contains 526,280,881 sources, and is based on a
re-reduction of the Precision Measuring Machine (PMM) scans
from POSS-I O and E plates (>=-18°) and SRC-J and
ESO-R plates (<=-20°).
USNO-A2.0 was created by Dave Monet (Flagstaff Station, U.S. Naval Observatory.
The major difference between USNO-A2.0 and its previous version
USNO-A1.0 is that A1.0 used the
Guide Star Catalog as its reference frame whereas
A2.0 uses the ICRF as realized by the
USNO ACT catalog (Urban et al. 1997).
The VizieR search engine uses an
on-line compressed version
(3.6Gbytes) which was generated at CDS.
Note: The Guide Star Catalog has been constructed to support the
operational need of the Hubble Space Telescope.
It contains over 25 million positions for about 19 million
objects, of which more than 15 million are classified as stars.
The version 1.2 is a new astrometric reduction which results in
absolute position errors about 0.3-0.4 arcsec.
(see GSC pages at URL http://www-gsss.stsci.edu/gsc/gsc.html)
Note: The construction of the
is still in progress: this
version has no proper motions, and the magnitude limits are 18.5 in F (red)
and 19.5 in J (blue). The data are copyrighted, check
the data use Policy.
Note: the J2000 coordinates are not part of the original catalogue; their accuracy can be low, see the CooFlag column
Note: This version of the
has no proper motions, but the limits on brightness which existed on
GSC2.2 (F<18.5, Bj<19.5) were removed.
Note: The limiting magnitude is about 15.2 in the GSC photometric system.
Note: see the UCAC4 document, and the
the fix for high proper motion stars.
The UCAC home page is available at
Please acknowledge the usage
of the UCAC4
Note: Zone -40/+50deg
Note: UCAC5 document
(original column names in green) (1692919135 rows)
Note: please credit the usage of the UKIDSS data (details at http://www.ukidss.org/archive/archive.html)
Note: Many errors detected in the positions given in the catalogue, especially in the sign of the declination in the zones -1°<δ<+1°
Note: SDSS is also available from http://www.sdss3.org/dr9/
Note: Errors found in the Final IUE Merged log are reported in the file errata.htx
Note: (see also the postcard server)
Note: The ``short'' version of the catalogue can be retrieved by a selecting *+* in the SEQflags column
Note: The column expnum provides an access to details on the exposures, and a link to the Preview and Retrieval System via the CADC
Note: Details of surveyed literature