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	3.130	12 35 40.19280	-37 11 34.1124	0525-15240730	188.917470	-37.192809			13.3	12.8	1979.841
2	7.309	12 35 39.76488	-37 11 33.3420	0525-15240616	188.915687	-37.192595			18.0	17.5	1979.841

%0a%0a%3cP%3e%0a%3cFONT%20SIZE=%27-1%27%3e%3cEM%3e%3cFONT%20COLOR=%27#0000FF%27>%3cB%3eNote:%20The%20%3cB%3eGuide%20Star%20Catalog%20has%20been%20constructed%20to%20support%20the%20%0aoperational%20need%20of%20the%20Hubble%20Space%20Telescope.%0aIt%20contains%20over%2025%20million%20positions%20for%20about%2019%20million%0aobjects,%20of%20which%20more%20than%2015%20million%20are%20classified%20as%20stars.%0aThe%20version%20%3cB%3e1.2%20is%20a%20new%20astrometric%20reduction%20which%20results%20in%0aabsolute%20position%20errors%20about%200.3-0.4%20arcsec.%0a%28see%20GSC%20pages%20at%20URL%20http://www-gsss.stsci.edu/gsc/gsc.html%29%0a%3cP%3e%0a

Full	_r arcsec	_RAJ2000 "h:m:s"	_DEJ2000 "d:m:s"	GSC	RAJ2000 deg	DEJ2000 deg	PosErr arcsec	Pmag mag	e_ mag	n_	Class	Plate	Epoch yr
1	2.45	12 35 40.2984	-37 11 34.548	0724600202	188.91791	-37.19293	0.5	13.96	0.40	0	3	00ZD	1982.371
2	2.59	12 35 40.3008	-37 11 34.404	0724600202	188.91792	-37.19289	0.6	14.46	0.40	0	3	04HH	1976.408
3	2.91	12 35 40.2600	-37 11 34.116	0724600202	188.91775	-37.19281	0.3	13.34	0.40	0	3	04HG	1975.420

%0a%0a%3cP%3e%0a%3cFONT%20SIZE=%27-1%27%3e%3cEM%3e%3cFONT%20COLOR=%27#0000FF%27>%3cB%3eNote:%20The%20%3cB%3eGSC-ACT%20%3cEM%3e%28or%20%3cB%3eGSC1.3%29%0ais%20a%20recalibration%20of%20the%20%3cB%3e<%25E%20I/220%7cGSC1.1>,%20the%20catalogue%20constructed%20%0ato%20support%20the%20operational%20need%20of%20the%20Hubble%20Space%20Telescope,%0awith%20the%20%3cB%3e<%25E%20I/246%7cACT>,%20the%20combination%20of%20the%20Astrographic%20Catalogue%0aand%20the%20%3cB%3e%3cEM%3eTycho%20catalogue%20derived%20from%20the%20%3cEM%3e<%25E%20I/239%7cHipparcos>%0amission;%20see%20http://www.projectpluto.com/gsc_act.htm%20for%20more%20details%0aabout%20this%20recalibration.%0a%3cP%3e%0a%22>

>	\BegDIVclass='sort-down ' </A>
dec Full	_r arcsec	_RAJ2000 "h:m:s"	_DEJ2000 "d:m:s"	GSC	RAJ2000 deg	DEJ2000 deg	PosErr arcsec	Pmag mag	e_ mag	n_	Class	Epoch yr
1	2.63	12 35 40.2576	-37 11 34.404	0724600202	188.91774	-37.19289	0.5	13.97	0.41	0	3	1982.371
2	3.06	12 35 40.2888	-37 11 33.936	0724600202	188.91787	-37.19276	0.6	14.47	0.41	0	3	1976.408
3	3.24	12 35 40.2384	-37 11 33.828	0724600202	188.91766	-37.19273	0.3	13.37	0.40	0	3	1975.420

Note: The construction of the GSC-II 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.

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	3.614	12 35 40.25040	-37 11 33.4212	S201013094	188.917710	-37.192617	1991.342	14.23	0.42	13.17	0.41	3	7.37	0.42

%0a%0a

Full	_r arcsec	_RAJ2000 "h:m:s"	_DEJ2000 "d:m:s"	RA(ICRS) deg	DE(ICRS) deg	pmRA mas/yr	pmDE mas/yr	Vmag mag	B-V mag	F1	F2	F3
1	3.470	12 35 40.27752	-37 11 33.4502	188.917805	-37.192649	5.9	9.8	16.39	0.23		G

%0a%0a%3cP%3e%0a%3cFONT%20SIZE=%27-1%27%3e%3cEM%3e%3cFONT%20COLOR=%27#0000FF%27>%3cB%3eNote:%20The%20%3cB%3eUSNO-B%20Catalog%20presents%20positions,%20proper%20motions,%20%0amagnitudes%20un%20blue,%20red%20and%20infrared,%20as%20well%20as%20star/galaxy%20estimators%0afor%201,045,175,762%20objects%20derived%20from%203,648,832,040%20separate%20observations.%0aThe%20data%20were%20taken%20from%20scans%20of%207,435%20Schmidt%20plates%0ataken%20from%20various%20sky%20surveys%20during%20the%20last%2050%20years.%3cBR%3e%0aUSNO-B1.0%20catalog%20was%20created%20by%20Dave%20Monet%20and%20collaborators%0aat%20http://www.nofs.navy.mil/data/fchpix/%20%3cBR%3e%0a%3cB%3e%3cFONT%20COLOR=%27#EE0000%27>%20Note%20that%20the%20star/galaxy%20estimators%20may%20be%20mixed%20up%0a%20in%20dense%20regions.%0a%3cP%3e%0a

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