Page History
...
Table 1: Key Guide Star Catalog releases and associated errors
Catalog | Release Date | Mean Epoch of catalog positions | Typical errors | Worst errors | Total Error (including SI to FGS alignment) | Comment |
|---|---|---|---|---|---|---|
| GSC 2.4.0 + Gaia Fit | Dec 2019 | 2015.5 | 0.01" | 0.01" | WCSNAME='FIT_[REL|IMG]_GAIADR[12]' | |
GSC 2.4.0 | Oct 2017 | 2015.0 | 0.03” | ~0.2” | GSC2.3.4 aligned to Gaia DR1 WCSNAME='IDC*-GSC240', 'IDC*-HSC30' | |
| GSC 2.3.3 | Oct 2009 | WFC3 installed May 2009 | ||||
GSC 2.3.2 | Oct 2005 | 1992.5 | 0.3” | 0.75” | ~0.3” | |
GSC 2.2.0 | Jun 2001 | ACS installed Mar 2002 | ||||
GSC 2.0 | Jan 2000 | Science target fields only; GSC2 summary | ||||
GSC 1.1 | Aug 1992 | 1981.8 | 0.5” | ~1” | ~1” | First version published for the user community Used by HST operations prior to Cycle 15 WFPC2 installed Dec 1993 |
GSC 1.0 | Jun 1989 | 1-2” |
HST Astrometry Project
The coordinates populated in the FITS headers of HST observations retrieved from DADS (the HST Data Archiving and Distribution Service) were derived based on the guide star coordinates in use at the time of the observation. As the accuracy in these catalogs were refined over time, the pointing accuracy of HST has also improved. Table 1 lists the catalog in use at the time of installation of the three main imaging cameras (WFPC2, ACS, and WFC3) and the typical errors at each epoch.
...
