AAS 196th Meeting, June 2000
Session 53. Surveys, Catalogs, Database
Display, Thursday, June 8, 2000, 9:20am-4:00pm, Empire Hall South

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[53.03] The first US Naval Observatory CCD Astrograph Catalog

M. E. Germain, N. Zacharias, S. E. Urban, T. J. Rafferty, E. R. Holdenried (U.S. Naval Observatory), M. I. Zacharias (Universities Space Research Association), D. M. Hall, G. L. Wycoff, D. G. Monet (U.S. Naval Observatory)

The USNO CCD Astrograph Catalog (UCAC) project is a high precision, astrometric survey of stars having R magnitudes between 7th and 16th. The positional accuracy is 20 mas for stars between 9th and 14th, and 70 mas for fainter stars. This gives a density (stars per square degree) higher than that of the Guide Star Catalog (GSC), with an improvement in positional accuracy of about a factor of ten. Observations began in January 1998 at Cerro Tololo Inter--American Observatory (CTIO) using a five-element 0.2 meter astrograph equipped with a 4k by 4k CCD. The instrument will be moved north in early 2001, and full sky coverage is expected by early 2003.

A preliminary catalog (UCAC1) of positions and proper motions of 27 million stars has been constructed which is available on CD-ROM from USNO. Observations between 13 Feb 1998 and 07 Nov 1999 are included with a total of over 79,000 CCD frames covering 80% of the Southern Hemisphere. The catalog is on the International Celestial Reference System (ICRS), which is consistent with J2000. Proper motions of bright stars (V <= 12.5) were derived using a combination of ground-based astrometric catalogs, Hipparcos, and Tycho-2 positions, giving a typical error of 3 mas/yr. For the fainter stars the USNO A2.0 (Monet, 1998) was used as first epoch, with typical proper motion errors of 10 to 15 mas/yr. External comparisons with Tycho-2 and the Yale Southern Proper Motion (SPM) 2.0 data reveal systematic errors to be only on the 10 mas level.

The author(s) of this abstract have provided an email address for comments about the abstract: nz@usno.navy.mil

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