1255 I/255 The HST Guide Star Catalog, Version GSC-ACT B M Lasker J N Russel H Jenkner The Association of Universities for Research in Astronomy, Inc. ([c] 1989 1992 1996 1990AJ.....99.2019L B M Lasker C R Sturch B J McLean J L Russell H Jenkner M M Shara Astron. J. 99 2019 1990 1990AJ.....99.2019L J L Russell B M Lasker B J McLean C R Sturch H Jenkner Astron. J. 99 2059-2081 1990 1990AJ.....99.2059R H Jenkner B M Lasker C R Sturch B J McLean M M Shara J L Russell Astron. J. 99 2082 1990 1990AJ.....99.2082J I/220 : The HST Guide Star Catalog, Version 1.1 (Lasker+ 1992) I/254 : The HST Guide Star Catalog, Version 1.2 (Lasker+ 1992) I/239 : The Hipparcos and Tycho Catalogues (ESA 1997) I/246 : The ACT Reference Catalog (Urban+ 1997) I/250 : The Tycho Reference Catalogue (Hog+ 1998) http://www-gsss.stsci.edu/gsc/gsc.html : GSC pages at STScI http://www.projectpluto.com/gsc_act.htm : GSC-ACT Original Description Surveys Positional data 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, 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 GSC GSC-ACT is a recalibration of GSC1.1 using the ACT (Astrographic Catalog/Tycho, catalog <I/246>) performed by the Project Pluto ("See also" section below). The "plate RMS" values are given at http://www.projectpluto.com/results.txt, with most plates coming in at under .3 arcseconds

GSC GSC designation the GSC Identification is made of a plate number (5 digits) and star number on the plate (5 digits); note that, in the literature, a dash separates generally the two parts. --- RAdeg Right ascension in J2000, epoch of plate deg DEdeg Declination in J2000, epoch of plate deg PosErr Mean error on position arcsec Pmag photographic magnitude (see n_Pmag) mag e_Pmag photographic magnitude mag n_Pmag Coded passband for magnitude the number designates the following combination of emulsion and filter: magband emulsion filter Notes ------- -------- -------- ----------------------- 0 IIIaJ GG395 SERC-J/EJ 1 IIaD W12 Pal Quick-V 3 --- B Johnson 4 --- V Johnson 5 IIIaF RG630 Red 6 IIaD GG495 Pal QV/AAO XV 7 103aO --- POSS-I Blue 8 103aE red plex POSS-I Red 10 IIaD GG495 GPO Astrograph 11 103aO GG400 Black Birch Astrograph 16 IIIaJ GG495 QV 18 IIIaJ GG385 POSS-II Blue ------- -------- -------- --- Class Class of object (0=star; 3=non-stellar) --- Plate Plate designation two plates (+056 and +017) represent data from catalogues (mainly Hipparcos Input Catalogue, Cat. <I/196>). They have no associated epoch. --- Epoch Epoch of plate yr Mult True if multiple object / False otherwise --- Bill Gray Project Pluto Francois Ochsenbein CDS 1999Sep15 I_255.xml