The First U.S. Naval Observatory Robotic Astrometric Telescope Catalog
US Naval Observatory Washington United States
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URAT1 is an observational, astrometric catalog covering most of the slant -15 area and a magnitude range of about R 3-18.5. Accurate positions typically 10-30 mas standard error are given for over 228 million objects at a mean epoch around 2013.5. For the over 188 million objects matched with the Two Micron All Sky Survey 2MASS point-source catalog proper motions typically 5-7 mas yr-1 standard errors are provided. These data are supplemented by 2MASS and AAVSO Photometric All-Sky Survey APASS photometry. Observations, reductions, and catalog construction are described, together with results from external data verifications. The catalog data are served by CDS, Strasbourg I329.