified appropriately for each camera. The origin of the coordinate system will be located as shown in the diagram above. 300 Chapter 13: Near Infrared Camera and Multi-Object Spectrometer (To be supFigure 13.2: Definition of Orientation for NICMOS. Coronographic Hole FGS 2 19.2” Polarizer Orientation 4.4” Radial Distance from V1 7’ 42.36” NICMOS 2 OTA +U3 4.2” 32.59” 11” 7’ 10.36” NICMOS 1 STIS 51.2” FGS 3 WFPC2 OTA +U2 W2 W4 225˚ W3 FGS 1 6’ 22.58” FOC +U3 NIC 3 +U3 NIC3 +U2 47.78” +U2 3 NICMOS 3 1 2 RED OTA (v1) Axis NICMOS APERTURES IN HST FOV BLUE Grism Dispersion NICMOS APERTURE POSITIONS NICMOS Aperture Offset Angle = 225˚ Example Binary Star; PA = 30˚ NIC3 +U3 N PA 30˚ NIC3 +U2 E N ORIENT = 225˚ PA 30˚ E Due to the linear arrangement of the three NICMOS cameras on the sky, it is sometimes advantageous to specify a unique telescope orientation. A simple example is shown above. A binary star with a position angle (PA) of 30 degrees measured east from north is to be positioned with the southern star in Camera 3 and the northern star in Camera 2. That is, we want the line connecting the two stars to lie along the NICMOS +Y axis. The resulting HST orientation is 225 + 30 = 255 degrees. (The NICMOS offset angle for orientation specifications is 225 degrees; see Table 7.4: Instrument Orientations with respect to U3-Direction.) 301 Figure 13.3: Guide-Star Availability with NICMOS Patterns. High Lat. Mid Lat. Low Lat. NICMOS Guide Star Availability Failure Rate (percent) 50 40 30 20 10 0 0 50 100 150 200 Roll Range The above graph shows the probability that guide stars will not be available (“failure rate”) as a function of the tolerance in roll (“roll range”) that the visit allows, for targets at high galactic latitude. For visits with ORIENTation requirements, the roll range would be half the difference between <angle1> and <angle2>. Note however that other special requirements, such as SAME ORIENT, ORIENT FROM, and BETWEEN, can also restrict the orientation at which a visit may be scheduled. Unavailability versus roll range is plotted for the full range of pointings within each of the NIC1, NIC2, and NIC3 apertures. Note that in all three cases the unavailability rises dramatically as the roll range shrinks to zero. The risk of not finding guide stars is considerably higher for patterns that cover the larger NIC3 aperture. For patterns larger than the NIC3 aperture, and which may approach the maximum pointing variation of 2 arcmin, unavailability will be still higher. Therefore, observations at high galactic latitude (above 45 degrees) with large patterns and tight ORIENT restrictions carry a high risk of having to be reworked later for lack of guide stars. At lower galactic latitudes, the risk still exists but is considerably reduced. 302 Chapter 13: Near Infrared Camera and Multi-Object Spectrometer (To be sup- CHAPTER 14: Cosmic Origins Spectrograph (COS) For an explanation of this engineering-only version, see Special Note to Engineering Version Users in Chapter 1: About This Document on page 1-3. In this chapter . . . Introduction to the COS / 304 Mode = TIME-TAG Configuration = COS/NUV / 304 Tabular reference Data / 306 303 304 Chapter 14: Cosmic Origins Spectrograph (COS) Tables and Figures Table 14.1: Supported Instrument Parameters for the COS Table 14.2: COS Spectral Elements and Central Wavelengths Introduction to the COS The Instrument Configurations and Operating Modes described in this chapter are used to specify exposures on the RPS2 Visit and Exposure Specifications. The legal Visit and Exposure Specifications entries are discussed in the following sections. More complete descriptions of Instrument Configurations, Modes, Apertures, Spectral Elements, etc. are available in the COS Instrument Handbook. Table 14.1: Supported Instrument Parameters for the COS Config Mode Aperture COS/NUV TIME-T PSA, BOA AG Spectral Elements Optional Parameters See Table 14.2. BUFFER-TIME Mode = TIME-TAG Configuration = COS/NUV In TIME-TAG mode, the COS detectors produce an event stream with a time resolution of 32 millisec. The X and Y pixel coordinates of each photon event are stored in a 32-bit word in data buffer memory. At the start of an exposure, and after every subsequent 32 millisec interval which contains photons events, a 32-bit tine-of-day work is written to the data memory. Aperture or FOV Allowed apertures for this mode are: • PSA: Primary Science Aperture • BOA: Bright Object Aperture Spectral Element See Table 14.2: COS Spectral Elements and Central Wavelengths. 305 Wavelength Enter the value of the central wavelength in Angstroms. Table xx gives the allowed values of the central wavelength for each grating. No wavelength should be specified if MIRROR is the Spectral Element. Consult the COS Instrument Handbook for the valid minimum and maximum wavelengths for each grating and other information. Additional Parameter BUFFER-TIME = 47 or greater (integer seconds) This is a required parameter which specifies the estimated minimum time in which half of the COS data buffer capacity will be filled during a TIME-TAG exposure. The value of BUFFER-TIME should be the half-buffer capacity (which is 2,350,000 photon events), divided by the estimated maximum average count rate in photons per second. Note that BUFFER-TIME should include expected counts from the detector dark current as well as detected photon events, taking into account the instrument’s quantum efficiency. • If BUFFER-TIME exceeds half the value of Time_Per_Exposure, the COS buffer should be adequate to hold all the data accumulated during an exposure, and the data will be transferred to the HST onboard recorder after completion of the exposure. • If BUFFER-TIME is less than half the value of Time_Per_Exposure, the exposure is expected to generate counts in excess of the COS data buffer capacity of 4,700,000 photon events. In this case data will b e transferred to the onboard recorder in 9 MByte blocks (i.e., half the buffer capacity) during the exposure. If the actual count rate is greater than the expected rate and the buffer fills up before the exposure time has completed or before the half-buffer is dumped to the data recorder, data collection will stop and any additional photon events will be lost. A conservative value of BUFFER-TIME is therefore recommended (i.e., you should err on the low side) to avoid data loss. The absolute minimum BUFFER-TIME corresponds to a maximum average count rate of 50,000 counts per second over the entire detector, which is the maximum rate at which the flight software is capable of processing the counts. 306 Chapter 14: Cosmic Origins Spectrograph (COS) Number of Iterations Number_Of_Iterations must be 1 in this mode. Time Per Exposure Enter the total time of data collection in Time_Per_Exposure. Time_Per_Exposure must be an integral multiple of 0.1 sec; if it is not it’s value will be rounded down. Time_Per_Exposure may range from 0.1 to 3600 sec. If BUFFER-TIME is less than 110 sec, photon events will be generated at a rate higher than data can be transferred out of the buffer during the exposure. In such cases Time_Per_Exposure must be no greater than twice the BUFFER-TIME so that the exposure can complete before data transfer is necessary. A BUFFER-TIME of 110 sec corresponds to a maximum average count rate of about 21,000 counts per sec. Note that TIME-TAG exposures have the potential to quickly use up the onboard storage capacity on HST. Use caution for any exposure with a Time_Per_Exposure of more than 25 times BUFFER-TIME, which corresponds to about 60,000,000 counts, or about 2 Gbits (close to 20% of HST’s onboard recorder capacity). Please see the COS Instrument Handbook. Special Requirements The Special Requirements RT ANALYSIS and PARallel WITH are not permitted with TIME-TAG exposures. Tabular reference Data Note that except for the polarizers, only one filter may be specified for an exposure. The polarizers must be used in combination with a filter on the other filter wheel in order to maintain focus. Thus the UV polarizers (POL0UV, POL60UV, POL120UV) must be used with a filter on wheel 2 excluding: F814W, FR914N, POL0V, POL60V, POL120V. The visible polarizers (POL0V, POL60V, POL120V) must be used with a filter on wheel 1 except for: F850LP, F892N, POL0UV, POL60UV, POL120UV. 307 Table 14.2: COS Spectral Elements and Central Wavelengths Configuration COS/NUV Spectral Element G185M G225M Central Wavelengths (Angstroms) 1794, 1820, 1847, 1850, 1872, 1897, 1923, 1929 2120, 2127, 2149, 2154, 2189, 2250, 2322, 2355, 2372, 2388 G230L 2635, 3000, 3360 G285M 2642, 2683, 2694, 2722, 2850, 2949, 2993, 3032, 3070 MIRROR N/A 308 Chapter 14: Cosmic Origins Spectrograph (COS) PART C: Engineering Modes (Limited Access) The chapters in this part describe the special configurations and modes, COSTAR and S/C Mode. 309 310 CHAPTER 15: Corrective Optics Space Telescope Axial Replacement (Restricted) (COSTAR) For an explanation of this engineering-only version, see Special Note to Engineering Version Users in Chapter 1: About This Document on page 1-3. In this chapter . . . Mode = DOB, Configuration = COSTAR (Restricted) / 313 Mode = FOC, Configuration = COSTAR (Restricted) / 313 Mode = SENSOR, Configuration = COSTAR (Restricted) / 314 Mode = FOS, Configuration = COSTAR (Restricted) / 315 Mode = GHRS, Configuration = COSTAR (Restricted) / 316 311 312 Chapter 15: Corrective Optics Space Telescope Axial Replacement (Restricted) The following table lists the permitted Instrument Configurations, Operating Modes and Optional parameters for the COSTAR. The instructions direct the movement of the COSTAR mirrors via stored commands and are only allowed as engineering instructions during COSTAR alignment and monitoring. Table 15.1: Instrument Parameters for the COSTAR Config. Mode Aperture Spectral Elements COSTAR DOB (Restricted ) (None) (None) FOCUS (Restricted), EVENT-FLAG (Restricted) FOC (Restricted ) (None) (None) X-TILT (Restricted), Y-TILT (Restricted), EVENT-FLAG (Restricted) SENSOR (Restricted ) (None) (None) MECH (Restricted) FOS (Restricted) (None) (None) GHRS (Restricted) (None) (None) FOCUS (Restricted) X-TILT (Restricted), Y-TILT (Restricted), EVENT-FLAG (Restricted) FOCUS (Restricted) X-TILT (Restricted), Y-TILT (Restricted), EVENT-FLAG (Restricted) Optional Parameters The tables on the following pages provide details of the entries to be made on the Visit and Exposure Specifications when the COSTAR configuration is chosen. The COSTAR mirror positions specified in the Proposal Instructions are relative to nominal zero positions. The mirror positions corresponding to the nominal zero points will be set via real-time command. The mirror mechanisms will be automatically returned to their zero positions during periods of COSTAR inactivity. Any required linking of a COSTAR mirror position to an exposure of another SI can be done by specifying a visit with COSTAR exposures followed by exposures of the other SI. The required Visit and Exposure Specifications fields for the COSTAR configuration are: operating mode, target name, exposure time, number of exposures and exposure priority. The target name must be specified as the internal target NONE. The number of exposures will be treated as 1 regardless of the number entered. The mirror position sensors will be turned on for all COSTAR exposures and will remain active for the duration of any mechanism motion plus the specified exposure time. 313 The real-time positioning of the COSTAR mirrors will require the scheduling of an uplink opportunity in conjunction with stored commanding to transition the instrument to the proper operate state. This will be accomplished in a proposal by specifying the desired COSTAR operating mode (DOB or FOC) and the REQuires UPLINK Special Requirement. Specification of optional parameters is not permitted in conjunction with the REQuires UPLINK Special Requirement. The duration of the uplink will be equal to the specified exposure time. The operating mode and the first line of the exposure comments will be made available to OPUS as information on the intended use of the uplink opportunity. Mode = DOB, Configuration = COSTAR (Restricted) The DOB Mode is used to move the Deployable Optical Bench (DOB) in order to adjust the focus of the FOC corrected light path. Optional Parameters FOCUS (Restricted) = 0 steps (default); range from -700 to +700 steps Moves the DOB to the specified position relative to its nominal zero position (0 steps). The absolute position of the nominal zero point will be set via a real-time command. EVENT-FLAG (Restricted) = NO (default); YES When this parameter is specified as YES, the execution of the stored commands pertaining to the exposure will be contingent on positive authorization from ground personnel. The parameter should be specified on each exposure line to which it applies. Mode = FOC, Configuration = COSTAR (Restricted) The FOC Mode is used to adjust the tilt of the FOC M1 mirror along local orthogonal X and Y axes in order to center the pupil image on the M2 mirror. 314 Chapter 15: Corrective Optics Space Telescope Axial Replacement (Restricted) Optional Parameters X-TILT (Restricted) = 0.0 arcsec (default); range from -1200.0 to +1200.0 arcsec Tilts the FOC M1 mirror along the local X axis to the specified angle relative to its nominal zero orientation (0.0 arcsec). The absolute orientation of the nominal zero point will be set via a real-time command. Y-TILT (Restricted) = 0.0 arcsec (default); range from -1200.0 to +1200.0 arcsec Tilts the FOC M1 mirror along the local Y axis to the specified angle relative to its initial orientation (0.0 arcsec). The absolute orientation of the initial reference point will be set via a real-time command. EVENT-FLAG (Restricted) = NO (default); YES When this parameter is specified as YES, the execution of the stored commands pertaining to the exposure will be contingent on positive authorization from ground personnel. The parameter should be specified on each exposure line to which it applies. Mode = SENSOR, (Restricted) Configuration = COSTAR The SENSOR mode is used to turn on the COSTAR mechanism position sensors without enabling any COSTAR mechanism motions. The exposure duration is the minimum time that the sensors will be powered and valid position telemetry will be available. Optional Parameters MECH (Restricted) = FOC, [FOS, GHRS] The FOC is the only COSTAR sensor which may be enabled. 315 Mode = FOS, Configuration = COSTAR (Restricted) The FOS mode is used to adjust the focus of the corrected FOS light path, and to adjust the tilt of the FOS M1 mirror along local orthogonal X and Y axes in order to center the pupil image on the M2 mirror. Optional Parameters FOCUS = 0.0 mm (defaults); range from –5.0 to +5.0 mm Moves the FOS M1 mirror axially to the specified position relative to its nominal zero position (0.0 mm). The absolute position of the nominal zero point will be set via a real-time command. X-TILT (Restricted) = 0.0 arcsec (default); range from -1200.0 to +1200.0 arcsec Tilts the FOC M1 mirror along the local X axis to the specified angle relative to its nominal zero orientation (0.0 arcsec). The absolute orientation of the nominal zero point will be set via a real-time command. Y-TILT (Restricted) = 0.0 arcsec (default); range from -1200.0 to +1200.0 arcsec Tilts the FOC M1 mirror along the local Y axis to the specified angle relative to its initial orientation (0.0 arcsec). The absolute orientation of the initial reference point will be set via a real-time command. EVENT-FLAG (Restricted) = NO (default); YES When this parameter is specified as YES, the execution of the stored commands pertaining to the exposure will be contingent on positive authorization from ground personnel. The parameter should be specified on each exposure line to which it applies. 316 Chapter 15: Corrective Optics Space Telescope Axial Replacement (Restricted) Mode = GHRS, Configuration = COSTAR (Restricted) The GHRS mode is used to adjust the focus of the corrected GHRS light path, and to adjust the tilt of the FOS M1 mirror along local orthogonal X and Y axes in order to center the pupil image on the M2 mirror. Optional Parameters FOCUS = 0.0 mm (defaults); range from –5.0 to +5.0 mm Moves the GHRS M1 mirror axially in a manner identical to the FOS mode. X-TILT (Restricted) = 0.0 arcsec (default); range from -1200.0 to +1200.0 arcsec Tilts the FOC M1 mirror along the local X axis to the specified angle relative to its nominal zero orientation (0.0 arcsec). The absolute orientation of the nominal zero point will be set via a real-time command. Y-TILT (Restricted) = 0.0 arcsec (default); range from -1200.0 to +1200.0 arcsec Tilts the FOC M1 mirror along the local Y axis to the specified angle relative to its initial orientation (0.0 arcsec). The absolute orientation of the initial reference point will be set via a real-time command. EVENT-FLAG (Restricted) = NO (default); YES When this parameter is specified as YES, the execution of the stored commands pertaining to the exposure will be contingent on positive authorization from ground personnel. The parameter should be specified on each exposure line to which it applies. CHAPTER 16: S/C Mode (Restricted) For an explanation of this engineering-only version, see Special Note to Engineering Version Users in Chapter 1: About This Document on page 1-3. In this chapter . . . Mode = DATA Configuration = S/C (Restricted) / 318 Mode = POINTING Configuration = S/C (Restricted) / 319 Spacecraft (S/C) mode exposures are designed to be used primarily by the engineering staff. S/C mode allows for two main capabilities which are not readily available in other operations modes: 1. It enables specification of telemetry requirements for science or engineering or both, and 2. It enables specification of a S/C pointing without the use of any science instrument (SI) or telemetry contacts. 317 318 Chapter 16: S/C Mode (Restricted) Mode = DATA Configuration = S/C (Restricted) This mode allows for the specification of the spacecraft telemetry requirements and optionally the spacecraft pointing. If there is no pointing requirement, the target should be specified as DARK. If telemetry is desired for an exposure using another configuration, the FORMAT exposure-level Special Requirement (see FORMAT [AN or FN or HN or PN] (Available but Unsupported)) should be used. Aperture or FOV NONE Specifies no pointing requirement. V1 Specifies the V1 axis as the reference position. Note: other positions can be specified using the POSition TARGet special requirement (see POSition TARGet <X-value>, <Y-value>). Special Requirements Special requirements should be used to specify real-time links and/or tape recorder operations (see Special Communications Requirements on page 7-141). • RT ANALYSIS should be used when a downlink is required. • FORMAT should be used if data is to go to the tape recorder. • REQuires UPLINK should be used when an uplink is required. • REQuires UPLINK and RT ANALYSIS should both be used when a downlink and an uplink are both necessary. 319 Mode = POINTING Configuration = S/C (Restricted) This mode supports the specification of the spacecraft pointing and control mode without any other requirements (i.e. telemetry or command). If the internal target DARK is used, no pointing requirement is imposed. In this case time is allocated in the planning process. The use of this time should be completely specified in the comments and text description of the observations. Aperture or FOV V1 All pointings are specified with respect to the origin of the V1 axis. To position the target at other places in the FOV use the POSition TARGet special requirement (see POSition TARGet <X-value>, <Y-value>). 320 Chapter 16: S/C Mode (Restricted) Index A ACQ-DIST Optional Parameter for FGS 247, 250 ACQTYPE Optional Parameter for STIS 204 Acquisition modes STIS 202 Acquisition uncertainty 75 AFTER – BY – TO – Special Requirement 131 AFTER – Special Requirement 131 ATD-GAIN Optional Parameter for WFPC2 185 AXIS1 and AXIS2 coordinate system for STIS 202 B BACKGROUND patterns 157 BEFORE – Special Requirement 131 BETWEEN – AND – Special Requirement 132 BINAXIS1, BINAXIS2 Optional Parameters for STIS 211, 216 Bright object constraints 53 BUFFER-TIME Optional Parameter for STIS 219 C CHECKBOX Optional Parameter for STIS 205 CLOCKS Optional Parameter for WFPC2 185 Continuous Viewing Zone (CVZ) 129 COUNT Optional Parameter for FGS 247 CR-SPLIT Optional Parameter for STIS 211 CR-SPLIT Optional Parameter for WFPC2 185 CR-TOLERANCE Optional Parameter for WFPC2 186 CVZ Special Requirement 129 D DIFFUSE-CENTER Optional Parameter for STIS 204 DITHER patterns 157 DROP TO GYRO Special Requirement 118 E END ORBIT Special Requirement 143 Ephemeris uncertainty 75 Examples, Phase II 18 Examples, target list blocks 85 EXPAND Special Requirement 144 Exposure, definition 90 F FES-TIME Optional Parameter for FGS 247 FGS ACQ-DIST Optional Parameter 247, 250 Aperture coordinate system 252 COUNT Optional Parameter 247 FES-TIME Optional Parameter 247 NULL Optional Parameter 246 POS mode 245 SCANS Optional Parameter 249 Spectral elements (table) 251 STEP-SIZE Optional Parameter 249 TRANS mode 248 G GAIN Optional Parameter for STIS 211 321 322 Index GROUP WITHIN Special Requirement 132 GSSS 42 Guiding Accuracies of guiding modes (table) 117 GUIDing TOLerance Special Requirement 118 Guiding-related Special requirements 117 Gyro Use of for guiding 118 I INT ACQ Special Requirement 135 L Longitude, orbital 84 LOW-SKY Special Requirement 144 M MAGNETO coordinates 71 MAXimum DURation Special Requirement 144 MINimum DURation Special Requirement 144 MOSAIC patterns 157 N NO SPLIT Special Requirement 146 NULL Optional Parameter for FGS 246 O Observing windows 76 ON HOLD Special Requirement 134 Orbital longitude 84 ORIENT – TO – FROM – Special Requirement 123 ORIENT – TO – Special Requirement 120 Orientation and separation between instruments (table) 127 Orientation of instruments relative to U3 (table) 126 Orientation Special Requirements 119 P P2PI Changes since previous version 5 Document design 5 Parallel observations Coordinated 102, 105 Limitations 102 Pure 102, 103 PARallel WITH Special Requirement 139, 154 PATTERN Special Requirement 154 Coordinate_Frame 158 Number_Of_Points 157 Pattern_Number 156 Pattern_Orient 159 Pattern_Purpose 157 Pattern_Type 156 Pattern_Type=LINE 156 Pattern_Type=SPIRAL 157 Point_Spacing 157 Pattern_Purpose: BACKGROUND 157 Pattern_Purpose: DITHER 157 Pattern_Purpose: MOSAIC 157 PCS MODE Fine Special Requirement 117 PCS MODE Gyro Special Requirement 118 PERIOD AND ZERO-PHASE Special Requirement 132 PGRAPHIC coordinates 69 Phase II Proposal Entries Abstract 14 Acq_Uncert 75 Alternate_Names 25 Aperture 96 Calibration_Justification 15 Comments 54, 56, 84, 100 Config 95 Coordinate_Source 45 Data_Distribution 16 Ephem_Uncert 75 Epoch 58 Equinox 45, 58 Exposure_Number 93 Flux 49–53, 56, 82–84 Generic target specifications 56 Generic_Targets 55 Investigators 14 Number_of_Iterations 98 323 Observing_Description 15 On_Hold_Comments 92 Opmode 96 Optional_Parameters 98 Parallax 48 Parallel_Pointing_Tolerance 14 Position 34 Position, solar system targets 65 Proper motion 48, 58 Proposal_Information 12, 13 Questions 15 Real_Time_Justification 15 RV_or_Z 47 Sp_Element 97 Special_Requirements 100 Target description 29, 55, 64 Target position, comet and asteroid 67 Target position, Level 1 66 Target position, Level 2 68 Target position, Level 3 75 Target position, MAGNETO 71 Target position, PGRAPHIC 69 Target position, POS_ANGLE 70 Target position, SATellite 73 Target position, TORUS 71 Target_Name 25, 55, 62, 93 Target_Number 25, 55, 61 Time_Per_Exposure 98 Visit_Comments 93 Visit_Number 91 Visit_Priority 91 Visit_Requirements 92 Wavelength 97 Window 76 Examples 18 General instructions 11 How to submit 9 Limited resources 19 Problems 18 Special targets 94 Template 20 PHASE Special Requirement 146 POS TARG Special Requirement 137 POS_ANGLE coordinates 70 Position 34 Equatorial coordinates 36 Guide Star Selection System 42 Offsets 39 Region of sky 41 Required accuracy 34 Special catalogs 44 Uncertain or unknown coordinates 44 R Radial Velocity 47 READ Optional Parameter for WFPC2 186 Redshift 47 REQuires EPHEMeris CORRection Special Requirement 142 REQuires UPLINK Special Requirement 141 RT ANALYSIS Special Requirement 141 S SAA CONTOUR Special Requirement 139 SAME ORIENT AS Special Requirement 129 SAME POS AS Special Requirement 138, 155 SATellite coordinates 73 SCANS Optional Parameter for FGS 249 SCHEDulability Special Requirement 130 SEQ NON-INT Special Requirement 146 SEQuence WITHIN Special Requirement 133 SHADOW Special Requirement 147 SIZEAXIS2 Optional Parameter for STIS 207, 212 Solar system standard targets 63 Special catalogs 44 Special Requirements Acquisition of targets 134 AFTER – 131 AFTER – BY – TO – 131 BEFORE – 131 BETWEEN – AND – 132 Communications-related 141 CVZ 129 Dates and times 113 DROP TO GYRO 118 END ORBIT 143 EXPAND 144 Exposure number, reference to 113 324 Index Exposure-level, definition 114 GROUP WITHIN 132 GUIDing TOLerance 118 Guiding-related 117 INT ACQ 135 LOW-SKY 144 MAXimum DURation 144 MINimum DURation 144 NO SPLIT 146 ON HOLD 134 ORIENT – TO – 120 ORIENT – TO – FROM – 123 Orientation examples 120 Orientation of target in aperture 119 PARallel WITH 139, 154 PATTERN: see PATTERN Special Requirement PCS MODE Fine 117 PCS MODE Gyro 118 PERIOD AND ZERO-PHASE 132 PHASE 146 POS TARG 137 Position of target 137 REQuires EPHEMeris CORRection 142 REQuires UPLINK 141 RT ANALYSIS 141 SAA CONTOUR 139 SAME ORIENT AS 129 SAME POS AS 138, 155 SCHEDulability 130 SEQ NON-INT 146 SEQuence WITHIN 133 SHADOW 147 Syntax and rules 112 Timing-related 143 Visit-level, definition 114 STEP-SIZE Optional Parameter for FGS 249 STIS Acquisition modes 202 Aperture coordinate system 232 Apertures, supported 234 AXIS1 and AXIS2 coordinate system 202 CCDFLAT internal target 229 Imaging modes 210 Internal calibration targets 227 Pattern illustrations 232 Spectroscopic modes 210 STIS/CCD ACCUM mode 210 ACQ mode 203 ACQ mode, apertures 204 ACQ/PEAK mode 206 ACQTYPE Optional Parameter 204 BINAXIS1, BINAXIS2 Optional Parameters 211 CHECKBOX Optional Parameter 205 CR-SPLIT Optional Parameter 211 DIFFUSE-CENTER Optional Parameter 204 GAIN Optional Parameter 211 SIZEAXIS2 Optional Parameter 207, 212 Time_Per_Exposure 214 STIS/FUV-MAMA ACCUM mode 215 TIME-TAG mode 218 STIS/MAMA BINAXIS1, BINAXIS2 Optional Parameters 216 STIS/NUV-MAMA ACCUM mode 215 TIME-TAG mode 218 TIME-TAG BUFFER-TIME Optional Parameter 219 WAVE internal target 227 Wavelengths, supported (table) 226 SUM Optional Parameter for WFPC2 187 T Target name 25 Catalog name 26 Common name 28 Galaxies and clusters of galaxies 27 Quasars and active galaxies 28 Special targets 29 Star clusters and nebulae 27 Stars 27 Uncataloged targets 28 Timing-related Special Requirements 131 325 TORUS coordinates 71 V Visit and Exposure Specifications 90 Visit, definition 90 W WFPC2 Aperture coordinate system 197 Apertures (table) 184 ATD-GAIN Optional Parameter 185 CLOCKS Optional Parameter 185 CR-SPLIT Optional Parameter 185 CR-TOLERANCE Optional Parameter 186 Exposure times, valid (table) 191 LRF 184 Quadrant filters 194 READ Optional Parameter 186 Spectral elements (table) 192 SUM Optional Parameter 187 Wood’s filters 194 Window 76 326 Index

HST Phase 2 Proposal Instructions for Cycle 10

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