The FIRST Survey Catalog: 12Feb16 Version

A catalog for the north and south Galactic caps (946,464 sources), derived from the 1993 through 2011 observations, is available as a gzip-compressed ASCII file (catalog_12feb16.bin.gz) and as a FITS binary table (first_12feb16.fits.gz). The file size is 36 MBytes compressed (130 MBytes uncompressed) for the ASCII version and 46 MBytes compressed (80 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.

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 all previous versions of the catalog.

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----
   RA           Dec        P(S)    Fpeak      Fint    RMS     Maj    Min   PA    fMaj   fMin   fPA Field         #  Sep    i  Cl  #  Sep    K  
14 35 55.835 +64 34 04.69 0.014     1.75      1.83   0.158   1.95   0.00  14.9   5.74   5.29  14.9 14360+64240M  0 99.00 99.00 -  0 99.00 99.00
11 27 20.244 +64 32 34.60 0.576     1.03      0.70   0.143   0.00   0.00 113.3   4.86   4.10 113.3 11300+64240M  1  5.32 18.44 s  1  5.27 15.47
06 57 23.618 +64 32 33.37 0.014     1.21      1.75   0.137   5.80   0.00 147.5   7.93   5.33 147.5 07000+64243J  1  6.90 21.53 g  0 99.00 99.00
13 21 43.254 +64 32 30.72 0.289     1.16      4.31   0.147  10.96   7.04  21.5  12.22   8.88  21.5 13240+64240M  0 99.00 99.00 -  0 99.00 99.00
10 07 16.439 +64 32 30.69 0.014     1.35      0.99   0.148   1.58   0.00   7.6   5.62   3.79   7.6 10060+64240M  1  1.56 20.69 s  0 99.00 99.00

Note that this format differs from that in previous versions of the catalog. 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 DR8 catalog and the 2MASS catalog. These new 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.