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Session 16 - Astrometry.
Display session, Wednesday, January 07
Exhibit Hall,
The USNO-A1.0 catalog (Monet et al. 1996; 10 CD-ROMs; USNO) contains astrometric and photometric information for 488,006,860 objects. Since its compilation, many areas for improvement have been identified. This paper presents a progress report on the implementation of these improvements and discusses the schedule for the compilation of USNO-A2.0. The most significant improvement will be the incorporation of the International Celestial Reference Frame through the adoption of the ACT Catalog (Urban et al. in preparation; CD-ROM; USNO). (The ACT uses data from the Astrographic Catalog to compute proper motions for stars found in the Hipparcos and Tycho catalogs.) In addition to providing the realization of the astrometric reference frame, the ACT catalog contains a high enough source density to allow for a GSC-free derivation of the systematic components of the astrometric distortions found in the Schmidt telescopes that took the survey plates, and for a determination of the magnitude terms for the Palomar Schmidt using the data from the scans of the UJ plates. Other topics include the development of a numerical refocusing technique to improve the quality of existing scans, and the lessons being learned from the scanning of the Lick Northern Proper Motion survey plates.
