11.0. In total, over 4.6 million stars were observed, many as faint as 13th magnitude. This project was started in the late 19th century. The observations were made between 1891 and 1950. To observe the entire celestial sphere without burdening too many institutions, the sky was divided among 20 observatories, by declination zones. Each observatory exposed and measured the plates of its zone, using a standardized telescope (a "normal astrograph") so each plate photographed had a similar scale of approximately 60 arcsecs/mm. The U.S. Naval Observatory took over custody of the catalogue, now in its 2000.2 edition. BS, BSC, HR First published in 1930 as the Yale Catalog of Bright Stars, this catalogue contained information on all stars brighter than visual magnitude 6.5 in the Harvard Revised Photometry Catalogue. The list was revised in 1983 with the publication of a supplement that listed additional stars down to magnitude 7.1. The catalogue detailed each star's coordinates, proper motions, photometric data, spectral types, and other useful information. The last printed version of the Bright Star Catalogue was the 4th revised edition, released in 1982. The 5th edition is in electronic form and is available online. SAO The Smithsonian Astrophysical Observatory catalogue was compiled in 1966 from various previous astrometric catalogues, and contains only the stars to about ninth magnitude for which accurate proper motions were known. There is considerable overlap with the Henry Draper catalogue, but any star lacking motion data at that time is omitted. The epoch for the position measurements in the latest edition is J2000.0. The SAO catalogue contains this major piece of information not in Draper, the proper motion of the stars, so it is often used when that fact is of importance. The cross-references with the Draper and Durchmusterung catalogue numbers in the latest edition are also useful. Names in the SAO catalogue start with the letters SAO, followed by a number. The numbers are assigned following 18 ten-degree bands in the sky, with stars sorted by right ascension within each band. USNO-B1.0 USNO-B1.0 is an all-sky catalogue created by research and operations astrophysicists at the U.S. Naval Observatory (as developed at the United States Naval Observatory Flagstaff Station), that presents positions, proper motions, magnitudes in various optical passbands, and star/galaxy estimators for 1,042,618,261 objects derived from 3,643,201,733 separate observations. The data was obtained from scans of 7,435 Schmidt plates taken for the various sky surveys during