An all-sky catalogue of positions and proper motions of stars between 8th and 16th magnitudes produced by the US Naval Observatory; proper motions are derived by reference to older catalogues. Observations of the southern hemisphere were made at Cerro Tololo Inter-American Observatory in Chile with a 0.2-m astrograph in 1998–2001. The telescope was then moved to the US Naval Observatory's Flagstaff Station in Arizona to observe the northern sky. Intermediate data releases, UCAC1 and UCAC2, were made in 2000 and 2003. Observations ended in 2004; the final catalogue (UCAC3), containing over 100 million stars, was published in 2009.
http://www.usno.navy.mil/USNO/astrometry/optical-IR-prod/ucac Official catalogue web page.
Subjects: Astronomy and Astrophysics.