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	0.709	22 53 31.42152	+00 48 25.5204	0900-20261484	343.380923	+00.807089			16.8	16.0	1953.912

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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	0.465	22 53 31.40693	+00 48 25.3523	16025950	343.380867	34	+00.807046	36	16.68	-0.030	5.8	-0.36	5.8

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