The USNO CCD Astrograph Catalog (UCAC) is an astrometric star catalog of the United States Naval Observatory.

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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.

The second issue was the IAU published General Assembly in Sydney (2003) and includes positions and proper motions of about 50 million stars.

The third edition was published in the IAU General Assembly in Rio (August 2009).

The fourth edition was published in August 2012.

Since Spring 2015, the successor URAT is available.

The fifth edition was published in February 2017.^[1][2]