The FIRST Survey Catalog

This is the description of the 1999 July 21 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 It has been replaced by a newer catalog.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 (549,707 sources), derived from the 1993 through 1998 observations, is currently available as a gzip-compressed ASCII file (catalog_99jul21.bin.gz). The file size is 17.8 Mbytes compressed (59.4 Mbytes uncompressed). The catalog covers about a total of 6060 square degrees of sky (5450 square degrees in the north Galactic cap and 610 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. The northern strip at Dec=0 was observed this year because that is the sky area currently being observed by the SDSS.

No new data were taken for the south Galactic cap during the past observing season, but the southern images south of about -2 degrees were reprocessed with an improved pipeline script that substantially reduces the sidelobe levels in a small fraction of the fields. Consequently, many of the southern sources have slight changes in their positions, flux densities, and other properties; a small number of sources from the previous catalog are missing from this 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 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,
1999 July 21