Placing Schmidt Astrometry on The ICRS

Abstract

The sky-limited, large-area photographic surveys which are being used for the construction of the second generation Guide Star Catalog (GSC-II) will be for many years to come the largest astronomical database available. The survey plates are typically placed on a 5-degree grid, with each plate area of about 42 square degrees, for a total of more than 1700 plates covering the whole sky. The expected data volume is about 2 Tbytes per bandpass. The final product will consist of an all-sky catalog of positions, proper motions, magnitudes and at least one color to a minimum of V=18. Among the scientific motivations behind such an endeavor let us mention operation of ground-based telescopes and future space missions, observation planning, statistical investigations (see, e.g., Lasker et al. 1995, Cannon 1997)