SPACE TELESCOPE SCIENCE INSTITUTE
SMOV3B Project Review: FGS Overview
• A new FGS will not be installed.
• The ability to acquire guide stars will be demonstrated in
SMOV3B.
• The calibration database for the FGSs guide star operations will be
verified.
• The calibration database for FGS astrometry will be verified.
• The pointing performance and jitter characteristics of HST with
new solar arrays and NCS operating at a cold steady state will be
assessed.
25 January 2001
Pre SM3b Project Review: FGS
Ed Nelan - 1
SPACE TELESCOPE SCIENCE INSTITUTE
SMOV3B Project Review: FGS Activities
Activity FGS/OTA-01
Title: Guide Star Acquisition Verification
SMOV Requirement J.10.4.8.5
• Description:
– Acquire guide star pairs in finelock using 2 FGSs. Cycle through all 3 FGSs so
that each in turn acquires the primary guide star.
– Demonstrate re-acquisition capability by (1) acquiring guide stars, (2) track for
~5 minutes, (3) drop to gyros, (4) require guide star pair in finelock.
• Dependencies: J.10.4.8.4, Gyro to FHST alignment.
• Resources: 3 HST orbits (within BEA).
25 January 2001
Pre SM3b Project Review: FGS
Ed Nelan - 2
SPACE TELESCOPE SCIENCE INSTITUTE
SMOV3B Project Review: FGS Activities
Activity FGS/OTA-02
Title: Verification of Operational FGS Calibrations
SMOV Requirement J.10.4.7.2.1
• Description (for Position Mode observations):
– Observe standard stars from the M35 cluster in Position Mode in each FGS.
– Compare their relative angular positions to pre-SM3B baseline data (acquired
as part of the SMOV plan) to test for changes in the optical distortions for a
given FGS.
– Using special guide stars, test for changes to the FGS-FGS alignment by
comparing post-SM3B data to pre-SM3B baseline data.
25 January 2001
Pre SM3b Project Review: FGS
Ed Nelan - 3
SPACE TELESCOPE SCIENCE INSTITUTE
25 January 2001
Pre SM3b Project Review: FGS
Ed Nelan - 4
SPACE TELESCOPE SCIENCE INSTITUTE
SMOV3B Project Review: FGS Activities
Activity FGS/OTA-02 (continued)
• Description (for Transfer Mode observations):
– Obtain S-curves at the center of each FGS by observing standard star
Upgren69 with both the F583W filter and the 2/3 Pupil.
– Compare post-SM3B data to pre-SM3B baseline data (acquired as part of
SMOV plan).
– determine the reliability of the FGS acquisition commanding parameters.
• Dependencies: J.10.4.8.5 (verify guide star acquisition).
• Resources: 12 HST orbits, 6 before, 6 after SM3B.
– Reduces the OTA/Astrometry Cycle 10 calibration plan request by 6 orbits
25 January 2001
Pre SM3b Project Review: FGS
Ed Nelan - 5
SPACE TELESCOPE SCIENCE INSTITUTE
SMOV3B Project Review: FGS Activities
Activity FGS/OTA-03
Title: FGS Mini-OFAD Contingency
SMOV Requirement J.10.4.7.2.2
• Description:
– If the results of FGS/OTA-02 indicate that the optical distortions within a
given FGS are such that the operational calibration database is not valid, the
optical distortions will be re-calibrated by a mini-OFAD. Databases will be repopulated with the updates. This is a contingency activity.
• Dependencies: J.10.4.7.2.1
• Resources: 4 HST orbits per (as needed) FGS.
25 January 2001
Pre SM3b Project Review: FGS
Ed Nelan - 6
SPACE TELESCOPE SCIENCE INSTITUTE
SMOV3B Project Review: FGS Activities
Activity FGS/OTA-04
Title: FGS-to-FGS Alignment Contingency
SMOV Requirement J.10.4.7.2.2
• Description:
– If the results of FGS/OTA-02 indicate that the FGS-to-FGS alignments have
changed as a result of SM3B and are out of tolerance, a new FGS-to-FGS
alignment test for the appropriate FGS(s) will be executed. Databases will be
re-populated with the updates. This is a contingency activity.
• Dependencies: J.10.4.7.2.1
• Resources: 4 HST orbits per (as needed) FGS.
25 January 2001
Pre SM3b Project Review: FGS
Ed Nelan - 7
SPACE TELESCOPE SCIENCE INSTITUTE
SMOV3B Project Review: FGS Activities
Activity FGS/OTA-05
Title: FGS K-factor Determination Contingency
SMOV Requirement J.10.4.7.2.2
• Description:
– If the results of FGS/OTA-02 indicate that the S-curves in a given FGS have
changed to such an extent that the commanded guide star acquisition
parameters values are no longer reliable, S-curves will be obtained at the 5
points of light position for the specific FGS to gather the data needed to update
the commanding database. This is a contingency activity.
• Dependencies: J.10.4.7.2.1
• Resources: 4 HST orbits per (as needed) FGS.
25 January 2001
Pre SM3b Project Review: FGS
Ed Nelan - 8
SPACE TELESCOPE SCIENCE INSTITUTE
SMOV3B Project Review: FGS Activities
Activity FGS/OTA-06
Title: FGS Jitter Test
SMOV Requirement J.10.4.7.2.5
• Description:
– FGS1r will be used to determine the pointing performance and jitter
characteristics of HST with the new solar arrays while the NCS is operating
under cold steady state. FGS1r will observe selected stars across its field of
view in both Position and Transfer Mode. The observations will occur within
the BEA. A baseline set will be obtained before NCS turn-on.
• Dependencies: J.10.4.8.5 (verify guide star acquisition)
• Resources: 4 HST orbits
25 January 2001
Pre SM3b Project Review: FGS
Ed Nelan - 9
SPACE TELESCOPE SCIENCE INSTITUTE
SMOV3B Project Review: FGS Activities
Activity FGS/OTA-07
Title: FGS1r Astrometer Calibration Verification
SMOV Requirement J.10.4.7.3.1
• Description:
– The post-SM3B optical field angle distortions, plate scale, and S-curve
amplitude and morphology will be compared to pre-SM3B baseline data. If
changes are within the tolerance of the astrometry error budget, FGS1r will be
certified for astrometry science.
• Dependencies: J.10.4.7.2.1
• Resources: Data will be obtained from FGS/OTA-02
25 January 2001
Pre SM3b Project Review: FGS
Ed Nelan - 10