The Second HST Guide Star Photometric Catalog

Abstract

The second generation Hubble Space Telescope Guide Star catalog (GSC-II) is currently under construction. GSC-II will include both stars and galaxies down to the plate limits of the 1950 POSS E plates and the SERC J plates (V ≈ 21). In addition, multi-bandpass and multi-epoch data will be added as current epoch surveys in both hemispheres become available in digitized format. In order to provide accurate photometric calibration for GSC-II, the Space Telescope Science Institute is extending the BV photoelectric photometry in the Guide Star Photometric Catalog (GSPC-I) to a fainter V band limit and adding R band data. The new catalog, hereafter GSPC-II, will have 5% photometry in the V and R passbands to a limiting magnitude of V = 21. The survey is being conducted using CCD direct imaging cameras at observatories in both the northern and southern hemispheres (see Table 1).