Note: USNO-A2.0 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 () and collaborators at 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.

Full	_r arcsec	_RAJ2000 "h:m:s"	_DEJ2000 "d:m:s"	USNO-A2.0	RAJ2000 deg	DEJ2000 deg	ACTflag	Mflag	Bmag mag	Rmag mag	Epoch yr
1	1.076	13 25 39.54552	-20 46 44.4612	0675-12615857	201.414773	-20.779017			18.2	17.7	1953.357
2	1.633	13 25 39.47736	-20 46 45.2532	0675-12615847	201.414489	-20.779237			15.5	16.3	1980.814

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Full	_r arcsec	_RAJ2000 "h:m:s"	_DEJ2000 "d:m:s"	GSC2.2	RA(ICRS) deg	DE(ICRS) deg	Epoch yr	Rmag mag	e_ mag	Bjmag mag	e_ mag	Class	a pix	e
1	1.331	13 25 39.43896	-20 46 44.7060	S20303304910	201.414329	-20.779085	1993.214	17.28	0.41	16.52	0.27	3	5.67	0.14

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Full	_r [****ClosingBrace(s)Inserted****]
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