USNO CCD Astrograph Catalog
The USNO CCD Astrograph Catalog is an astrometric star catalog of the United States Naval Observatory.UCAC-1
The first preliminary edition, published in March 2000, gives the positions and proper motions of over 27 million stars in the southern hemisphere in the brightness range 8-16.UCAC-2
The second issue was the IAU published General Assembly in Sydney and includes positions and proper motions of about 50 million stars.UCAC-3
The third edition was published in the IAU General Assembly in Rio.UCAC-4
The fourth edition was published in August 2012.
Since Spring 2015, the successor URAT is available.UCAC-5
The fifth edition was published in February 2017.