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		UCAC-3
        (The Third US Naval Observatory CCD Astrograph Catalog) was released on 
		a double sided DVD containing 8Gb of binary files during September 2009. 
		Herbert Raab added support for UCAC-3 to Astrometrica in version 
		4.6.1.384 in January 2010 and  was used at Great Shefford from 7th 
		January 2010 until February 2013 when support for UCAC-4 was made 
		available. A number of improvements were made to the UCAC-2 catalogue including extending the coverage to the entire sky. 
         UCAC-2
        (The Second US Naval Observatory CCD Astrograph Catalog) was released on
        three CDs by the USNO at the end of July 2003 and the CDs were received
        at Great Shefford a week or so later. By 19 Aug 2003 Herbert Raab had
        issued Astrometrica version 4.3.0.325 with support for the new
        catalogue. UCAC2 did not cover the entire sky, but extended from the south pole 
		to about +45° declination.  UCAC2 was used at Great Shefford for all reductions within its
        coverage.  Outside of this area USNO B1.0 was used (see below). Magnitudes derived from measures using UCAC2 have been found to be
        about 0.5 mags fainter than the equivalent using the USNO A2 or B1
        catalogues.  USNO B1.0 was used at Great Shefford from 2003 March until 2003
        August for all reductions reported
        to the MPC wherever possible. This catalogue was currently only available
        by downloading small parts over the web from http://www.nofs.navy.mil/data/FchPix/
        . Astrometrica can use this catalogue directly. 
		USNO A2.0 contains 526 million stars and is used for telescope position
        synchronisation by Pinpoint from within Maxim DL/CCD during observing
        runs. It is obsolete for astrometric purposes as it does not include 
		stellar proper motion information but at 5.9Gb is easily held on a hard 
		disk and has good all-sky coverage. |