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