ACTIVITY TITLE: COS Recovery from SAFE
ID: COS01
APPLICABLE SMOV REQUIREMENTS: L.10.4.1.1; L.10.4.2.1.2
DESCRIPTION: COS will be recovered from SAFE mode after release and
transitioned through instrument states Hold, Boot, Operate, and Observe preparatory to
commencement of subsequent SMOV activities. The transition from SAFE to Hold will
use the nominal safing recovery commanding and will be scheduled manually to occur
before to any other COS SMOV activities. Transitions to all states higher than Hold will
be scheduled automatically as needed for subsequent SMOV activities.
IMPLEMENTATION METHOD: Stored commanding
DEPENDENCIES: Successful COS AT/FT and HST release
DURATION:
0 Orbits (internal activity)
DATA REQUIREMENTS: 0 science bits to SSR.
ANALYSES & EXPECTED RESULTS: Engineering telemetry will be received from
all modes. The telemetry will be examined for all correct relay states, voltages,
temperatures, currents, and logical values, positions, and memory states.
COMMENTS: Proposal TBD (SPSS)
AUTHOR/telephone/email: T. Keyes (M.Reinhart) / 410-338-4975 / keyes@stsci.edu
DATE: 9/28/2007
ACTIVITY TITLE: COS Onboard Memory Check
ID: COS02
APPLICABLE SMOV REQUIREMENTS: L.10.4.1.4
DESCRIPTION: This activity is a test and verification of the COS dump of Control
Scetion (CS) memory capability. With the DIB and CS both in OPERATE, perform full
dumps of the CS’s EEPROM, PROM, and EXEC RAM. Then copy DIB data from DIB
RAM and DIB PROM to CS Buffer RAM and dump the portion of the CS Buffer RAM
containing the DIB data as normal science images. Next, with the FUV detector in its
OPERATE state, copy the DCE RAM to CS Buffer RAM and dump the portion of the
CS Buffer RAM containing the DCE data as a normal science image. (Note: The
remainder of CS Buffer RAM is checked in another proposal.)
IMPLEMENTATION METHOD: Stored commanding
DEPENDENCIES: COS 01 (COS Recovery from SAFE) completed prior to this
activity; the FUV detector must be in Operate to properly perform the DCE memory
dump test sequence. VDT depends upon successful completion of this activity.
DURATION: 1 orbit (internal)
DATA REQUIREMENTS: 3.83 MB
ANALYSES & EXPECTED RESULTS: Memory Dumps and telemetry data will be
produced. The memory dumps will be checked for proper format and large images will
be compared against images stored in the memory manager.
COMMENTS: Proposal 11353 – COS Dump Test and Verification of COS Memory
Loads. This proposal requires Special Commanding to execute.
AUTHOR/telephone/email: T. Keyes (A. Welty) / 410-338-4975 / keyes@stsci.edu
DATE: 9/28/2007
ACTIVITY TITLE: COS Science Data Buffer Check
ID: COS03
APPLICABLE SMOV REQUIREMENTS: L.10.4.1.5
DESCRIPTION: The COS Science Buffer RAM is checked for bit flips during SAA
passages. This is followed by a Control Section (CS) self-test consisting of
writing/reading a specified bit pattern from each memory location in Buffer RAM and a
similar test for DIB RAM. The DIB must be placed in BOOT mode for its self-test.
The CS Buffer RAM self-test and the bit flip tests are all done with the CS in Operate.
Using the set buffer memory macro, write zeros into CS Buffer RAM prior to passage
into the SAA and then dump buffer memory to SSR after exit from the SAA to check for
bit flips. This Buffer RAM check should be executed several times. Then use the CS self
test macro to conduct a pattern test of CS Buffer RAM and check the memory fail
counter after the test has completed. Repeat for a similar DIB self test. The DIB will need
to be in its BOOT mode for its self-test.
IMPLEMENTATION METHOD: Stored commanding
DEPENDENCIES: COS 02 (COS Onboard Memory Check) should be performed prior
to this activity.
DURATION: 7 orbits (internal) (assumes Buffer RAM check performed six times)
DATA REQUIREMENTS: 108 MB (one 18 MB buffer per Buffer RAM check)
ANALYSES & EXPECTED RESULTS: Comparisons of the memory dumps and
exposures will be done with the expected images and against each other. This will allow
quantification of the effects of SAA on memory, and become a driver for whether science
data can be left in the buffer during SAA passages while waiting to be dumped.
COMMENTS: Proposal 11354 – COS Science Data Buffer Checks/Self-Tests for CS
Buffer RAM and DIB RAM. This proposal requires Special Commanding to execute and
the DIB to be in BOOT mode for the DIB self-test. For both the CS and DIB self-tests, a
memory monitor must be set to check the results of the tests. The CS tests are done in
OPERATE so that CS paging is enabled and all 18 megabytes of memory are available
for testing.
AUTHOR/telephone/email: T. Keyes (A. Welty) / 410-338-4975 / keyes@stsci.edu
DATE: 9/28/2007
ACTIVITY TITLE: COS NUV Detector Signal Processing Check and Initial High
Voltage Turn On & Ramp Up
ID: COS04
APPLICABLE SMOV REQUIREMENTS: L.10.4.2.1.2, L.10.4.2.1.6, L.10.4.2.2.2
DESCRIPTION: After a signal processing check with only the detector low voltage on,
the high voltage on the COS NUV MAMA detector will be turned on for the first time
and then ramped to its nominal voltage. The ramp-up will be done slowly, and in multiple
steps:
Part 1. The COS NUV is transitioned to its low voltage state, with the charge amplifier
threshold set to the nominal value, 0.48V. Wait for 30 telemetry samples of OR counts.
Then set the charge amplifier threshold to 0.28V and wait for another 30 samples of OR
counts. Without the HV, no counts are expected at 0.48V, but 'noise' counts are expected
at 0.28V. Next, return the NUV detector to its Hold state. Finally, set COS event flag 2,
which will inhibit further NUV commanding until it is cleared.
Part 2. Transition the NUV to its low voltage state and perform a slow, partial ramp-up of
the MCP high voltage. The ramp-up will be commanded in four phases, stopping at
plateaus of -500V, -1000V, -1500V, and -1750V (300V short of the nominal -2050V).
Each phase will proceed in -50V steps, with a 30 second wait after each step. There will
be a four minute wait at each plateau, during with OR counts will be monitored. Then the
PC voltage will be ramped to -50V. Next, the software global monitor will be
commanded to look at X, Y, Z, W, OR, EV, and VE counts for one minute each, all
during a dark time-tag exposure. Then return the NUV detector to its Hold state. Finally,
set COS event flag 2, which will inhibit further NUV commanding until it is cleared.
Part 3. This part follows part 2 by at least 1 day. This part repeats the part 2 LV and HV
ramp-up commanding, and follows it with three more MCP plateaus (-1850V, -1950V, &
-2050V) and a final ramp-up of the PC voltage to -800V, thus reaching the nominal
operating state. At the end the high voltages are ramped back down again and HV is
turned off until ground analysis is completed.
IMPLEMENTATION METHOD: Stored commanding and real-time commanding
DEPENDENCIES: To be run only after the internal pressure is less than 20 micro-Torr
for 12 consecutive hours (CARD item), and after the low voltage checkout of the detector
is completed.
DURATION: 3 orbits, with one day for analysis between each.
DATA REQUIREMENTS: 4 dark time-tag exposures; probably <1 Mbtye.
ANALYSES & EXPECTED RESULTS: This activity will verify the normal
operation of the NUV detector. Dark exposures, along with engineering telemetry, must
be examined after the partial ramp up in order to verify the proper operation of the
detector before continuing. Exposures and telemetry must be examined again after the
full ramp up before subsequent HV operations occur; this will take at least one day.
COMMENTS: Proposal number 11355. This proposal requires Special Commanding to
execute.
AUTHOR/telephone/email: David Sahnow/410-516-8503/sahnow@pha.jhu.edu (Alan
Welty)
DATE: 10/4/07
ACTIVITY TITLE: COS NUV Detector Dark Count Measurement
ID: COS05
APPLICABLE SMOV REQUIREMENTS: L.10.4.2.3.1; L.10.4.2.1.8
DESCRIPTION: Measure the NUV detector dark rate by taking long science exposures
with no light on the detector.
IMPLEMENTATION METHOD: Stored commanding.
DEPENDENCIES: To be run no less than 2 days after the NUV Detector Initial Turn
On (COS04).
DURATION: 6500 seconds per exposure.
DATA REQUIREMENTS: 10 dark (internal) time-tag exposures; < 2 Mbytes.
ANALYSES & EXPECTED RESULTS: Verifies TIME-TAG operation. The
detector dark rate and spatial distribution of counts will be compared to pre-launch data
in order to verify the nominal operation of the detector, and for use in the calibration
pipeline. Variations of count rate as a function of orbital position may be analyzed to find
dependence of dark rate on proximity to the SAA.
COMMENTS:
AUTHOR/telephone/email: David Sahnow/410-516-8503/sahnow@pha.jhu.edu
DATE: 9/27/07
ACTIVITY TITLE: COS NUV Detector Internal Functionality and Operation
ID: COS06
APPLICABLE SMOV REQUIREMENTS: L.10.4.2.1.8; L.10.4.2.2.2; L.10.4.2.3.1
DESCRIPTION: Verify the functionality and operation of the NUV detector using
internal sources. Obtain several science exposures in TIME-TAG using both the
DEUTERIUM and Pt/Ne lamps. A single DEUTERIUM exposure of 60 seconds should
be taken to verify the operation of the lamp. This should be followed by multiple 60
second exposures of the PtNe lamp in order to obtain an initial, coarse characterization of
the OSM drift. The grating and central wavelength are TBD, but they should be the same
as used in COS12, and ideally should involve a movement of the OSM so that OSM drift
occurs.
This test can be done before the optical alignment of the instrument.
IMPLEMENTATION METHOD: Stored commanding.
DEPENDENCIES: To be run no less than 2 days after the NUV Detector Initial Turn
On (COS04) and only after the internal pressure is less than 10 micro-Torr for 12
consecutive hours.
DURATION: 1 internal orbit.
DATA REQUIREMENTS: < 1 MByte
ANALYSES & EXPECTED RESULTS: The science images will be compared with
similar images taken on the ground before launch. The locations of the spectra will be
used to determine the initial locations of the spectra in the cross-dispersion direction so
that modifications can be made to patchable constants used for peak ups. The OSM drift
will be compared to thermal vac data to determine if its characteristics have changed.
COMMENTS:
AUTHOR/telephone/email: David Sahnow/410-516-8503/sahnow@pha.jhu.edu
DATE: 10/4/07
ACTIVITY TITLE: COS NUV Detector Fold Test
ID: COS07
APPLICABLE SMOV REQUIREMENTS: L.10.4.2.3.1; L.10.4.2.3.8
DESCRIPTION: The NUV detector fold test is a diagnostic of the proper performance
of the MAMA detector. The count rate as a function of fold number, or pulse size will be
measured using data from a science exposure. A brief description of the steps involved is
included here.
Set the Software Global Monitor to a value that is large enough to permit a count
rate spike when the lamp is turned on. Begin a 2300-second deuterium lamp exposure at
MEDIUM current with OSM1 at the NCM1FLAT position, and OSM2 at G185M, with a
central wavelength of 1850 Angstroms. During the exposure, each fold should be enabled
separately and counter samples for the X, Y, Z, W, VE, EV, and OR counters should also
be collected.
IMPLEMENTATION METHOD: Stored commanding
DEPENDENCIES: To be run no less than 2 days after NUV Detector Initial HV turn on
and ramp up (COS04)
DURATION: 1 internal orbit
DATA REQUIREMENTS: 1 2300-second time-tag exposure. Total volume is ~4
Mbytes.
ANALYSES & EXPECTED RESULTS: This activity will help verify the normal
operation of the NUV detector. The science exposure will be used to construct a
histogram of the number of counts for each fold. Variations in this histogram of more
than 20% from pre-launch data will require further analysis of the detector performance.
COMMENTS: This proposal requires Special Commanding to execute.
AUTHOR/telephone/email: David Sahnow/410-516-8503/sahnow@pha.jhu.edu (Alan
Welty)
DATE: 9/27/07
ACTIVITY TITLE: COS OTA to FGS Alignment (NUV)
ID: COS08
APPLICABLE SMOV REQUIREMENTS: L.10.4.2.3.2
DESCRIPTION: In order to determine the location of the COS reference frame with
respect to the FGS reference frames, NUV MIRRORA images will be obtained of an
astrometric target and field. Astrometric guide stars and targets must be employed for
this activity. Images will be obtained at the initial pointing and at positions offset in V2
and in V3. Starting with the original blind pointing, obtain MIRRORA image exposures
in a 5x5 POS-TARG grid centered on initial pointing; repeat the image sequence at two
bracketing focus positions in same visit. Following completion of third pattern, perform
5x5 ACQ/SEARCH target acquisition and obtain one TIME-TAG MIRRORA image
exposure for each of the three focus positions used previously. Analyze imagery, adjust
nominal focus via patchable constant uplinked with subsequent SMS; update aperture
locations via modified SIAF file uplinked with subsequent SMS. Use updated focus and
aperture location as input for COS 09 (note the SIAF update is not a prerequisite for COS
09 to proceed, but the focus update is).
IMPLEMENTATION METHOD: Stored commanding. Updates to the OSM1 focus
position made via patchable constants uploaded on subsequent SMS; differential focus
adjustment during data acquisition visit performed via stored commanding.
DEPENDENCIES: COS06 (COS NUV Detector Functional) and BEA Complete.
DURATION: 5 orbits (all external).
DATA REQUIREMENTS: Total volume of ~153 Mbytes. 75 ACCUM mode image
exposures (150 Mbytes) plus 3 TIME-TAG exposures (~3 Mbytes).
ANALYSES & EXPECTED RESULTS: Science exposures data will be produced
and used for all analysis. Analyze the PSA imagery to determine accurate (V2,V3)
position of aperture center and its rotation angle with respect to the FGS reference frame.
The rotation matrices used in the NSSC-1 for target acquisition slews and the aperture
locations in the aperture file (SIAF) in the PDB will be updated accordingly. Changes to
all COS apertures will be determined analytically from the results obtained for the PSA.
Analyze image characteristics to inform focus adjustments required for COS09, as well.
Perform initial coarse focus update on basis of imagery – requires uplink of patchable
constants in subsequent SMS. After updates, proceed to COS09.
COMMENTS: Proposal TBD
AUTHOR/telephone/email: T. Keyes (G. Hartig) / 410-338-4975 / keyes@stsci.edu
DATE: 10/4/2007
ACTIVITY TITLE: COS NUV Optical Alignment and Focus
ID: COS09
APPLICABLE SMOV REQUIREMENTS: L.10.4.2.3.3; L10.4.2.3.4; L.10.4.2.1.8
DESCRIPTION: After the initial coarse focus update determined in COS08, a sequence
of 11-15 NUV MIRRORA exposures will be made to perform a fine-focus sweep
through nominal focus. The same astrometric target and, if possible, the same guide stars
from COS08 will be used. A target_offset pointing will be employed to insure target
centering and, if the ACQ/SEARCH test in COS08 is successful, an ACQ/SEARCH will
be performed followed by the focus sweep set of images. .
After the data are analyzed, a patchable constant update of focus will be uplinked with
the subsequent SMS. Additionally, a new SIAF aperture location and physical aperture
mechanism position update will be made to correct for coma. Expediting of these SMSbased updates will be requested as this process must be repeated twice more in this
activity and all subsequent COS activity is dependent upon these updates.
After the final focus adjustment a series of MIRRORA exposures with the aperture
mechanism stepped in a fine raster will be obtained. After this series of 26 exposures
across the field in X and in Y is obtained (13 in each coordinate), a final verification set
of images for 5 combined aperture mechanism offsets and compensating POS-TARG
displacements will be obtained to characterize off-axis optical image characteristics
Some observations will be taken in ACCUM mode.
IMPLEMENTATION METHOD: Stored commanding and real-time uplinks
DEPENDENCIES: COS08 (COS to FGS Alignment – NUV) – includes initial coarse
focus measurements
DURATION: 9 Orbits (external) first three visits EACH require 2 orbits followed by 2
day analysis periods and up to 2-week waits for new SIAF delivery to be available onorbit; final 2 visits can be executed in close proximity following the last uplink and
require 2 orbits and 1 orbit, respectively. Image quality verification based upon last two
visits must precede all subsequent COS activity. Two days will be required for the final
verification.
DATA REQUIREMENTS: 76 images will be acquired in the program. On the
assumption that ACCUM mode will be employed, ~150 Mbytes of data will be produced.
ANALYSES & EXPECTED RESULTS: Science exposure data will be produced,
downlinked, and analyzed. The data will be analyzed by IDL software. The data should
be available for analysis within 24 hours of the observations to facilitate rapid delivery of
the revised SIAF file. Verifies ACCUM mode.
COMMENTS: Proposal TBD
AUTHOR/telephone/email: T. Keyes (G. Hartig) / 410-338-4975 / keyes@stsci.edu
DATE: 10/4/2007
ACTIVITY TITLE: COS Internal NUV Wavelength Measurement
ID: COS10
APPLICABLE SMOV REQUIREMENTS: L.10.4.2.3.1
DESCRIPTION: After completion of NUV optical alignment and focus, an initial
series of internal wavelength calibration exposures will be obtained with each grating and
central wavelength combination at the default FP-POS. One central wavelength position
with each grating will be observed at all FP-POS. Additionally, TA1 images of the
default wavelength calibration lamp with both MIRROR settings will be obtained to
establish performance characteristics.
In a separate visit that is not in the critical path to establishing the operational science
wavelength scale, wavelength calibration spectra with the alternate PtNe lamp (lamp 2)
will be obtained with each grating at one central wavelength and FP-POS position. The
lamp 2 visit can conveniently be executed during the period between visit 1 of the present
activity (COS 10) and COS 15 while SIAF and OSM position updates are being
implemented. The entire activity will be conducted as a series of internal exposures
IMPLEMENTATION METHOD: Stored commanding
DEPENDENCIES: COS09 (COS NUV Optics Alignment and Focus) required prior to
execution of visit 1. Visit 2 should execute after visit 1 and, if possible, prior to COS15.
DURATION: 6 orbits (internal)
DATA REQUIREMENTS: Visit 1 contains 9 exposures totaling ~100 Mbytes; Visit 2
will produce ~70 Mbytes. .
ANALYSES & EXPECTED RESULTS: Science exposure data will be produced.
Dispersion relations will be obtained for each spectral element, central wavelength, and
FP-POS for lamp 1 (default lamp). Lamp output and imaging performance
characteristics will be obtained from the TA1 imagery and lamp performance
characteristics will be established for the alternate lamp (lamp 2).
COMMENTS: Proposal TBD
AUTHOR/telephone/email: T. Keyes / 410-338-4975 / keyes@stsci.edu
DATE: 10/3/2007
ACTIVITY TITLE: COS NUV Imaging Acquisition Algorithm Verification
ID: COS11
APPLICABLE SMOV REQUIREMENTS: L.10.4.2.3.5.1; L.10.4.2.1.8; L.10.4.2.3.13
DESCRIPTION:
Verify the ability of the COS FSW to place an isolated point source at the center of the
aperture, both for the BOA and PSA, and for MIRRORA and MIRRORB.
Demonstration of this capability is preceded by a determination of the location of the
PSA. The various options for target centering should be exercised and shown to work
properly. This test is for acquisitions in imaging mode only. Acquisitions using
dispersed light are tested in separate SMOV activities (COS12 for NUV and COS28 for
FUV).
HOW THE ACTIVITY IS BEST IMPLEMENTED: Stored commanding
DEPENDENCIES:
This activity should follow COS09, “Internal NUV Optics Alignment and Focus.”
DURATION: 4 orbits.
DATA REQUIREMENTS:
The total data quantity is small. Approximately 10 acquisitions will occur. Each image
is 345 x 816 pixels, and there are two such images per acquisition. There is an additional
200 x 660 pixel image of the aperture taken for each acquisition. Thus each acquisition
produces about 700k pixels’ worth of data, or 7 Mbytes for the program. The data
quantity of each is not certain because acquisition images are taken in TIME-TAG mode.
ANALYSES & EXPECTED RESULTS:
The first result is verification that the PSA is physically located at the place inferred from
the initial Pt-Ne exposure. Second, successful centering of a point source within both the
PSA and BOA is verified, using all the centering options available. This activity does not
test the precision and accuracy of imaging acquisitions except to verify that the centering
error does not exceed a given threshold, viz. 0.1 arcsec. The accuracy of acquisitions will
be established over time through statistical analysis of many acquisitions. Third,
MIRRORB will be used in combination with the PSA to verify that it provides good
acquisitions. Verifies routine NUV detector subarray readout.
From the downlinked image, as well as using data from the acquisition sequence that is in
the data headers, the accuracy of the target centering process will be assessed. The initial
requirement for centering is 0.1 arcsec.
This test should precede COS12 and COS28 (acquisitions in dispersed light).
COMMENTS:
Verifying the location of the PSA could be done by observing a region of nebulosity so
that there is light filling the aperture. Note that it is not necessary that light completely or
uniformly fill the aperture; we just need to be able to see where the edges are for enough
of the aperture to be able to define its center. The source needs to emit in the ultraviolet,
at wavelengths COS/NUV is sensitive to, and to have a suitable flux level to avoid either
excessive count rates or too feeble a source.
Assuming that such a region of nebulosity can be found (perhaps in Orion, or perhaps by
examining data from Galex), we should also execute a target acquisition in that region to
test the case of a star against a bright background. We also need to test the case of an
isolated star with essentially no background and the case of a star with fainter nearby
objects that also fall in the aperture. Therefore this activity comprises four separate
visits.
Visit 1 will include:
•
Acquisition of an isolated point source with the PSA and MIRRORA. This
portion should start with an ACQ/SEARCH and SCAN-SIZE=3 to ensure a
successful acquisition even if the initial alignment is imperfect.
•
A small motion of the object away from the aperture center, followed by reacquisition of the same object using ACQ/IMAGE with MIRRORB and the PSA.
•
Re-acquisition of the same object with ACQ/IMAGE, MIRRORA and the PSA in
order to compare the results from MIRRORB to those from MIRRORA to ensure
they are not significantly different.
•
Displacement of the object in the aperture, followed by re-acquisition of the same
object with ACQ/IMAGE, the BOA and MIRRORA, again to see if there is a
systematic difference when an object is acquired in the different apertures.
Visit 2 includes:
•
Acquisition of a point source located in nebulosity, using ACQ/SEARCH, SCANSIZE=3, etc.
•
A small motion of the object away from the aperture center, followed by reacquisitions of the same object, each using a different centering algorithm.
Visit 3 includes:
•
Acquisition of an isolated point source with the BOA and MIRRORA.
•
Reacquisition of the same object with the BOA and MIRRORB.
Visit 4 includes:
•
Acquisition of a point source located about 1 arcsec away from another point
source that is roughly a magnitude fainter, using the procedure in Visit 1, except
that the BOA need not be used.
Each of these should take approximately one orbit each.
AUTHOR/telephone/email:
D. Soderblom/STScI/410-338-4543/drs
2007-10-04
ACTIVITY TITLE: COS NUV Dispersed-light Acquisition Algorithm Verification
ID: COS12
APPLICABLE SMOV REQUIREMENTS: L.10.4.2.3.5.2
DESCRIPTION:
Verify the ability of the COS FSW to place an isolated point source at the center of the
aperture, both for the BOA and PSA, using dispersed light from the object using an NUV
grating. The various options for target centering should be exercised and shown to work
properly. This test is for acquisitions in dispersed-light mode only. Acquisitions using
imaging are tested in a separate SMOV activity (COS 11). FUV dispersed-light
acquisitions are tested in COS 28.
HOW THE ACTIVITY IS BEST IMPLEMENTED: Stored commanding
DEPENDENCIES:
This activity should follow COS11, “COS NUV Imaging Acquisition Algorithm
Verification.”
DURATION: 3 orbits.
DATA REQUIREMENTS:
Only very small quantities of data (<1 Mbyte) are produced for downlinking because
only header information is provided.
ANALYSES & EXPECTED RESULTS:
Successful centering of a point source within both the PSA and BOA is verified, using all
the centering options available (CENTER=FLUX-WT; FLUX-WT-FLR; and
BRIGHTEST). This activity verifies that the centering error does not exceed a given
threshold, viz. 0.1 arcsec.
This test should precede COS28 (FUV acquisitions in dispersed light).
COMMENTS:
It is sufficient to carry out this test with only one of the NUV gratings because it is the
overall algorithm being tested, and it should work in the same way for any of the
gratings. To be specific, grating G225M will be used set at 2268 A.
This activity comprises two separate visits. Visit 1 will include:
•
Acquisition of an isolated point source with the PSA. This portion should start
with an ACQ/SEARCH and SCAN-SIZE=3 to ensure a successful acquisition
even if the initial alignment is imperfect. The default STEP-SIZE of 1.767 arcsec
should be used. The default CENTER option (FLUX-WT) should be used.
•
Use of ACQ/IMAGE to obtain a confirming image to test the accuracy of the
initial acquisition.
•
Use of COS/NUV TIME-TAG mode to obtain a spectrum to verify locations of
the three stripes. Only modest signal-to-noise is needed and so the exposure can
be short.
•
Displacement of the object from aperture center, followed by ACQ/SEARCH
again. The SCAN-SIZE can be reduced to 2, and CENTER=FLUX-WT-FLR
should be tried. This is followed by ACQ/IMAGE to again check the precision of
centering.
•
Repetition of the previous step using CENTER=BRIGHTEST.
•
Use of ACQ/PEAKXD to peak-up the spectrum in the cross-dispersion direction.
The grating and wavelength are the same as for ACQ/SEARCH, and
STRIPE=DEF is to be used. Other default parameters are used as well.
•
Use of ACQ/PEAKD to center the spectrum in the along-dispersion direction.
•
Finally, an ACQ/IMAGE should again be performed to determine the relative
centering precision of dispersed-light acquisitions versus those in integrated light.
Visit 1 is estimated to require 2 orbits.
Visit 2 is similar to Visit 1 but will use G230L to test the STRIPE option. Because low
dispersion is used, a fainter target is required. In this case a more limited test will be
performed using only the default CENTER option. Visit 2 includes:
•
Acquisition of an isolated point source with the PSA. This portion should start
with an ACQ/SEARCH and SCAN-SIZE=3 to ensure a successful acquisition
even if the initial alignment is imperfect. The default STEP-SIZE of 1.767 arcsec
should be used. The default CENTER option (FLUX-WT) should be used.
•
Use of ACQ/IMAGE to obtain a confirming image to test the accuracy of the
initial acquisition.
•
Use of COS/NUV TIME-TAG mode to obtain a spectrum to verify locations of
the three stripes. Only modest signal-to-noise is needed and so the exposure can
be short.
•
Use of ACQ/PEAKXD to peak-up the spectrum in the cross-dispersion direction.
The grating and wavelength are the same as for ACQ/SEARCH, and
STRIPE=DEF is to be used.
•
Use of ACQ/PEAKD to center the spectrum in the along-dispersion direction.
•
Finally, an ACQ/IMAGE should again be performed to determine the relative
centering precision of dispersed-light acquisitions versus those in integrated light.
Visit 2 should be achieveable in 1 orbit.
Visit 3 repeats everything in Visit 2 except the BOA is used on a brighter star and
G225M is used. Again, 1 orbit is needed.
The target or targets can likely be chosen from the astrometric field in M35. Use of the
ETC can enable an optimum target to be chosen based on spectral type (from optical
colors).
AUTHOR/telephone/email:
D. Soderblom/STScI/410-338-4543/drs
2007-10-04
ACTIVITY TITLE: COS NUV Imaging Performance Verification
ID: COS13
APPLICABLE SMOV REQUIREMENTS: L.10.4.2.3.6.1, L.10.4.2.3.6.2,
L.10.4.2.3.6.3, L.10.4.2.3.13
DESCRIPTION:
This activity is designed to verify that the COS/NUV imaging mode performs properly,
that the achieved PSF is satisfactory, determine plate scale, and evaluate throughput for
imaging with both MIRRORA and MIRRORB. To do this, an isolated point source will
be acquired, centered in the PSA, and then moved to various positions in the PSA in a
grid pattern. In addition, imaging will be obtained for a point source observed with both
the PSA and BOA to determine the relative image quality of the BOA. The source will
likewise be moved in a grid pattern in the BOA.
The last part of this activity tests the stability of the image by continuously observing a
point source over several orbits.
HOW THE ACTIVITY IS BEST IMPLEMENTED: Stored commanding
DEPENDENCIES:
This activity should follow COS11, “COS NUV Imaging Acquisition Algorithm
Verification.”
DURATION: approximately 6 Orbits (external) – choice of target needed to refine
DATA REQUIREMENTS:
Each acquisition produces three images: one is 200 x 660 and two are 345 x 816, for a
total of 700k pixels per acquisition in TIME-TAG mode. Approximately 12 acquisitions
will be done in this program, for a total data quantity of about 8 Mbytes.
ANALYSES & EXPECTED RESULTS:
First, this activity verifies that the PSF of COS/NUV in imaging mode meets
specifications and is comparable to what has been achieved in ground tests prior to flight
(i.e., encircled energy versus radius); both MIRRORA and MIRRORB imaging will be
evaluated. Second, this activity verifies the optical performance of the BOA relative to
the PSA. Pre-flight tests show that the BOA degrades the image quality of COS, and that
this is believed to be due to a slight wedge shape to the neutral density filter that is part of
the BOA. Plate-scale and throughput will be determined for MIRRORA and MIRRORB
with the PSA and with MIRRORA for the BOA. Lastly, the jitter and stability of the
image will be determined.
From the downlinked images, as well as using data from the acquisition sequence that is
in the data headers, the accuracy of the initial target centering process will be assessed.
The ability to move a source within the PSA will also be tested, and the quality of the
image confirmed at each location. This will also be done for the BOA. In the last part of
the activity, images obtained in TIME-TAG mode will be analyzed to track the motion of
the image over time.
COMMENTS:
Analysis of the images as the point source is displaced further from the aperture center
will establish the degree of light in the wings of the PSF at the PSA. This test will
require good signal-to-noise (probably about 100,000 detected photons) to yield reliable
results, but that should be achievable in a modest time with a source of suitable
brightness. The source should not be so bright, however, that non-linearity corrections
exceed about 1%. The known stars in M35 used by other instruments in the past for
astrometric purposes can likely be used in this test. The earliest spectral type stars in
M35 are about A0 and have V = 8, much too bright for COS, but by working down the
main sequence it should be possible to select targets with moderate near-UV fluxes
because good optical photometry exists for M35, even if there is not specifically UV
photometry. MIRRORB will be evaluated only at nominal aperture center.
The grid for the PSA should be on 0.25 arcsec centers on both axes (along dispersion and
cross-dispersion) plus other points 0.5 arcsec apart in the quadrants, or 45 pointings total.
For the BOA the grid can be on 0.5 arcsec centers, or 29 pointings.
Sources for this activity are best if located in the CVZ so that continuous observations
can be obtained efficiently. At least one source with ultraviolet photometry is required.
The jitter test should be done only well after the last OSM motion has occurred (by one
full orbit or more) so that any motions seen can be reliably attributed to the spacecraft.
AUTHOR/telephone/email:
D. Soderblom/STScI/410-338-4543/drs
2007-10-04
ACTIVITY TITLE: COS NUV Internal/External Wavelength Scales
ID: COS14
APPLICABLE SMOV REQUIREMENTS: L.10.4.2.3.7.1; L.10.4.2.1.8
DESCRIPTION: Observe an external radial velocity standard target (preferably, though
not required, in CVZ) in TIME-TAG (FLASH=YES) mode with all grating and central
wavelength combinations. The purpose is to obtain zero-point offsets for the wavelength
scale (internal wavecal lamp scale to external standard wavelength scale) for all central
wavelengths. Following this determination, adjustments of the nominal science target
spectral range for each grating and central wavelength combination will be made via
SMS patchable constant for nominal OSM2 positions corresponding to each central
wavelength. Subsequent to this modification of the wavelength scale (and its verification
in COS 15), science-related operations and EROs can commence.
IMPLEMENTATION METHOD: Stored commanding.
DEPENDENCIES: Execute after COS10 (Internal NUV Wavelength Calibration);
following analysis, update OSM position settings for each central wavelength via SMS
patchable constant; COS15 is executed after these updates.
DURATION: 7 orbits (external); CVZ preferred – not required.
DATA REQUIREMENTS: ~350 Mbytes (27 exposures).
ANALYSES & EXPECTED RESULTS: Science exposure data will be produced.
Determination of wavelength scale offsets between the internal wavecal lamps and the
external well-centered science target will be made for each grating and central
wavelength combination. The actual observed full spectral range will be determined and
compared with desired spectral range. An update of the onboard correspondence of
OSM2 hardware position and central wavelengths will be made and uplinked via SMS
patchable constant. After this change COS 15 will be executed to confirm results.
Activity also verifies TAGFLASH mode for (FLASH=YES) for NUV. Some longer
exposures will also be used to evaluate OSM drifts.
COMMENTS: Proposal TBD.
AUTHOR/telephone/email: T. Keyes / 410-338-4975 / keyes@stsci.edu
DATE: 9/27/2007
ACTIVITY TITLE: COS Internal NUV Wavelength Verification
ID: COS15
APPLICABLE SMOV REQUIREMENTS: L10.4.2.3.7.1
DESCRIPTION: Subsequent to the uplink of the OSM2 position updates derived from
the determination of the wavelength-scale zero points and desired spectral ranges for each
grating in activity in COS 14, an internal wavelength calibration spectrum using the
default PtNe lamp (lamp 1) with each NUV grating at each central wavelength setting
and each FP-POS position will be obtained for verification purposes. The entire activity
will be conducted as a series of internal exposures. This verification is required prior to
the enabling of COS ERO and science operations. Exposures following grating changes
will require several repetitions to avoid mechanism drifts.
IMPLEMENTATION METHOD: Stored commanding.
DEPENDENCIES: Execute after zero-points and wavelength ranges are established for
external sources in COS14
DURATION: 10 orbits (internal)
DATA REQUIREMENTS: The entire program will produce about 100 Mbytes of data,
however the program will likely be executed in 10 separate equally sized visits each
producing 10-12 Mbytes of data to the SSR.
ANALYSES & EXPECTED RESULTS: Science exposure data will be produced.
Dispersion relations will be obtained for each spectral element, central wavelength, and
FP-POS for lamp 1 (default lamp). The repeated exposures will be evaluated to assess
mechanism drifts.
COMMENTS: Proposal TBD
AUTHOR/telephone/email: T. Keyes / 410-338-4975 / keyes@stsci.edu
DATE: 10/3/2007
ACTIVITY TITLE: COS NUV External Spectroscopic Performance – Part 1
ID: COS16
APPLICABLE SMOV REQUIREMENTS: L.10.4.2.3.7.2; L.10.4.2.3.13; L.10.4.2.1.8
DESCRIPTION: This activity measures absorption line spectral resolution at one
central wavelength with each NUV grating for both PSA and BOA apertures and
evaluates spectral resolution at offset pointings characteristic of routine COS observation.
Perform precision-centering target acquisition for an external target with sharp, welldefined absorption lines. Obtain moderately high S/N (~50 counting statistics if possible)
observations at one central wavelength setting for each NUV grating with BOA and with
PSA. Using the PSA repeat the sequence of observations at each of four additional POSTARG pointings to form a diamond whose vertices are displaced 0.25 arcsec in either X
or Y from the initial pointing. The foregoing observations will be obtained with TIMETAG and all PSA observations will utilize FLASH=YES. Additionally, obtain at least
one set of identical exposures in both TIME-TAG and ACCUM with FLASH=NO to
verify auto-wavecal capability with each mode and verify Doppler correction with
ACCUM.
IMPLEMENTATION METHOD: Stored commanding
DEPENDENCIES: Execute after verification based on COS15 (Internal NUV
Wavelength Verification)
DURATION: 9 orbits (external); CVZ preferred – not required.
DATA REQUIREMENTS: ~220 Mbytes (22 exposures).
ANALYSES & EXPECTED RESULTS: Science exposure data will be produced.
Evaluate spectral resolution in all cases by assessing profiles of the narrow absorption
lines in the high S/N spectra and compare with specification. Analyze all spectra for
line FWHM as a function of wavelength.
COMMENTS: Proposal TBD
AUTHOR/telephone/email: T. Keyes / 410-338-4975 / keyes@stsci.edu
DATE: 9/27/2007
ACTIVITY TITLE: COS NUV External Spectroscopic Performance - Part 2
ID: COS17
APPLICABLE SMOV REQUIREMENTS: L.10.4.2.3.7.2, L.10.4.2.3.7.3,
L.10.4.2.3.13
DESCRIPTION:
Verify the quality of spectroscopic performance of COS/NUV in terms of spatial
resolution and spectrum resolution. All four NUV gratings should be tested, each at one
central wavelength. For each grating, an external point source will first be acquired and
centered in the PSA, and a spectrum obtained. Additional spectra will be obtained at
positions on both sides of the aperture center in the cross-dispersion direction. These
additional pointings will be 0.25 arcsec apart and there are 7 of them on each side of
center so that we test the light coming from an object even when it is beyond the edge of
the aperture. This leads to 15 pointings per grating. The same test should be done for the
BOA, but only at the on-center position.
HOW THE ACTIVITY IS BEST IMPLEMENTED: Stored commanding
DEPENDENCIES: Execute after verification based on COS15 (Internal NUV
Wavelength Verification)
DURATION: 8 orbits.
DATA REQUIREMENTS:
The total data quantity is modest. TIME-TAG mode should be used. There are 16
spectra per grating (15 for the PSA and 1 for the BOA) for 4 gratings, or 64 total. Each
spectrum is 1024x1024 pixels or 2 Mbytes to the SSR per spectrum. Program total is 128
Mbytes probably executed in two approximately equally-sized visits.
ANALYSES & EXPECTED RESULTS:
This test is to confirm that ground test data provide an accurate indication of the spatial
and spectrum resolution achievable by COS. The choice of source is crucial for the
success of the test. Another SMOV activity (COS16; Part 1 of this test) observes a
continuum source with sharp absorption lines, primarily to test spectrum resolution for
each grating. The current test (Part 2) is primarily for determining the spatial resolution
in COS spectra. To do this, the source should have little or no continuum but should
have narrow (preferably unresolved) emission lines. A small planetary nebula might
serve, but PN generally have significant expansion velocities that lead to oval-shaped
lines that can confuse the analysis. For the NUV, some stars have very bright emission
lines of Mg II at 2800 Å that could be used for this test.
COMMENTS:
AUTHOR/telephone/email:
D. Soderblom/STScI/410-338-4543/drs
2007-10-04
ACTIVITY TITLE: COS NUV Flat Fields
ID: COS18
APPLICABLE SMOV REQUIREMENTS: L.10.4.2.3.7.4
DESCRIPTION: Acquire long NUV flat field exposures using the internal deuterium
calibration lamp with the G185M grating. Use central wavelengths of 1835 Å, 1850 Å,
and 1864 Å. Based on data taken during thermal vacuum testing in 2003 (Test 1750), a
total of 65,000 seconds of data should be sufficient to obtain ~7.5×107 total counts in the
science region of the detector (> 200 counts per pixel, or 1800 counts per 3 x 3 pixel
resolution element).
Take the data as 1800 second exposures, with 12 exposures at each of the 3
central wavelengths.
IMPLEMENTATION METHOD: Stored commanding.
DEPENDENCIES: To be run after NUV Optics Alignment and Focus (COS09)
DURATION: 36 internal orbits
DATA REQUIREMENTS: 36 science exposures each producing approximately 8
Mbytes of data. Total of ~300 Mbytes for the entire program.
ANALYSES & EXPECTED RESULTS: This activity will create a large number of
science exposures which must be combined on the ground in order to create a deep flat
field image with a signal-to-noise ratio high enough to allow flat fielding of science
exposures to a level of 30:1 per resolution element.
COMMENTS:
AUTHOR/telephone/email: David Sahnow/410-516-8503/sahnow@pha.jhu.edu
DATE: 9/28/07
ACTIVITY TITLE: COS NUV Spectroscopic Sensitivity
ID: COS19
APPLICABLE SMOV REQUIREMENTS: L.10.4.2.3.7.5; L.10.4.2.2.1
DESCRIPTION: This activity confirms COS sensitivity versus wavelength over the
entire observable spectrum for all NUV gratings and central wavelength settings.
Perform a precise-centering acquisition and observe an appropriate HST flux standard
star (chosen from the HST prime standard and FASTEX lists) with the PSA. (A limited
BOA characterization is obtained in COS16.) No off aperture-center observations are
performed in this activity (see COS17 for off-center characterizations). Spectra will be
obtained to meet a Poisson S/N criterion of 30 per pixel; higher S/N characterization will
be utilized in routine Cycle 17 calibration.
IMPLEMENTATION METHOD: Stored commanding.
DEPENDENCIES: Execute after confirmations based on analysis of COS15.
DURATION: 15 orbits (external).
DATA REQUIREMENTS: Exposures will produce ~12-15 Mbytes per orbit if
executed in ACCUM mode. There will probably be 3 visits required to complete the
program. Total of 225 Mbytes for the program if executed in ACCUM mode. TIMETAG exposures could produce ~5x as much data.
ANALYSES & EXPECTED RESULTS: Science exposure data will be produced.
Compare observed counts to absolute flux distributions (either model-based for prime
HST standards or observation-based for FASTEX standards) and derive sensitivity
functions for use in calcos.
COMMENTS: Proposal TBD
AUTHOR/telephone/email: T. Keyes / 410-338-4975 / keyes@stsci.edu
DATE: 9/27/2007
ACTIVITY TITLE: COS NUV Structural and Thermal Stability
ID: COS 20
APPLICABLE SMOV REQUIREMENTS: L.10.4.2.3.7.6
DESCRIPTION: Observe a non-variable (preferably, though not required, CVZ)
external target in TIME-TAG mode for three continuous orbits with a single grating,
central wavelength, FP-POS position to examine whether there are signatures of thermal
or structural distortions, to assess photometric stability, and to assess OSM1 drift and
TAGFLASH utility. Additionally observe the same target with repeated TA1 images
over a similar three-orbit period.
IMPLEMENTATION METHOD: Stored commanding
DEPENDENCIES: Execute after verification based on COS15 (Internal NUV
Wavelength Verification)
DURATION: 6 orbits (external); CVZ preferred – not required.
DATA REQUIREMENTS: Approximately 25 Mbytes per orbit or 150 Mbytes for the
program.
ANALYSES & EXPECTED RESULTS: Science exposure data will be produced.
The imaging observation will directly assess any OTA-COS pointing jitter or drifts over
timescales of seconds to hours. Derive an image centroid for every few second interval of
TIME-TAG imaging data (using bins appropriate to establishing ~0.1 pixel accuracy) –
derive rms, excursions, etc of for the centroid position. An assessment of spectral image
drift will be made by analyzing location of features in spectrum of the external target and
by measuring the locations of internal wavecal lamp flashes. Derive the direction and
magnitude of any shifts in position; compare with stability specs. Make comparison with
spacecraft jitter files.
COMMENTS: Proposal TBD
AUTHOR/telephone/email: T. Keyes / 410-338-4975 / keyes@stsci.edu
DATE: 9/27/2007
ACTIVITY TITLE: COS NUV High S/N Verification
ID: COS21
APPLICABLE SMOV REQUIREMENTS: L.10.4.2.3.7.7
DESCRIPTION: Collect data for each NUV grating (TIME-TAG, using multiple FPPOS positions) in order to verify that spectra with a signal-to-noise ratio greater than 30
can be obtained with normal data acquisition and reduction techniques. At least two of
the primary STIS standards and one of the COS FASTEX targets are expected to produce
count rates of more than 0.15 counts/sec/resolution element (and in some cases, much
more) for all of the NUV gratings, with the exact count rate depending on the grating,
central wavelength, stripe, and target. With these count rates, three orbit exposures should
collect enough counts to produce 30:1 S/N calibrated spectra.
IMPLEMENTATION METHOD: Stored commanding.
DEPENDENCIES: To be run after verification based on COS15 (Internal NUV
Wavelength Verification)
DURATION: 12 orbits (verification performed on all gratings)
DATA REQUIREMENTS: 12 science exposures at 4 Mbytes per orbit, if TIME-TAG
is used. Program total ~50 Mbytes.
ANALYSES & EXPECTED RESULTS: Standard data processing techniques will be
used to apply a high-quality flat field (Activity COS18) and combine the exposures into
spectra with a signal-to-noise ratio of better than 30 per resolution element.
COMMENTS:
AUTHOR/telephone/email: David Sahnow/410-516-8503/sahnow@pha.jhu.edu
DATE: 10/4/07
ACTIVITY TITLE: COS FUV Detector Door Open
ID: COS22
APPLICABLE SMOV REQUIREMENTS: L.10.4.2.2.2, L.10.4.2.2.3
DESCRIPTION: Open the FUV detector door so that the detector can begin to outgas
and light can reach the microchannel plates.
IMPLEMENTATION METHOD: Real-time commanding
DEPENDENCIES: To be run only after the pressure in the instrument cavity has been
below 100 micro-Torr for at least 12 consecutive hours. This activity must be completed
before any other FUV detector high voltage activities occur. Also, COS02 (COS
Onboard Memory Check) and COS03 (COS Science Data Buffer Check) must have
executed successfully prior to this activity.
DURATION: 1 orbit (internal)
DATA REQUIREMENTS: Housekeeping data only.
ANALYSES & EXPECTED RESULTS: No required analysis.
COMMENTS:
AUTHOR/telephone/email: David Sahnow/410-516-8503/sahnow@pha.jhu.edu
DATE: 9/28/07
ACTIVITY TITLE: COS FUV Detector Initial High Voltage Turn On and Ramp Up
ID: COS23
APPLICABLE SMOV REQUIREMENTS: L.10.4.2.1.7, L.10.4.2.2.2; L.10.4.2.1.2
DESCRIPTION: The high voltage on the COS FUV XDL detector will be turned on for
the first time and ramped to its nominal voltage. The ramp up will be done slowly, and in
multiple steps. The basic procedure is as follows:
1) Turn the FUV HV on, but do not ramp to the HVLow setting.
2) Copy and dump the DCE RAM.
3) Set NSSC-1 COS event flag 3 and wait at least 4 hours.
4) If analysis of data indicates that all is well, flag 3 will be cleared via real-time
command.
5) Ramp the FUV HV to the HVLow setting.
6) Copy and dump the DCE RAM.
7) Set NSSC-1 COS event flag 3 and wait at least 4 hours.
8) If analysis of data indicates that all is well, flag 3 will be cleared via real-time
command.
The following steps are repeated 4 times, differing only in the HV setting. The segment
A/B HV count settings for these 4 iterations will be 154/151, 160/157, 166/163, and
172/169.
9) Ramp at 10 sec/step to a HV setting above HVLow.
10) Copy and dump the DCE RAM.
11) Take a time-tag DARK exposure (5 minutes).
12) Take a time-tag PtNe#1 lamp exposure (250 sec).
13) Wait at least 4 hours.
14) Copy and dump the DCE RAM.
15) Transition back to HVLow.
16) Set NSSC-1 COS event flag 3 and wait long enough for data to be analyzed and the
flag to be cleared (~1 day).
17) Ramp at 10 sec/step to HVNom settings (178/175).
18) Copy and dump the DCE RAM.
19) Take a time-tag DARK exposure (5 minutes).
20) Take a time-tag PtNe#1 lamp exposure (250 sec).
21) Wait at least 8 hours.
22) Copy and dump the DCE RAM.
23) Take a time-tag DARK exposure (5 minutes).
24) Take a time-tag PtNe#1 lamp exposure (250 sec).
25) Transition back to HVLow.
IMPLEMENTATION METHOD: Stored and real-time commanding
DEPENDENCIES: To be run only after the FUV detector door has been opened
(activity COS22) and the internal pressure is less than 10 micro-Torr for 12 consecutive
hours (CARD item).
DURATION: 6 internal orbits – one per day for 6 days
DATA REQUIREMENTS: 12 time-tag dark exposures. Total is < 1Mbyte.
ANALYSES & EXPECTED RESULTS: This activity will verify the normal
operation of the FUV detector. Dark exposures, DCE dump data, and engineering
telemetry must be examined after each step of the ramp-up in order to verify the proper
operation of the detector before continuing. Exposures and telemetry must be examined
again after the full ramp up before subsequent HV operations occur.
COMMENTS: This proposal requires Special Commanding to execute.
AUTHOR/telephone/email: David Sahnow/410-516-8503/sahnow@pha.jhu.edu (Alan
Welty / Jason McPhate)
DATE: 9/28/07
ACTIVITY TITLE: COS FUV Detector Dark Count Measurement
ID: COS24
APPLICABLE SMOV REQUIREMENTS: L.10.4.2.1.8; L.10.4.2.3.8
DESCRIPTION: Measure the FUV detector dark rate by taking long science exposures
with no light on the detector.
IMPLEMENTATION METHOD: Stored commanding
DEPENDENCIES: To be run no less than 2 days after the FUV Detector Initial Turn
On (COS23). COS internal pressure gauge must be off for this and subsequent activities.
DURATION: 10 orbits (6500 seconds per exposure) (internal)
DATA REQUIREMENTS: 10 dark time-tag exposures. Total < 2Mbytes.
ANALYSES & EXPECTED RESULTS: Verifies TIME-TAG mode for FUV. The
detector dark rate and spatial distribution of counts will be compared to pre-launch data
in order to verify the nominal operation of the detector, and for use in the calibration
pipeline. Variations of count rate as a function of orbital position may be analyzed to find
dependence of dark rate on proximity to the SAA.
COMMENTS:
AUTHOR/telephone/email: David Sahnow/410-516-8503/sahnow@pha.jhu.edu
DATE: 10/4/07
ACTIVITY TITLE: COS FUV Detector Internal Functionality and Operation
ID: COS25
APPLICABLE SMOV REQUIREMENTS: L.10.4.2.1.8; L.10.4.2.3.8
DESCRIPTION: Verify the functionality and operation of the FUV detector using
internal sources. Obtain several science exposures in TIME-TAG using both the
DEUTERIUM and Pt/Ne lamps. Multiple 60 second exposures of the PtNe lamp should
be taken after an OSM move in order to obtain a coarse characterization of the OSM
drift. A single DEUTERIUM exposure of 60 seconds should also be taken.
IMPLEMENTATION METHOD: Stored commanding.
DEPENDENCIES: To be run no less than 2 days after the FUV Detector Initial Turn
On (COS23). COS internal pressure gauge must be off for this and subsequent activities.
DURATION: 1 internal orbit.
DATA REQUIREMENTS: < 1 MByte
ANALYSES & EXPECTED RESULTS: The science images will be compared with
similar images taken on the ground before launch. The locations of the spectra will be
used to determine the initial locations of the spectra in the cross-dispersion direction so
that modifications can be made to patchable constants used for peak ups. The OSM drift
will be compared to thermal vac data to determine if its characteristics have changed.
COMMENTS:
AUTHOR/telephone/email: David Sahnow/410-516-8503/sahnow@pha.jhu.edu
DATE: 10/4/07
ACTIVITY TITLE: COS FUV Optical Alignment
ID: COS 26
APPLICABLE SMOV REQUIREMENTS: L.10.4.2.1.8; L.10.4.2.3.9; L10.4.2.3.10
DESCRIPTION: After FUV detector functionality has been confirmed in COS25 and
the initial focus updates determined in COS08, a sequence of 11-15 FUV exposures of a
sharp-lined external target will be made with each grating (4 orbits per grating) to
perform a fine-focus sweep. After the data are analyzed, a patchable constant SMS
update of OSM1 focus for each grating will be uplinked. Observations require high S/N
and should be taken in TIME-TAG (FLASH=YES) mode.
IMPLEMENTATION METHOD: Stored commanding
DEPENDENCIES: COS 25 (FUV Detector Functionality and Operation) and COS 08
(COS to FGS Alignment)
DURATION: 12 orbits (external)
DATA REQUIREMENTS: ~900 Mbytes (45 exposures).
ANALYSES & EXPECTED RESULTS: Science exposure data will be produced,
downlinked, and analyzed. The data will be analyzed by IDL software. The data should
be available for analysis within 24 hours of the observations to facilitate rapid updates of
the nominal focus.
COMMENTS: Proposal TBD
AUTHOR/telephone/email: T. Keyes (G. Hartig) / 410-338-4975 / keyes@stsci.edu
DATE: 9/26/2007
ACTIVITY TITLE: COS Internal FUV Wavelength Measurement
ID: COS27
APPLICABLE SMOV REQUIREMENTS: L.10.4.2.3.8
DESCRIPTION: After completion of FUV optical alignment and focus (COS26), an
initial series of internal wavelength calibration exposures will be obtained with each
grating and central wavelength combination at the default FP-POS. One central
wavelength position with each grating will be observed at all FP-POS.
In a separate visit that is not in the critical path to establishing the operational science
wavelength scale, wavelength calibration spectra with the alternate PtNe lamp (lamp 2)
will be obtained with each grating at one central wavelength and FP-POS position. The
lamp 2 visit can conveniently be executed during the period between visit 1 of the present
activity (COS27) and COS30 while SIAF and OSM position updates are being
implemented. The entire activity will be conducted as a series of internal exposures
IMPLEMENTATION METHOD: Stored commanding
DEPENDENCIES: COS 26 (COS FUV Optics Alignment and Focus) required prior to
execution of visit 1. Visit 2 should execute after visit 1 and, if possible, prior to COS30.
DURATION: 3 orbits (internal)
DATA REQUIREMENTS: Estimate science bits to SSR. Approximately 4 Mbytes for
visit 1 and 2 Mbytes for visit 2. Total < 6 Mbytes.
ANALYSES & EXPECTED RESULTS: Science exposure data will be produced.
Dispersion relations will be obtained for each spectral element, central wavelength, and
FP-POS for lamp 1 (default lamp). Lamp performance characteristics will be established
for the alternate lamp (lamp 2).
COMMENTS: Proposal TBD
AUTHOR/telephone/email: T. Keyes / 410-338-4975 / keyes@stsci.edu
DATE: 10/3/2007
ACTIVITY TITLE: COS FUV Target Acquisition Algorithm Verification
ID: COS28
APPLICABLE SMOV REQUIREMENTS: L.10.4.2.3.11.1; L.10.4.2.1.8
DESCRIPTION:
Verify the ability of the COS FSW to place an isolated point source at the center of the
aperture, both for the BOA and PSA, using dispersed light from the object using an FUV
grating. The various options for target centering should be exercised and shown to work
properly. This test is for acquisitions in dispersed-light mode only.
HOW THE ACTIVITY IS BEST IMPLEMENTED: Stored commanding
DEPENDENCIES:
This activity should follow COS26, “FUV Optics Alignment and Focus,” and COS12,
“COS NUV Dispersed-light Acquisition Algorithm Verification.”
DURATION: 6 orbits (external)
DATA REQUIREMENTS:
Only very small quantities (< 1Mbyte) of data are produced for downlinking because
only header information is provided.
ANALYSES & EXPECTED RESULTS:
Successful centering of a point source within both the PSA and BOA is verified, using all
the centering options available. This activity verifies that the centering error does not
exceed a given threshold, viz. 0.1 arcsec. Verifies routine FUV detector subarray
readout.
COMMENTS:
This test should be done with several combinations of FUV grating and central
wavelength. For instance, grating G140L produces a stripe on only one detector segment,
whereas G130M and G160M both produce stripes on both segments. Different central
wavelengths are vulnerable to different airglow emission lines, for which different subarrays have been written into the FSW. Because of the significance of the airglow lines
for affecting dispersed-light target acquisitions, this activity should be done in the
daylight portions of orbits whenever possible so that the worst case is tested.
The following grating/wavelength combinations should suffice to confirm that the
acquisition algorithms work: G140L/1105; G140L/1230; G130M/1291; G130M/1309;
G130M/1327; G160M/1577; G160M/1600; G160M/1623. Thus there are eight
instrument configurations to check. Only a subset of these need be done with the BOA:
G140L/1105; G140L/1230; G130M/1309; G160M/1600. It is assumed that the more
complete test with the PSA verifies that the detector sub-arrays have been chosen
properly and that the algorithms work. The BOA test has been minimized to test only
that the acquisition procedure also properly centers an object when the BOA is used.
The dispersed-light acquisition procedure does not return an image of the aperture by
which to judge the quality of the centering. Therefore this test will include short
exposures of spectra after each acquisition to verify the procedures.
This activity comprises two separate visits. Visit 1 will include:
•
Acquisition of an isolated point source with the PSA. This portion should start
with an ACQ/SEARCH and SCAN-SIZE=3 to ensure a successful acquisition
even if the initial alignment is imperfect. The default STEP-SIZE of 1.767 arcsec
should be used. All three CENTER options (FLUX-WT, FLUX-WT-FLR, and
BRIGHTEST) should be exercised, with a short spectrum obtained after each
centering, followed by a small displacement.
•
Use of ACQ/PEAKXD to peak-up the spectrum in the cross-dispersion direction.
The grating and wavelength are the same as for ACQ/SEARCH, and default
parameters are used. A spectrum is then obtained in TIME-TAG mode.
•
Use of ACQ/PEAKD to center the spectrum in the along-dispersion direction,
again with default parameters. Again, a spectrum is obtained, in TIME-TAG
mode.
Once this has been done for the first grating/wavelength, the object should be displaced
in the aperture and then the series should be repeated for each additional
grating/wavelength, except that the initial ACQ/SEARCH can be omitted.
Visit 1 is likely to use 4 orbits.
Visit 2 repeats everything in Visit 1 except the BOA is used on a brighter star. Visit 2
will be constrained to use 2 orbits by limiting the set of grating/wavelength combinations
used.
The target or targets can likely be chosen from the astrometric field in M35. Use of the
ETC can enable an optimum target to be chosen based on spectral type (from optical
colors).
AUTHOR/telephone/email:
D. Soderblom/STScI/410-338-4543/drs
2007-10-04
ACTIVITY TITLE: COS FUV Internal/External Wavelength Scales
ID: COS29
APPLICABLE SMOV REQUIREMENTS: L.10.4.2.3.12.1; L.10.4.2.1.8; L.10.4.2.1.2
DESCRIPTION: Observe an external radial velocity standard target (preferably, though
not required, in CVZ) in TIME-TAG (FLASH=YES) mode with all grating and central
wavelength combinations. The purpose is to obtain zero-point offsets for the wavelength
scale (internal wavecal lamp scale to external standard wavelength scale) for all central
wavelengths. Following this determination, adjustments of the nominal science target
spectral range for each grating and central wavelength combination will be made via
SMS patchable constant for nominal OSM1 positions corresponding to each central
wavelength. Subsequent to this modification of the wavelength scale (and its verification
via analysis of COS30), science-related operations and EROs can commence.
IMPLEMENTATION METHOD: Stored commanding
DEPENDENCIES: Execute after first epoch of COS27 (Internal FUV Wavelength
Measurement); following analysis, update OSM position settings for each central
wavelength via SMS patchable constant; COS30 is executed after these updates.
DURATION: 4 orbits (external); CVZ preferred – not required.
DATA REQUIREMENTS: ~240 Mbytes (12 exposures).
ANALYSES & EXPECTED RESULTS: Science exposure data will be produced.
Determination of wavelength scale offsets between the internal wavecal lamps and the
external well-centered science target will be made for each grating and central
wavelength combination. The actual observed full spectral range will be determined and
compared with desired spectral range. An update of the commanding correspondence of
OSM1 hardware position and central wavelengths will be made and uplinked via SMS
patchable constant. After this change COS30 will be executed to confirm results. This
activity also verifies TAGFLASH mode (FLASH=YES). Program also verifies some
aspects of single-segment operation. Program also verifies operation with segment A
only. Some longer exposures will also be used to evaluate OSM drifts.
COMMENTS: Proposal TBD
AUTHOR/telephone/email: T. Keyes / 410-338-4975 / keyes@stsci.edu
DATE: 9/27/2007
ACTIVITY TITLE: COS Internal FUV Wavelength Verification
ID: COS30
APPLICABLE SMOV REQUIREMENTS: L.10.4.2.3.12.1; L.10.4.2.1.2
DESCRIPTION: Subsequent to the uplink of the OSM1 position updates derived from
the determination of the wavelength-scale zero points and desired spectral ranges for each
grating in activity COS29, an internal wavelength calibration spectrum using the default
PtNe lamp (lamp 1) with each FUV grating at each central wavelength setting and each
FP-POS position will be obtained for verification purposes. The entire activity will be
conducted as a series of internal exposures. This verification is required prior to the
enabling of COS ERO and science operations. Exposures following grating changes will
require several repetitions to avoid mechanism drifts.
IMPLEMENTATION METHOD: Stored commanding
DEPENDENCIES: Execute after zero-points and wavelength ranges are established for
external sources and updated following COS29
DURATION: 4 orbits (internal)
DATA REQUIREMENTS: The entire program will produce about 50 Mbytes of data,
however the program will likely be executed in 4 separate equally sized visits each
producing 10-12 Mbytes of data to the SSR.
ANALYSES & EXPECTED RESULTS: Science exposure data will be produced.
Dispersion relations will be obtained for each spectral element, central wavelength, and
FP-POS for lamp 1 (default lamp). The repeated exposures will be evaluated to assess
mechanism drifts. Program also verifies operation with segment A only.
COMMENTS: Proposal TBD
AUTHOR/telephone/email: T. Keyes / 410-338-4975 / keyes@stsci.edu
DATE: 10/3/2007
ACTIVITY TITLE: COS FUV External Spectroscopic Performance – Part 1
ID: COS 31
APPLICABLE SMOV REQUIREMENTS: L.10.4.2.3.12.2; L.10.4.2.3.13;
L.10.4.2.1.8
DESCRIPTION: This activity measures absorption line spectral resolution at one
central wavelength with each FUV grating for both PSA and BOA apertures and
evaluates spectral resolution at offset pointings characteristic of routine COS observation.
Perform precision-centering target acquisition for an external target with sharp, welldefined absorption lines. Obtain moderately high S/N (~50 or greater per resel counting
statistics if possible) observations at one central wavelength setting for each FUV grating
with BOA and with PSA. Using the PSA repeat the sequence of observations at each of
four additional POS-TARG pointings to form a diamond whose vertices are displaced
0.25 arcsec in either X or Y from the initial pointing. The foregoing observations will be
obtained with TIME-TAG and all PSA observations will utilize FLASH=YES.
Additionally, obtain at least one set of identical exposures in both TIME-TAG and
ACCUM with FLASH=NO to verify auto-wavecal capability with each mode and verify
Doppler correction with ACCUM.
IMPLEMENTATION METHOD: Stored commanding
DEPENDENCIES: Execute after verification based upon analysis of COS 30 (Internal
FUV Wavelength Verification).
DURATION: 8 orbits (external); CVZ preferred – not required.
DATA REQUIREMENTS: ~570 Mbytes. (11 TIME-TAG exposures and 1 ACCUM
exposure).
ANALYSES & EXPECTED RESULTS: Science exposure data will be produced.
Evaluate spectral resolution in all cases by assessing profiles of the narrow absorption
lines in the high S/N spectra and compare with specification. Analyze all spectra for
line FWHM as a function of wavelength. Verifies ACCUM mode for FUV.
COMMENTS: Proposal TBD
AUTHOR/telephone/email: T. Keyes / 410-338-4975 / keyes@stsci.edu
DATE: 9/27/2007
ACTIVITY TITLE: COS FUV External Spectroscopic Performance - Part 2
ID: COS32
APPLICABLE SMOV REQUIREMENTS: L.10.4.2.3.12.2, L.10.4.2.3.12.3,
L.10.4.2.3.13
DESCRIPTION:
Verify the quality of spectroscopic performance of COS/FUV in terms of spatial
resolution and spectrum resolution. All three FUV gratings should be tested, each at one
central wavelength. For each grating, an external point source will first be acquired and
centered in the PSA, and a spectrum obtained. Additional spectra will be obtained at
positions on both sides of the aperture center in the cross-dispersion direction. These
additional pointings will be 0.25 arcsec apart and there are 7 of them on each side of
center so that we test the light coming from an object even when it is beyond the edge of
the aperture. This leads to 15 pointings per grating. The same test should be done for the
BOA, but only at the on-center position.
HOW THE ACTIVITY IS BEST IMPLEMENTED: Stored commanding
DEPENDENCIES: This activity should follow verification based on COS30 (Internal
FUV Wavelength Verification)
DURATION: 6 orbits.
DATA REQUIREMENTS:
The total data quantity is modest. TIME-TAG mode should be used. There are 16
spectra per grating (15 for the PSA and 1 for the BOA) for 3 gratings, or 48 total. Each
spectrum is 16384x256x2 bytes (or 8 Mbytes). Program total is ~400 Mbytes.
ANALYSES & EXPECTED RESULTS:
This test is to confirm that ground test data provide an accurate indication of the spatial
and spectrum resolution achievable by COS. The choice of source is crucial for the
success of the test. Another SMOV activity (COS31; Part 1 of this test) observes a
continuum source with sharp absorption lines, primarily to test spectrum resolution for
each grating. The current test (Part 2) is primarily for determining the spatial resolution
in COS spectra. To do this, the source should have little or no continuum but should
have narrow (preferably unresolved) emission lines. A small planetary nebula might
serve, but PN generally have significant expansion velocities which lead to oval-shaped
lines that can confuse the analysis. A young, late-type main sequence star may serve as
the source. Such stars have a number of chromospheric and transition region emission
lines to observe. Emission from such objects is at the rest velocity of the object. If a
suitable object of suitable brightness is found, then the necessary data should be realized
in six orbits, but an accurate orbit estimate will not be possible until Phase II.
COMMENTS:
AUTHOR/telephone/email:
D. Soderblom/STScI/410-338-4543/drs
2007-10-04
ACTIVITY TITLE: COS FUV External Flat Fields
ID: COS33
APPLICABLE SMOV REQUIREMENTS: L.10.4.2.3.12.4
DESCRIPTION: Obtain external spectra at ~6 different positions along the crossdispersion direction (and at multiple FP-POS positions) on the FUV detector in order to
obtain a flat field. Choose the positions of the target in the aperture and the gratings to
maximize the coverage on the detector in the cross-dispersion direction and cover the
entire region where science spectra will fall. Count rates of up to ~50,000 counts/second
can be expected, depending on the final choice of targets. With these count rates, one
exposure at each cross-dispersion position should be sufficient to obtain a high enough
signal-to-noise ratio. If the count rates allow it, these exposures should be done in TIMETAG mode.
IMPLEMENTATION METHOD: Stored commanding.
DEPENDENCIES: To be run after verification based on COS30 (Internal FUV
Wavelength Verification)
DURATION: 6 external orbits.
DATA REQUIREMENTS: Up to ~600 Mbytes total, depending on the target chosen
and whether the exposures are taken in TIME-TAG mode.
ANALYSES & EXPECTED RESULTS: The data taken during this activity will be
combined to create a two-dimensional FUV flat field for use in the calcos pipeline.
COMMENTS:
AUTHOR/telephone/email: David Sahnow/410-516-8503/sahnow@pha.jhu.edu
DATE: 10/4/07
ACTIVITY TITLE: COS FUV Spectroscopic Sensitivity
ID: COS34
APPLICABLE SMOV REQUIREMENTS: L.10.4.2.3.12.5; L.10.4.2.2.1; L.10.4.2.1.2
DESCRIPTION: This activity confirms COS sensitivity versus wavelength over the
entire observable spectrum for all FUV gratings and central wavelength settings.
Perform a precise-centering acquisition and observe an appropriate HST flux standard
star (chosen from the HST prime standard and FASTEX lists) with the PSA. (A limited
BOA characterization is obtained in COS31.) No off aperture-center observations are
performed in this activity (see COS32 for off-center characterizations). Spectra will be
obtained to meet a Poisson S/N criterion of ~30 per resel or higher; substantially higher
S/N characterization will be utilized in routine Cycle 17 calibration.
IMPLEMENTATION METHOD: Stored commanding
DEPENDENCIES: Execute after confirmations based on analysis of COS30.
DURATION: 12 orbits (external).
DATA REQUIREMENTS: ~1000 Mbytes. (48 exposures).
ANALYSES & EXPECTED RESULTS: Science exposure data will be produced.
Compare observed counts to absolute flux distributions (either model-based for prime
HST standards or observation-based for FASTEX standards) and derive sensitivity
functions for use in calcos. Program also verifies operation with segment B only.
COMMENTS: Proposal TBD
AUTHOR/telephone/email: T. Keyes / 410-338-4975 / keyes@stsci.edu
DATE: 9/27/2007
ACTIVITY TITLE: COS FUV Structural and Thermal Stability
ID: COS35
APPLICABLE SMOV REQUIREMENTS: L.10.4.2.3.12.6
DESCRIPTION: Observe a non-variable (preferably, though not required, CVZ)
external target in TIME-TAG mode for three continuous orbits with a single grating,
central wavelength, FP-POS position to examine whether there are signatures of thermal
or structural distortions, to assess photometric stability, and to assess OSM1 drift and
TAGFLASH utility.
IMPLEMENTATION METHOD: Stored commanding
DEPENDENCIES: Execute after verification based on COS30 (Internal FUV
Wavelength Verification)
DURATION: 3 orbits (external); CVZ preferred – not required.
DATA REQUIREMENTS: ~150 Mbytes (3 exposures).
ANALYSES & EXPECTED RESULTS: Science exposure data will be produced.
An assessment of image drift will be made by analyzing location of features in spectrum
of the external target and by measuring the locations of internal wavecal lamp flashes.
Derive the direction and magnitude of any shifts in position; compare with stability specs.
Make comparison with spacecraft jitter files.
COMMENTS: Proposal TBD
AUTHOR/telephone/email: T. Keyes / 410-338-4975 / keyes@stsci.edu
DATE: 9/27/2007
ACTIVITY TITLE: COS FUV High S/N Verification
ID: COS36
APPLICABLE SMOV REQUIREMENTS: L.10.4.2.3.12.7
DESCRIPTION: Collect data for a single central wavelength on each FUV grating in
order to verify that spectra with a signal-to-noise ratio greater than 30 can be obtained
with normal data acquisition and reduction techniques. Standard continuum targets are
available with count rates on the order of ~0.5 to 1.0 counts/sec/resolution element in the
FUV channels without exceeding the global count rate threshold. These targets are
expected to give enough counts in 1 – 2 orbits for 30:1 calibrated spectra. Obtain 2 orbits
of data for a single central wavelength for each grating. Use multiple FP-POS positions.
These observations should be made in TIME-TAG mode if the count rate of the target is
in the appropriate range.
IMPLEMENTATION METHOD: Stored commanding.
DEPENDENCIES: To be run after verification based on Internal FUV Wavelength
Verification (COS30)
DURATION: 6 orbits.
DATA REQUIREMENTS: Up to 600 Mbytes total, depending on target and observing
mode.
ANALYSES & EXPECTED RESULTS: Standard data processing techniques will be
used to apply a high-quality flat field (Activity COS33) and combine the exposures into
one-dimensional spectra with a signal-to-noise ratio of better than 30 per resolution
element.
COMMENTS:
AUTHOR/telephone/email: David Sahnow/410-516-8503/sahnow@pha.jhu.edu
DATE: 10/4/07