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	2.111	23 56 55.87536	-24 59 47.7816	0600-44794616	359.232814	-24.996606			13.6	13.0	1984.140
2	8.672	23 56 55.31136	-24 59 40.9308	0600-44794538	359.230464	-24.994703			19.9	17.8	1984.140
3	12.902	23 56 55.88016	-24 59 34.8612	0600-44794618	359.232834	-24.993017			19.4	17.9	1984.140

%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	1.95	23 56 55.8624	-24 59 47.256	0698200935	359.23276	-24.99646	0.3	14.25	0.31	0	3	04LQ	1982.635
2	2.19	23 56 55.8816	-24 59 47.724	0698200935	359.23284	-24.99659	0.3	14.51	0.34	0	3	04JK	1977.556

%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	2.00	23 56 55.8672	-24 59 47.400	0698200935	359.23278	-24.99650	0.3	14.27	0.31	0	3	1982.635
2	2.10	23 56 55.8744	-24 59 47.832	0698200935	359.23281	-24.99662	0.3	14.55	0.34	0	3	1977.556

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	2.025	23 56 55.86600	-24 59 47.1300	S322103168	359.232775	-24.996425	1996.686	14.05	0.41	13.78	0.26	3	9.38	0.36
2	8.748	23 56 55.33680	-24 59 40.5600	S32210312391	359.230570	-24.994600	1996.686	18.43	0.44			0	2.68	0.18

%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	2.009	23 56 55.86827	-24 59 47.6510	359.232785	-24.996525	-0.2	-18.4	16.63	0.94		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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