The FIRST Survey Catalog: 01Oct15 Version

This is the description of the 2001 October 15 FIRST catalog. It has been replaced by a newer catalog. Old released versions of the FIRST catalog are made available for archival purposes for the benefit of those who have already started research programs based on those catalogs. The newest version is always preferred for new projects.

See the catalog history for information on changes in the various FIRST catalogs.

A catalog for the north and south Galactic caps (771,076 sources), derived from the 1993 through 2001 observations, is currently available as a gzip-compressed ASCII file (catalog_01oct15.bin.gz). The file size is 25.2 Mbytes compressed (83.3 Mbytes uncompressed). The catalog covers a total of about 8565 square degrees of sky (7954 square degrees in the north Galactic cap and 611 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 concide the area planned to be covered by the Sloan Digital Sky Survey. No new data were taken for the south Galactic cap during the past observing season, so the current catalog is practically identical to the previous catalog in the south.

For this version of the catalog, most of the maps constructed from the previous round of observations (in 1999) were remade to correct a small error in the annual aberration correction (due to a Y2K error in the observation date string.) This led to numerous small changes in the positions and flux densities for sources in the area covered by the 1999 observations. The differences are generally much smaller than the uncertainties: the mean position shift is 0.032 arcsec and the mean flux change is 0.015 mJy, though in rare cases they can be larger.

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 right ascension and has the following format:

    RA  (2000)   Dec      W    Fpeak      Fint    Rms     Maj    Min    PA   fMaj   fMin   fPA Field Name
06 50 44.043 +31 10 00.09       1.16      0.64   0.147   0.00   0.00  42.0   4.50   3.59  42.0 06510+31143E
06 51 02.181 +31 11 13.33       1.58      2.66   0.139   4.99   3.94  91.6   7.35   6.69  91.6 06510+31143E
06 51 03.826 +31 13 03.32 W     1.02      1.42   0.137   7.63   0.00   2.4   9.35   4.34   2.4 06510+31143E
06 51 06.134 +31 19 02.00       7.29      9.64   0.145   4.09   1.82 131.3   6.77   5.70 131.3 06510+31143E
06 51 10.784 +31 11 28.80      72.36    100.79   0.141   4.18   2.49   9.8   6.83   5.95   9.8 06510+31143E
Note that this format is the same as the most recent versions of the catalog but has changed from the oldest versions.

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.

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Richard L. White,
2001 Oct 15