PMM Catalogs

USNO-B1.0 is the latest catalogue from the USNOFS PMM project. It contains over 1,000,000,000 entries and has positions, magnitudes and proper motions for each object. The catalogue is over 80 GBytes in size; because of its large size, we do not currently have plans to print copies for distribution. As computer media evolve, this may change. At this time, data from this catalogue can be obtained from the USNO Image and Catalogue Server.

USNO-A2.0 contains entries for over a half billion stars (526,230,881, to be exact!) which were detected in the digitized images of three photographic sky surveys. For the entire northern sky and the southern sky down to declinations of -30°, all the photographic plates were part of the original Palomar Optical Sky Survey (POSS-I). Photographs were taken on blue- and red-sensitive emulsions. Only those stars which were detected in both colors were included in the USNO-A2.0 catalog. The rest of the southern sky was covered by the Science Research Council (SRC)-J survey and the European Southern Observatory (ESO)-R survey. Again, only stars appearing in both colors were accepted for the final catalogue.

Obtaining a copy.

USNO-SA2.0 is a subset of USNO-A2.0 which is a lot easier to handle on a small computer because it contains only a tenth as many stars as the parent catalog (54,787,624 stars in all). The goal in creating this smaller catalog was to provide a spatially uniform distribution of stars in an intermediate range of magnitudes which would be useful as a ``reference grid'' for astrometric analysis.

Obtaining a copy.

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