USNO CCD Astrograph Catalog
The USNO CCD Astrograph Catalog (UCAC) is an astrometric star catalog from the United States Naval Observatory .
Versions
UCAC-1
The first preliminary edition, published in March 2000, contains positions and proper motions of over 27 million stars in the southern hemisphere in the magnitude of 8 to 16 mag .
UCAC-2
The second edition was published for the IAU General Assembly in Sydney (2003) and contains positions and movements of about 50 million stars.
UCAC-3
The third edition was published at the IAU General Assembly in Rio (August 2009).
UCAC-4
The fourth edition was published in August 2012.
The first version of the URAT successor catalog has been available since spring 2015 .