2 GSC23 ivo://archive.stsci.edu/gsc/gsc2.3 doi:10.17909/T9VC7T Space Telescope Science Institute Archive Space Telescope Science Institute Catalogs and Surveys Branch 2.3.2 STScI Archive archive@stsci.edu Observational astronomy Surveys The Guide Star Catalog II (GSC-II) is an all-sky optical catalog based on 1" resolution scans of the photographic Sky Survey plates, at two epochs and three bandpasses, from the Palomar and UK Schmidt telescopes. This all-sky catalog will ultimately contains positions, proper motions, classifications, and magnitudes in multiple bandpasses for almost a billion objects down to approximately Jpg=21, Fpg=20. The GSC-II is currently used for HST Bright Object Protection and HST pointing. Looking ahead, the GSC-II will form the basis of the Guide Star Catalog for JWST. This was constructed in collaboration with ground-based observatories for use with the GEMINI, VLT and GALILEO telescopes http://gsss.stsci.edu/Catalogs/GSC/GSC2/GSC2.htm Catalog Research 2 http://gsss.stsci.edu/webservices/vo/ConeSearch.aspx?CAT=GSC23& GET 1 1000 false 21 42 0.01 Optical