The HST Guide Star Catalog, Version 1.2

This catalog provides positions and magnitudes for these stars. The original version of this catalog, GSC 1.0, is described in a series of papers: Lasker et al. (1990AJ.....99.2019L); Russell et al. (1990AJ.....99.2059R); and Jenkner et al. (1990AJ.....99.2082J) The reference material for the GSC 1.2 reduction is the "Positions and Proper Motions Catalogue": PPM-North, Roeser S. and Bastian U., 1988, Cat. <I/146> PPM-South, Bastian U. and Roeser S., 1993, Cat. <I/193> PPM-Suppl, Roeser S., Bastian U. and Kuzmin A., 1994, Cat. <I/208> and the Astrographic Catalogue (AC) which was used to remove the mean systematics common to all the plates.

The overall rms error of the GSC 1.2 is estimated better than 0.3arcsec The STScI provides the details of the GSC versions ("See also" section below) A binary version of the GSC1.2, with C code for querying, is available in the subdirectory GSC.