From: Space Telescope Science Institute
Posted: Thursday, January 31, 2008
HUBBLE SPACE TELESCOPE DAILY REPORT # 4537
Continuing to collect World Class Science
PERIOD COVERED: UT January 30, 2008 (DOY 030)
HST/FGS 1-Gyro On-Orbit Checkout
This proposal uses an FGS as an astrometer to observe bright stars (V<12) in Position mode, with the two other FGSs operating as guiders. The data obtained by the astrometer will be used to "witness" the pointing performance of the Observatory in FineLock under 1-gyro operations. Each visit of this proposal will have a single Pos mode exposure, the duration of which is to be set by target visibility or by other tests being conducted in parallel or in sequence with this proposal. For planning purposes this proposal specifies an exposure time of 40 minutes, but this can be adjusted as needed.
HST/PCS 1-Gyro On-orbit Checkout
This proposal contains the part of the on-orbit test that cannot be satisfied by the science proposals. This includes testing certain M1G, T1G and F1G capabilities that could potentially compromise any science data collection, but are needed to validate the robustness of 1-gyro science mode.
HST/WFPC2 1-gyro On-orbit Checkout
The goal of this program is to verify the performance of the HST under One Gyro operation.
As in previous Two Gyro Testing and Orbital Verification programs the analysis will be done by characterizating the Point Spread Function (PSF) of PC1 in the F555W filter.
Two Primary issues addressed by this proposal: - PSF structure and repeatability - Pointing, stability, and offset accuracy.
PSF will be characterized as a function of - exposure time - guide star brightness - sky position
For the Pointing we will characterize: - repeatability of small offsets - stability within visibility period - stability across occultations. as a function of the guide star brightness
The Program requires fifteen orbits: (7 for the main target, 1 for the secondary target) for two gyro mode, then for 1-gyro mode. The structure of the visits is identical to the visits executed as part of the program 10458 "ACS and WFPC2 TGSMOV Two-Gyro PSF, Pointing, and Dither Test" with the only exception of the NICMOS parallel that have been removed.
The target selection is based on the visibility in the mid January to mid February 2008 timeframe. Final target selection will be confirmed after the analysis of the guide star availability.
Observations of Mars and 2007 WD5
We are proposing to observe 2007 WD5 prior to its possible impact with Mars. In the event that an impact does occur, we will also observe the asteroid as it approaches Mars, the impact itself, and the aftermath of the impact. HST has unique capabilities to observe this potentially very unusual event.
FLIGHT OPERATIONS SUMMARY:
Significant Spacecraft Anomalies: (The following are preliminary reports of potential non-nominal performance that will be investigated.)
HSTARS: None =20 COMPLETED OPS REQUEST: 18189-0 - Gyro residual value in TMDIAG=20 18183-3 - T1G Commanding for OGS OOT=20 18182-6 - OGS On-Orbit Test
COMPLETED OPS NOTES: (None)
SCHEDULED SUCCESSFUL FGS GSacq 06 06 FGS REacq 01 01 OBAD with Maneuver 26 26
Flash Report - Day 2 One Gyro Science (OGS)/Kalman Filter Sun Point (KFSP) OOT
Since the start of the OGS SMS (029/10:00) there have been 12 acquisitions and 42 OBADs. All acquisitions and OBADs have been successful. We first entered F1G mode at 029/17:08 for the first science orbit (astrometry observation). The Mars moving target observation began at 030/10:50. We continued executing Ops Request 18182-6 containing the script for test execution. Performance appeared nominal with analysis on-going.
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