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D. G. Monet (U.S. Naval Observatory Flagstaff Station)
The USNO-B catalog is the extension of the USNO-A catalog that includes proper motions and star/galaxy classifications. The task of compiling this catalog is difficult because the centers of the POSS-I and POSS-II surveys are different (6-degree vs. 5-degree), and this means that the errors of the astrometric solutions that unbend the Schmidt plates must be well understood and small. To verify the reduction algorithms, the Yellow Sky (YS) catalog is being prepared. This is being compiled from the yellow exposures taken as part of the Lick Northern Proper Motion (NPM) Survey and the Yale/San Juan Southern Proper Motion (SPM) Survey. Since the systematic errors of the astrographs and Schmidt telescopes are expected to be quite different, the intercomparison of the YS catalog and the Schmidt plate solutions should provide the best available test of astrometric accuracy. This paper will discuss the compilation of the intermediate catalogs and present some of the intercomparisons. There are no plans for the public release of YS as a separate catalog. Access to the NPM and SPM plates has been provided through the kindness of the astrometric groups at the Lick and Yale observatories, and all plates have been digitized and reduced by the U.S. Naval Observatory's Precision Measuring Machine (PMM).