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	0.583	00 48 56.75016	-01 27 02.5308	0825-00183934	012.236459	-01.450703			16.3	14.9	1954.674

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Full	_r arcsec	_RAJ2000 "h:m:s"	_DEJ2000 "d:m:s"	ACR	RAJ2000 deg	e_ mas	DEJ2000 deg	e_ mas	RFmag mag	pmRA s/hyr	e_ mas/yr	pmDE arcsec/hyr	e_ mas/yr
1	0.242	00 48 56.73696	-01 27 03.1074	1011042	012.236409	32	-01.450849	31	16.29	-0.028	5.9	-1.23	5.9

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Full	_r arcsec	_RAJ2000 "h:m:s"	_DEJ2000 [****ClosingBrace(s)Inserted****]
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