The Guide Star Catalog (GSC), which has been constructed to support
the operational need of the Hubble Space Telescope contains nearly 19
million objects brighter than sixteenth magnitude, of which more than
15 million are classified as stars. 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
PPM-South, Bastian U. and Roeser S., 1993
PPM-Suppl, Roeser S., Bastian U. and Kuzmin A., 1994
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
