A METHOD TO IMPROVE GUIDE STAR CATALOG POSITIONS WITH ASTROMETRIC CATALOGS

We discuss a method to obtain on local areas in the sky, precise posit ions for the stars of the Guide Star Catalogue (GSC), referred to the more precise catalogues Carlsberg Meridian Catalogue (CAMC), PPM, and ACRS. The corrections to the right ascensions and declinations are car ried out in the tangent plane in a fashion similar to that of standard photographic astrometry. To test the method, we used the corrected GS C star coordinates as reference frames to reduce and compare extragala ctic radiosource positions, using sky fields obtained from CCD observa tions and from the Digitized Sky Survey of STScI. (C) 1997 American As tronomical Society.