USNO-SA 2.0 Astrometric Reference Catalog

WCSTools Catalogs
The U.S. Naval Observatory SA2.0 is a catalog of 55,368,239 sources intended to provide a grid of astrometric reference objects over the whole sky. It is a spatially sub-sampled version of USNO-A2.0 Catalog and provides an astrometric reference catalog for asteroid hunters and other folks who do not need all of that 11-CDROM, 526,280,881-source catalog. The format is the same as USNO-A2.0.


This catalog is available via anonymous ftp from For susa2, you need only the files ending in .cat.

This catalog used to be distributed on a single CD-ROM obtained by a request made via, which now reads,
"This catalog is no longer available for distribution."

Catalog access software in C for Unix systems has been written by Doug Mink at the Harvard-Smithsonian Center for Astrophysics.

[WCSTools UAC Programs] [susa2] [imusa2] [USNO-SA1.0] [USNO-A2.0 format] [A2.0 from USNO]