UCAC1 Catalogue

C2A is able to read a compiled version of the UCAC1 catalogue (First U.S. Naval Observatory CCD Astrograph Catalogue). The UCAC1 catalogue, published by the US Naval Observatory, is a high precision high density astrometric catalogue which references around 27 million stars between magnitude 8 and 16 in the Southern hemisphere. It is the first stage in a project to cover the whole sky. The catalogue gives positions, proper motions, errors in position and proper motion, as well as approximate magnitudes. You select the UCAC1 catalogue as the current catalogue through the Stars tab of the Options dialogue box, or by SHIFT-right-clicking on the map.

C2A takes into account the proper motions given in the UCAC1 catalogue in determining star positions at a date specified by the user.

If you have the original UCAC1 catalogue, the Tools page of the C2A Website provides a tool for compiling it in the C2A format. All the information needed to compile the catalogue is given on that page.

The information reported for each star is in the standard format of the UCAC1 catalogue. The description of the fields given in the UCAC1 documentation is provided below.

col format item unit range of values
1-10 I10 RA mas [ 1154 1295999821]
11-20 I10 SPD mas [ 57965 304195851]
21-25 I5 mag 1/100 [ 570 1715]
26-29 I4 sx mas [ 1 200]
30-33 I4 sy mas [ 1 200]
34-36 I3 no [ 2 37]
37-41 I5 ep 1/1000 yr [ 1121 2852]
42-48 I7 pmx 1/10 mas/yr [-18759 65382]
49-55 I7 pmy 1/10 mas/yr [-57756 9936]
56-59 I4 spx 1/10 mas/yr [ 6 347]
60-63 I4 spy 1/10 mas/yr [ 5 310]
64-66 I3 nc [ 2 26]

Further information on the UCAC1 catalogue can be found on the UCAC homepage at:  http://www.usno.navy.mil/USNO/astrometry/optical-IR-prod/ucac.

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