(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
188.8.131.524 in January 2010 and it has been in use at Great Shefford since
7th January 2010. A number of improvements have been made to the UCAC-2
here) including extending the coverage to the entire sky.
UCAC-3 is the most accurate general astrometric
catalogue available at the moment, with positional errors better than
0.1" and is used at Great Shefford for all reductions.
(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 184.108.40.2065 with support for the new
UCAC2 did not cover the entire sky, but extended from the south pole
to about +45° declination. See
a plot of the coverage from the USNO.
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
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 is currently only available
by downloading small parts over the web from http://www.nofs.navy.mil/data/FchPix/
. Astrometrica can use this catalogue directly. It is significantly more
USNO SA2.0 is used on occasion when fast preliminary reductions are
required (at about 650Mb this catalogue fits easily on a hard drive).
Normally positions would be re-reduced using UCAC-3 before reporting.
The Hubble telescope GSC 1.1 is used for telescope position
synchronisation by Pinpoint from within Maxim DL/CCD during observing