ACTIVITY ID: FGS/OTA-01 ACTIVITY TITLE: Guide Star Acquisition Verification APPLICABLE SMOV REQUIREMENT: J.10.4.8.5 DESCRIPTION: Guide star pairs will be acquired in finelock by the FGSs. A pair of guide stars will be acquired by two FGSs, tracked in finelock for a few (~5) minutes, after which time the PCS will drop to gyros. The same pair will be reacquired in finelock and tracked for an additional ~5 minutes. This test will be repeated with a different FGS designated to acquire the primary guide star. Each of the three FGSs will in turn be designated to acquire a primary guide star. The total test will require 3 HST orbits, and possibly less if a suitable CVZ pointing can be utilized. This test occurs within the BEA following the release of HST from the orbiter. IMPLEMENTATION METHOD: Proposal DEPENDENCIES: Successful completion of J.10.4.8.4, the gyro-to-FHST alignment process. DURATION: 3 HST orbits, within BEA. DATA REQUIREMENTS: The data need to be downlinked, either in realtime or by recorder readout, within two hours. ANALYSES & RESULTS: COMMENTS: AUTHOR/TELEPHONE/EMAIL/DATE: Ed Nelan / 410-338-4992 / nelan@stsci.edu / 18-Jan-2000 ACTIVITY ID: FGS/OTA-02 ACTIVITY TITLE: Verification of Operational Calibrations APPLICABLE SMOV REQUIREMENT: J.10.4.7.2.1 DESCRIPTION: The distortions, plate scale, and FGS-FGS alignment for each FGS shall be measured by observing the standard astrometric star cluster M35, which is accessible to HST from September through May each year. The test for each FGS will be a single orbit visit. The telescope pointing, ORIENT, and selected target stars for each visit will be identical to the appropriate pre-SM3B baseline visit for the given FGS. In each visit approximately 25 stars distributed through out the FGS field of view will be observed in Position Mode, and their relative angular positions will be determined during post observation data analysis. These relative positions will be compared to the appropriate pre-SM3B baseline data set to allow for a measurement of any changes in the optical distortions and or plate scale in a given FGS. Furthermore, by using identical, astrometric guide stars in the pre and post SM3B visits, the FGS-FGS alignments can be assessed for changes. The S-curve morphology and amplitude in each FGS will be obtained by observing the standard star Upgren69 in Transfer Mode. These data will be compared to pre-SM3B baseline data. The test in each FGS will be a single orbit visit. If there are changes to the distortion, alignment, or S-curve morphology and amplitude that are sufficiently large to compromise the reliability of guide star acquisition and/or telescope pointing performance under FGS control, the appropriate contingency calibration proposal shall be executed. IMPLEMENTATION METHOD: Proposal DEPENDENCIES: For the pre-SM3B observations there are no dependencies. For the post-SM3B observations the guide star acquisition test must succeed (FGS/OTA-01). DURATION: 12 external HST orbits (6 pre-SM3B, 6 post-SM3B) DATA REQUIREMENTS: ANALYSES & RESULTS: COMMENTS: Note, these are non-BEA observations. AUTHOR/TELEPHONE/EMAIL/DATE: Ed Nelan / 410-338-4992 / nelan@stsci.edu / 18-Jan-2000 ACTIVITY ID: FGS/OTA-03 ACTIVITY TITLE: FGS MiniOFAD APPLICABLE SMOV REQUIREMENT: J.10.4.7.2.2 DESCRIPTION: If necessary, as indicated by the results of FGS/OTA-02, the optical field angle distortion (OFAD) will be re-calibrated for a given FGS. The appropriate onboard flight software tables and PDB shall be updated as necessary. The OFAD will be recalibrated in a given FGS by observing selected stars from the standard astrometric star cluster M35 at a variety of telescope pointings and ORIENTS. The apparent changes in the relative angular positions of the stars as function of telescope orientation and translation shall be used the recompute the OFAD in that FGS. For a given FGS, the operational OFAD calibration will require 5 HST orbits. IMPLEMENTATION METHOD: Proposal DEPENDENCIES: FGS/OTA-02 DURATION: 5 HST orbits per FGS. DATA REQUIREMENTS: ANALYSES & RESULTS: COMMENTS: Note that this is a contingency activity only. AUTHOR/TELEPHONE/EMAIL/DATE: Ed Nelan / 410-338-4992 / nelan@stsci.edu / 18-Jan-2000 ACTIVITY ID: FGS/OTA-04 ACTIVITY TITLE: FGS-to-FGS Alignment APPLICABLE SMOV REQUIREMENT: J.10.4.7.2.3 DESCRIPTION: If necessary, as indicated by the results of FGS/OTA-02, the FGS-FGS alignment calibration shall be performed and the appropriate alignment matrices will be computed. Onboard tables abd the PDB shall be updated with the new calibration parameters. The FGS-FGS alignment calibration for a given FGS shall be determined by observing, with that FGS, selected stars in the standard astrometric star cluster M35 in Position Mode with the telescope's V1 pointing and orient held fixed. The stars will be distributed across the FGS field of view. The alignment of this particular FGS with respect to the others will be determined by using specific, astrometric guide star pairs in the guiding FGSs. The calibration for a given FGS shall require 4 HST orbits. The V1 pointing and orientation will remain fixed, but different guide star pairs will be used for each orbit. These "lever arms" from the FGS being calibrated to the guide star positions will be used to determine the FGS-FGS alignment. IMPLEMENTATION METHOD: Proposal DEPENDENCIES: FGS/OTA-02 DURATION: 4 HST orbits per FGS. DATA REQUIREMENTS: ANALYSES & RESULTS: COMMENTS: Note that this is a contingency activity only. AUTHOR/TELEPHONE/EMAIL/DATE: Ed Nelan / 410-338-4992 / nelan@stsci.edu / 18-Jan-2000 ACTIVITY ID: FGS/OTA-05 ACTIVITY TITLE: FGS K-Factor Determination APPLICABLE SMOV REQUIREMENT: J.10.4.7.2.4 DESCRIPTION: If necessary, as indicated by the results of FGS/OTA-02, the S-curves in a given FGS will be obtained at 5 locations in the FOV. These data will be used to update the FGS commanding database so that appropriate K-factor values used for the acquisition and tracking of guide stars can be computed. The standard star Upgren69 will be observed at the standard "5 points of light" positions in the FGS (these correspond to the -45, -22, 0, +22, +45 degree azimuthal position along the FGS centerline). The S-curves will be obtained in both the F583W filter and the 2/3 PUPIL. The 2/3 PUPIL data will be used to recompute the optimal values of the guide star acquisition parameters K1X, K1Y, K3X, K3Y, KZ, and KB. These values will be used to update the FGS commanding database. IMPLEMENTATION METHOD: Proposal DEPENDENCIES: FGS/OTA-02 DURATION: 5 HST orbits per FGS. DATA REQUIREMENTS: ANALYSES & RESULTS: COMMENTS: Note that this is a contingency activity only. AUTHOR/TELEPHONE/EMAIL/DATE: Ed Nelan / 410-338-4992 / nelan@stsci.edu / 18-Jan-2000 ACTIVITY ID: FGS/OTA-06 ACTIVITY TITLE: FGS Jitter Test APPLICABLE SMOV REQUIREMENT: J.10.4.7.2.5 DESCRIPTION: The FGSs will be used to measure the jitter experience by HST during the operation of the NCS. The Astrometer FGS1r will be used to observe selected stars in both Position Mode and Transfer Mode. These measurements are to be obtained after SM3B, but both before and during NCS operation. The before/after data sets will be compared to determine the affect, if any, of the NCS on HST pointing performance and jitter characteristics. The test will consist of two identical single orbit visits, one to execute before NCS turn on (but after SM3B), and the second to execute while NCS is operating under steady state. IMPLEMENTATION METHOD: Proposal DEPENDENCIES: FGS/OTA-01 DURATION: 2 HST orbits, one to execute pre-NCS turn on, one to execute with NCS in steady state (cold). DATA REQUIREMENTS: ANALYSES & RESULTS: COMMENTS: AUTHOR/TELEPHONE/EMAIL/DATE: Ed Nelan / 410-338-4992 / nelan@stsci.edu / 18-Jan-2000 ACTIVITY ID: FGS/OTA-07 ACTIVITY TITLE: FGS Astrometer Calibration Verification APPLICABLE SMOV REQUIREMENT: J.10.4.7.3.1 DESCRIPTION: The photometric response, distortions, plate scale, and S-curve morphology and amplitude will be measured in the Astrometer FGS. These data will be used to recertify the Astrometer for scientific observations. The Astrometer FGS will be used to observe selected stars in Position Mode in the standard astrometric star cluster M35 to measure their relative angular positions. The data will be compared to an identical data set (same V1 pointing and telescope ORIENT) obtained before SM3B. If the changes in distortions and plate scale are within the astrometry error budget than the Astrometer will be certified to resume scientific observations in Position Mode. The Astrometer FGS will be used to observe the standard star Upgren69 in Transfer Mode with the F583W filter to evaluate the changes, if any, of the S-curve morphology and amplitude as a result of SM3B, by comparing the new observations to similar data acquired before SM3B. If the changes are sufficiently small, i.e., no greater than what is typically seen over comparable time periods, the Astrometer will be certified to resume scientific observations in Transfer Mode. IMPLEMENTATION METHOD: Proposal DEPENDENCIES: FGS/OTA-01 DURATION: These data will be acquired by the activities associated with FGS/OTA-02, so no additional HST orbits will be required. DATA REQUIREMENTS: ANALYSES & RESULTS: COMMENTS: For the post BEA observations. the execution of the guide star acquisition test must be successful. AUTHOR/TELEPHONE/EMAIL/DATE: Ed Nelan / 410-338-4992 / nelan@stsci.edu / 18-Jan-2000