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 current version includes only the North (POSS-I plates)
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: 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: 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: UCAC5 document
(original column names in green) (1692919135 rows)
(original column names in green) (1811709771 rows)
© Université de Strasbourg/CNRS