The FIRST Survey Catalog: 14Dec17 Version

A catalog for the north and south Galactic caps (946,432 sources), derived from the 1993 through 2011 observations, is available as a gzip-compressed ASCII file (catalog_14dec17.bin.gz) and as a FITS binary table (first_14dec17.fits.gz). The file size is 41 MBytes compressed (156 MBytes uncompressed) for the ASCII version and 66 MBytes compressed (113 MBytes uncompressed) for the FITS version. The catalog covers a total of about 10,575 square degrees of sky (8,444 square degrees in the north Galactic cap and 2,131 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.

This catalog is identical to the previous version (14Mar04) except that it has more accurate data on which sources are not covered by the SDSS DR10 catalog. Approximately 1000 sources that were indicated as covered by DR10 in the previous version are now correctly marked as not covered. The source list, radio fluxes, etc., are all the same as the last version.

NOTE: In this version of the catalog, images taken in the the new EVLA configuration have been re-reduced using shallower CLEAN thresholds in order to reduce the "CLEAN bias" in those images. Also, the EVLA images are not co-added with older VLA images to avoid problems resulting from the different frequencies and noise properties of the configurations. That leads to small gaps in the sky coverage at boundaries between the EVLA and VLA regions. As a result, the area covered by this release of the catalog is about 60 square degrees smaller than the earlier release of the catalog (13Jun05), and the total number of sources is reduced by nearly 25,000. The previous version of the catalog does have sources in the overlap regions, but their flux densities are considered unreliable due to calibration errors. The flux densities should be more accurate in this catalog, biases are smaller, and the incidence of spurious sources is also reduced.

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.

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

The format of this catalog is the same as releases since 13Jun05 but differs from earlier 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. 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 DR10 catalog and the 2MASS catalog. These parameters are described in detail below in the description of the P(S) column and the counterparts columns. Other catalog columns are common with FIRST catalog releases extending back over the past decade.


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.