The FIRST Survey Catalog: 13Jun05 Version

A catalog for the north and south Galactic caps (971,268 sources), derived from the 1993 through 2011 observations, is available as a gzip-compressed ASCII file (catalog_13jun05.bin.gz) and as a FITS binary table (first_13jun05.fits.gz). The file size is 42 MBytes compressed (160 MBytes uncompressed) for the ASCII version and 62 MBytes compressed (97 MBytes uncompressed) for the FITS version. The catalog covers a total of about 10,635 square degrees of sky (8,444 square degrees in the north Galactic cap and 2,191 square degrees in the south Galactic cap.)

See the coverage maps for more details of the area covered. Both the northern and southern areas were chosen to coincide approximately with the area covered by the Sloan Digital Sky Survey.

The area covered is almost identical to the previous version of the catalog; however, many images (particularly in the southern area) have been reprocessed with improved algorithms that have reduced noise and sidelobe levels. Consequently this catalog includes about 25,000 more sources than the previous version.

Over most of the survey area, the detection limit is 1 mJy. A region along the equatorial strip (RA = 21.3 to 3.3 hrs, Dec = -1 to 1 deg) has a deeper detection threshold because two epochs of observation were combined. The typical detection threshold in this region is 0.75 mJy. There are approximately 4,500 sources below the 1 mJy threshold used for most previous versions of the catalog.

EVLA calibration error: In the areas observed using the new EVLA configuration (see the observation status description for details), there is currently a small flux calibration error that affects the catalog flux density measurements for some sources in the south Galactic cap. Affected sources have observation epochs later than 2011. We estimate that for most sources the calibration error is smaller than 3%, although a few percent of the sources have flux density errors as large as 8%. We will release a new version of the catalog that corrects this problem.

The catalog is on-line and can be searched using the FIRST Search Engine. However, for large-scale investigations it will be necessary to obtain the complete catalog. This document describes the catalog format.

The catalog is sorted by decreasing declination and has the following format:

#                                                                                                               ------SDSS------ -----2MASS----  Epoch     Epoch     Epoch  
#  RA           Dec        P(S)    Fpeak      Fint    RMS     Maj    Min   PA    fMaj   fMin   fPA Field         #  Sep    i  Cl  #  Sep    K   Mean-yr   Mean-MJD   rms-MJD
07 27 34.289 +64 40 59.80 0.197     1.00      1.12   0.139   2.13   1.58   0.2   5.80   5.63   0.2 07300+64243J -1 99.00 99.00 -  1  6.76 14.62 2002.687 2452526.1     0.002
07 38 39.304 +64 40 16.28 0.014     2.39      5.73   0.139   9.31   3.58 136.6  10.76   6.48 136.6 07360+64243J -1 99.00 99.00 -  0 99.00 99.00 2002.687 2452526.1     0.001
07 50 24.019 +64 40 01.21 0.014    22.09     24.00   0.140   1.96   1.13   6.8   5.74   5.52   6.8 07480+64243J -1 99.00 99.00 -  0 99.00 99.00 2002.687 2452526.1     0.002
07 38 45.622 +64 39 50.12 0.014     2.39      4.33   0.140   6.43   3.27  13.5   8.40   6.31  13.5 07360+64243J -1 99.00 99.00 -  0 99.00 99.00 2002.687 2452526.1     0.000
07 39 32.799 +64 39 18.03 0.082     1.41      1.25   0.139   2.63   0.00  37.5   6.01   4.30  37.5 07420+64243J -1 99.00 99.00 -  0 99.00 99.00 2002.687 2452526.1     0.002

Note that this format differs from that in previous versions of the catalog. The last 3 columns give information on the epoch of observation for each source and are described below in the observation epoch section. Two other changes were new in the previous release. The P(S) column, which indicates the probability that the source is a sidelobe, replaces the previous binary sidelobe flag column. The columns following the field name give information on counterparts to the FIRST source in the SDSS DR9 catalog and the 2MASS catalog. These parameters are described in detail below in the description of the P(S) column and the counterparts columns.


The catalog history page describes previously released versions of the FIRST catalogs, which are still available for historical purposes. We recommend that the new catalog be used where possible for all projects.