C2A is able to read the First U.S. Naval Observatory (USNO) Astrometric Robotic Telescope Catalog, URAT1.
Per the documentation, this catalogue covers most of the northern hemisphere and in some areas as far south as -24.8 deg Dec (Pluto field). It covers the about R = 3 to 18.5 magnitude range with positional precisions of 5 to 40 mas depending on observing history and brightness of stars. It was constructed from 2 years of operations of the astrograph at the Naval Observatory Flagstaff Station (NOFS). URAT1 is supplemented by preliminary proper motions derived exclusively from 2-epoch URAT1 and Two Micron All Sky Survey (2MASS) data (at around epoch 2000) resulting in proper motion errors of typically 5 to 8 mas/yr.
The catalogue contains 228 millions objects (mostly stars) of which 188 million are common to 2MASS. It is not necessary to compile the catalogue, C2A can read it natively.
You select this catalogue as the current catalogue through the Stars tab of the Options dialogue box, or by SHIFT-right-clicking on the map. You can choose to display either of the available magnitude bands by clicking the Advanced options... button on the Stars tab of the Options dialogue box.
Information associated with each object of the catalogue is made of all the data fields from the original catalogue:
column item type unit description notes
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1 ra I*4 mas mean RA on ICRF at URAT mean obs.epoch ( 1)
2 spd I*4 mas mean South Pole Distance = Dec + 90 deg ( 1)
3 sigs I*2 mas position error per coord. from scatter ( 2)
4 sigm I*2 mas position error per coord. from model ( 2)
5 nst I*1 -- tot. number of sets the star is in ( 3)
6 nsu I*1 -- n. of sets used for mean position + flag ( 3)
7 epoc I*2 myr mean URAT obs. epoch - 2000.0 ( 1)
8 mmag I*2 mmag mean URAT model fit magnitude ( 4)
9 sigp I*2 mmag URAT photometry error ( 5)
10 nsm I*1 -- number of sets used for URAT magnitude ( 3)
11 ref I*1 -- largest reference star flag ( 6)
12 nit I*2 -- total number of images (observations)
13 niu I*2 -- number of images used for mean position
14 ngt I*1 -- total number of 1st order grating obs.
15 ngu I*1 -- number of 1st order grating positions used
16 pmr I*2 0.1mas/yr proper motion RA*cosDec (from 2MASS) ( 7)
17 pmd I*2 0.1mas/yr proper motion Dec ( 7)
18 pme I*2 0.1mas/yr proper motion error per coordinate ( 8)
19 mf2 I*1 -- match flag URAT with 2MASS ( 9)
20 mfa I*1 -- match flag URAT with APASS ( 9)
21 id2 I*4 -- unique 2MASS star identification number
22 jmag I*2 mmag 2MASS J mag
23 hmag I*2 mmag 2MASS H mag
24 kmag I*2 mmag 2MASS K mag
25 ejmag I*2 mmag error 2MASS J mag
26 ehmag I*2 mmag error 2MASS H mag
27 ekmag I*2 mmag error 2MASS K mag
28 iccj I*1 -- CC flag 2MASS J (10)
29 icch I*1 -- CC flag 2MASS H
30 icck I*1 -- CC flag 2MASS K
31 phqj I*1 -- photometry quality flag 2MASS J (10)
32 phqh I*1 -- photometry quality flag 2MASS H
33 phqk I*1 -- photometry quality flag 2MASS K
34 abm I*2 mmag APASS B mag (11)
35 avm I*2 mmag APASS V mag
36 agm I*2 mmag APASS g mag
37 arm I*2 mmag APASS r mag
38 aim I*2 mmag APASS i mag
39 ebm I*2 mmag error APASS B mag
40 evm I*2 mmag error APASS V mag
41 egm I*2 mmag error APASS g mag
42 erm I*2 mmag error APASS r mag
43 eim I*2 mmag error APASS i mag
44 ann I*1 -- APASS numb. of nights (12)
45 ano I*1 -- APASS numb. of observ. (12)
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80 = total number of bytes per star record