For a basic description of the UCAC-3, see the ReadMe file.

Section 5 of the aforementioned ReadMe file has more information about the individual catalogue fields. The ASCII version of the extracted subset of the UCAC-3 catalogue contains some (or all) of the following fields:

*1) id -*- identification number. This number is unique for each object in the catalogue and is of the form ZZZZ-NNNNNNN. ZZZZ is the 4 digit SPD zone number that the object is in. NNNNNNN is the record number of the object in that zone file.
*2) altid -*- alternate identification number(s). The UCAC3 id is the official UCAC-3 object ID number, and is a unique integer that increases monotonically from the beginning of the catalogue. It is the object record number in the catalogue. A 2MASS cross-identification number is given, if there was a match. The MPOS is a unique internal to UCAC id number.
*3) RA -*- the Right Ascension of the object in hours or degrees. The epoch and equinox are those given in the file header. The default is equinox and epoch J2000.0.
*4) DEC -*- the Declination of the object in degrees. The epoch and equinox are those given in the file header. The default is equinox and epoch J2000.0.
*5) sra -*- the error in the RA position. This is given in integer milli-arcseconds. The error is given at the RA Mean Epoch.
*6) sde -*- the error in the DEC position. This is given in integer milli-arcseconds. The error is given at the DEC Mean Epoch.
*7) sRaEp -*- the error in the RA position at the epoch of the given catalogue position. This is given in integer milli-arcseconds.
*8) sDeEp -*- the error in the DEC position at the epoch of the given catalogue position. This is given in integer milli-arcseconds.
*9) RA Epoch -*- this is the mean epoch of all the observations that went into determining the RA position of this object. This is given in decimal years.
*10) DEC Epoch -*- this is the mean epoch of all the observations that went into determining the DEC position of this object. This is given in decimal years.
*11) MuRa -*- the proper motion in RA. This is given in angular velocity units of milli-arcseconds per year. [This equals MuRA = d(RA)/dt x cos(DEC)]
*12) MuDec -*- the proper motion in DEC. This is given in angular velocity units of milli-arcseconds per year.
*13) sMuRA -*- the error in the proper motion in RA. Given in angular velocity units of milli-arcseconds per year.
*14) sMuDE -*- the error in the proper motion in DEC. Given in angular velocity units of milli-arcseconds per year.
*15) NFitPt -*- the number of observations used in the fit for the position.
*16) Flags -*- this column merges many bits of information. They are indicated as individual bits in this integer. N.B: The value list in this column is given in HEXIDECIMAL.
*17) NObs1 -**18) NObs2 -**19) NObs3 -**20) Vf Magnitude -*- Visual magnitude. This is some sort of V magnitude, based on a PSF fit.
*21) Sigma -*- this gives information related to the photometric uncertainty.
*22) MagFlg -*- this gives information related to the photometric calibration.
*23) S/G -*- this field is the star/galaxy index. This is a measure of the similarity of the detection to a stellar point spread function. This is carries different information depending up on the magnitude. There is a S/G value for each individual magnitude.
*24) Va Magnitude -*- Visual magnitude. This is some sort of V magnitude, based on aperture photometry.
*25) J Magnitude -*- Near IR J magnitude. This is the J magnitude from the 2MASS survey. The valid magnitudes should span -5 to 16 magnitude. The formal valid range is 0.00 to 99.99. A value of 30.00 indicates that NO J magnitude was available for this object.
*26) H Magnitude -*- Near IR H magnitude. This is the H magnitude from the 2MASS survey. The valid magnitudes should span -5 to 16 magnitude. The formal valid range is 0.00 to 99.99. A value of 30.00 indicates that NO H magnitude was available for this object.
*27) Ks Magnitude -*- Near IR Ks magnitude. This is the K magnitude from the 2MASS survey. The valid magnitudes should span -5 to 16 magnitude. The formal valid range is 0.00 to 99.99. A value of 30.00 indicates that NO K magnitude was available for this object.
*28) B -*- blue magnitude. This is the magnitude derived from the POSS plates by the SuperCOSMOS project. The valid magnitudes should span ~0 to ~22 magnitude. The formal valid range is 0.00 to 99.99. This is a PHOTOGRAPHIC B magnitude.
*29) R -*- red magnitude. This is the magnitude derived from the POSS plates by the SuperCOSMOS project. The valid magnitudes should span ~0 to ~22 magnitude. The formal valid range is 0.00 to 99.99. This is a PHOTOGRAPHIC R magnitude.
*30) I -*- near IR magnitude. This is the magnitude derived from the POSS plates by the SuperCOSMOS project. The valid magnitudes should span ~0 to ~22 magnitude. The formal valid range is 0.00 to 99.99. This is a PHOTOGRAPHIC I magnitude.
*31) Xi (computed quantity) -*- the standard coordinate Xi, in the tangent plane projection about the requested region center. This is only computed for rectangular or circular regions. The units are decimal arcseconds.
*32) Eta (computed quantity) -*- the standard coordinate Eta, in the tangent plane projection about the requested region center. This is only computed for rectangular or circular regions. The units are decimal arcseconds.
*33) DistCtr (computed quantity) -*- distance from this object to the extraction center in arcseconds.
*34) Gal_L (computed quantity) -*- computed galactic longitude, in decimal degrees.
*35) Gal_B (computed quantity) -*- computed galactic latitude, in decimal degrees.

Comments, questions, etc., write to S. Levine

Last updated: 08dec2009 by sel