What's New in FIRST?

2014 December 17

A new catalog is now online. The 14Dec17 version of the catalog includes all the data collected for the FIRST survey. There are 946,432 sources in the catalog and the sky area covered is a total of 10,575 square degrees (8444 square degrees in the north, 2131 square degrees in the south).

This catalog is identical to the previous 14Mar04 release except that it includes more accurate information on which FIRST sources are not covered by the SDSS DR10 survey. 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.

For this version of the catalog, many south Galactic cap images taken in 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 previous release of the catalog, 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.

The catalog format is the same as the previous version. It includes information on the epoch of observation for each source and on counterparts from SDSS DR10 and 2MASS. See the catalog description for more information.

This is probably a nearly final version of the FIRST catalog. The only known issues are the gaps in sky coverage mentioned above (which might never get fixed). This version of the catalog should be reliable for most purposes, and the vast majority of the sources are not expected to change.

The images that were used to construct this catalog are available through the FIRST Image Cutout Server. The new images have names that end with W or X; the "W" images include only data from the new EVLA configuration (which has different frequencies and noise properties). The "X" images are around the edges of the EVLA region and include only the older pre-EVLA observations.

2014 March 4

A new catalog is now online. The 14Mar04 version of the catalog includes all the data collected for the FIRST survey. There are 946,432 sources in the catalog and the sky area covered is a total of 10,575 square degrees (8444 square degrees in the north, 2131 square degrees in the south).

For this version of the catalog, many south Galactic cap images taken in 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 previous release of the catalog, 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.

The catalog format is the same as the previous version. It includes information on the epoch of observation for each source and on counterparts from SDSS DR10 and 2MASS. See the catalog description for more information.

This is probably a nearly final version of the FIRST catalog. The only known issues are the gaps in sky coverage mentioned above (which might never get fixed), and a problem with the sky coverage for the SDSS DR10 catalog. Note that the sky coverage issue is fixed in the 14Dec17 version of the catalog.

The images that were used to construct this catalog are available through the FIRST Image Cutout Server. The new images have names that end with W or X; the "W" images include only data from the new EVLA configuration (which has different frequencies and noise properties). The "X" images are around the edges of the EVLA region and include only the older pre-EVLA observations.

2013 June 5

A new catalog is now online. Many images, particularly in the south Galactic cap, were remade to improve the signal-to-noise and reduce sidelobes. The 13Jun05 version of the catalog includes all the data collected for the FIRST survey. There are 971,268 sources in the catalog and the sky area covered is a total of 10,635 square degrees (8444 square degrees in the north, 2191 square degrees in the south).

This version of the catalog has a modified format compared with the previous version. New fields were added to the catalog giving the epoch of observation for each source. It includes information on counterparts from SDSS DR9 and 2MASS. As in the previous version, the catalog includes a sidelobe probability, which indicates whether a source is likely to be spurious or not. See the catalog description for more information.

This version of the data includes observations made using a new configuration enabled by the EVLA upgrades. The frequency bandwidth is wider and the central frequencies of the bands have changed. See the observation status page for more details.

This is probably a nearly final version of the FIRST catalog. The only known issues are a small calibration error in regions observed with the EVLA configuration, and a problem with the sky coverage for the SDSS DR9 catalog. A new catalog fixing these minor problems is expected to be released soon; that is likely to be the final FIRST catalog release. The vast majority of the sources are not expected to change.

2012 November 9

The third.ucllnl.org web server has been restored to service. We have redirected image access to the number server at http://third.ucllnl.org. Note that the backup server at http://first.astro.columbia.edu remains available, but since the image collection on that server is slightly out-of-date compared with third.ucllnl.org, we recommend the use of third.ucllnl.org for most purposes.

2012 October 10

As a result of a major computer crash on the third.ucllnl.org web server, we have temporarily redirected image access to a backup image server at http://first.astro.columbia.edu. The image collection on that server is slightly out-of-date compared with third.ucllnl.org, but most images should be available. We will restore the service on third.ucllnl.org as soon as possible.

Scripts that go directly to third.ucllnl.org will need to be modified to access first.astro.columbia.edu instead.

2012 February 24

Both a new catalog and new images are now online. New data were acquired in the southern Galactic cap in spring 2011. Some older images were also remade to improve their quality and remove bad data. The 12Feb16 version of the catalog includes all the data collected through spring 2011. With the addition of the new data, there are 946,464 sources in the catalog and the sky area covered is a total of 10,635 square degrees (8444 square degrees in the north, 2191 square degrees in the south). The southern catalog area is more than 3.5 times larger than the previous catalog.

This version of the catalog has a slightly modified format compared with the previous version. It includes information on counterparts from SDSS and 2MASS, but does not include information from the GSC2 catalog. As in the previous version, the sidelobe flag has been replaced by a sidelobe probability, which gives a considerably more accurate assessment of whether a source is likely to be spurious or not. See the catalog description for more information.

This version of the data includes observations made using a new configuration enabled by the EVLA upgrades. The frequency bandwidth is wider and the central frequencies of the bands have changed. See the observation status page for more details.

2010 May 12

Additional images in the southern Galactic cap are now online. The data were acquired in spring 2009. There are currently some sidelobe issues in the data related to a severe interference environment and the hybrid VLA/EVLA receivers that were in use at the time. We are continuing to work on improving the images, but they should already be useful for many projects.

The new area covers a total of 1466 square degrees in the south, an increase by a factor of 2.4 compared with the previous release. The total FIRST sky area is now 9909 square degrees. We plan to extend the southern area further during the next EVLA B-configuration so that the entire SDSS-3 sky survey area is covered.

There is not as yet a released catalog for this new area due to the sidelobe problems mentioned above; we expect to have a catalog available sometime this fall.

2008 October 31

Two format errors has been corrected in the 08jul16 catalog. Some SDSS catalog matches had magnitudes of -9999, which caused a format overflow. Those magnitudes are now shown as -1 in our catalog. The deconvolved major and minor axes for sources with fitted sizes smaller than the beam are now given as zero instead negative values (which is consistent with previous FIRST catalogs).

The new catalog is available at the same location as the previous erroneous version. There is now a FITS binary table version of the catalog available in addition to the ASCII version.

2008 July 21

A new catalog has been released that includes all data taken through 2004. This catalog covers about 8444 square degrees in the north Galactic cap and 611 square degrees in the south Galactic cap, for a total of 9055 square degrees containing ~816,000 sources. The new catalog and images are accessible via the FIRST Search Engine and the FIRST Cutout Server.

This catalog includes a small amount of new data from observations that filled in various small holes in the last release and that replaced some bad fields. It also uses combined images from two epochs of observation in the southern Galactic cap equatorial stripe to produce a deeper catalog in that area, with a typical flux density detection threshold of 0.75 mJy.

This version of the catalog has a modified format. The sidelobe flag has been replaced by a new sidelobe probability, which gives a considerably more accurate assessment of whether a source is likely to be spurious or not. There are various other changes as well, including information on counterparts from the SDSS, 2MASS and GSC2 catalogs. See the catalog description for more information.

We have also updated the FIRST web pages.

2004 August 23

The FIRST image archive at the Space Telescope Science Institute is now fully up-to-date with the current catalog and the cutout server. Access to the full-sized FIRST images is now quite easy and no longer requires a Hubble archive account. The data can be retrieved either through a search interface or through anonymous ftp.

2003 April 11

A new catalog has been released that includes all data taken through September 2002. This catalog covers about 8422 square degrees in the north Galactic cap and 611 square degrees in the south Galactic cap, for a total of 9033 square degrees containing ~811,000 sources. The new catalog and images are accessible via the FIRST Search Engine and the FIRST Cutout Server.

The FIRST survey is now substantially complete. We plan to release additional catalogs, including a version with improved sidelobe flagging and deeper observations of the southern equatorial strip (with variability information). We may also acquire a small amount of additional data to fill holes within the surveyed area. We are not likely to expand significantly the area now covered, however.

We hope you have enjoyed the show.

2001 November 8

All the images from the FIRST survey data taken to date (through May 2001) are now available on the FIRST Cutout Server.

2001 October 18

A paper describing optical counterparts to FIRST radio sources from the APM POSS-I catalog is now available. This is the third major paper on which much of the FIRST survey science is based. Optical identifications are obtained for more than 70,000 radio sources; approximately 19% of the cataloged FIRST sources have counterparts. Both the paper and the data are available online.

2001 October 15

A new catalog has been released that includes all data taken through May 2001. This catalog covers about 7954 square degrees in the north Galactic cap and 611 square degrees in the south Galactic cap, for a total of 8565 square degrees containing ~771,000 sources. The new catalog and images are accessible via the FIRST Search Engine. The most recent images are not yet available through the FIRST Cutout Server, but they should be loaded on the server shortly.

2001 September 26

The FIRST image cutout server has been restored to its normal address. Its URL is the same as before:
http://third.ucllnl.org/cgi-bin/firstcutout

Please let us know of any problems.

2001 September 25

Due to new security measures at LLNL, the FIRST image cutout server has had its web address changed to http://third.ucllnl.org:8080/cgi-bin/firstcutout. If you have bookmarks to the old address they will not work. Instead, follow the link from the FIRST home page (or the link given above) to get the new address. We hope that this change is only temporary. We apologize for the inconvenience and for the inaccessibility of the cutout server for the past few days.

2000 December 1

The FIRST catalog search and image cutout pages have been improved. The image cutout extraction has been speeded up substantially. The RA/Dec entry boxes on the web forms have been combined into a single entry box, which will make pasting text from other windows into the form more convenient. Additional help information is also now available.

Note that the interfaces to the CGI scripts have not been modified, so existing scripts that access the catalog and image servers directly will continue to work without modification.

2000 September 25

The FIRST publications page has been completely overhauled and now includes a much more complete list of papers from the FIRST team.

2000 August 28

The composite quasar spectra derived by Brotherton et al. (2000) from the FIRST Bright Quasar Survey (White et al. 2000) are available. See the FIRST publications page for more information.

2000 August 21

The FIRST web pages now have a search engine courtesy of Google.

2000 July 17

A new catalog has been released that includes all data taken through February 2000. This catalog covers about 7377 square degrees in the north Galactic cap and 611 square degrees in the south Galactic cap, for a total of nearly 8000 square degrees containing ~722,000 sources. The new catalog and images are accessible via the FIRST Search Engine and the FIRST Cutout Server.

2000 March 2

The FIRST image cutout server web address has changed as a result of a reorganization of the computers at IGPP/LLNL. The new URL is http://third.ucllnl.org/cgi-bin/firstcutout.

1999 July 21

A new catalog has been released that includes all data taken through the end of 1998. This catalog covers about 5450 square degrees in the north Galactic cap and 610 square degrees in the south Galactic cap, for a total of more than 6000 square degrees containing ~550,000 sources. The new catalog and images are accessible via the FIRST Search Engine and the FIRST Cutout Server.

1998 April 8

FIRST Survey renewed! We have just been informed by NRAO that the FIRST survey continuation proposal has been accepted and that FIRST will be scheduled for 450 hours of observing this summer and 600 hours in the fall 1999 VLA B-configuration.

1998 February 4

Two new catalogs covering both the north and south Galactic caps have been released. These catalogs now include nearly 5000 square degrees of sky covering most of the area

• North: 7^h20^m < RA(2000) < 17^h20^m, 22.2° < Dec < 57.5°
• Equatorial Strip: 21^h20^m < RA(2000) < 3^h20^m, -2.5° < Dec < 1.6°
• Southern Strip: An odd-shaped strip at about -10° with roughly the same RA limits as the equatorial strip was also observed. This strip was defined by the SDSS project; see the coverage map for details.

Combined, the northern and southern catalogs contain ~437,000 sources.

The new catalog is also accessible via the FIRST Search Engine.

1997 August 14

The FIRST acronym has been registered with the International Astronomical Union. The full IAU naming convention should be used to designate FIRST sources in publications.

1997 April 24

Two new catalogs, covering both the north and south Galactic caps have been released! These catalogs now include nearly 3000 square degrees of sky covering most of the area

• North: 7^h20^m < RA(2000) < 17^h20^m, 22.2° < Dec < 42.5°
• South: 21^h20^m < RA(2000) < 3^h20^m, -2.5° < Dec < 1.6°

Combined, the northern and southern catalogs contain ~268,000 sources.

By popular demand the catalog is in a new, easier-to-use format that gives both the fitted and deconvolved source sizes. The major and minor axes are also given with greater precision (to 0.01 arcsec), which will make it simpler to do analysis based on these quantities.

The new catalog is also accessible via the FIRST Search Engine.

1997 March 6

A paper describing the discovery of two FIRST radio-selected broad absorption line QSOs, one of which is the first radio-loud BAL QSO ever found, has been accepted for publication in the Astrophysical Journal (Letters).

1997 February 27

A new catalog of the north Galactic cap has been released! This third catalog includes about 2575 square degrees of sky covering most of the area 7^h20^m < RA(2000) < 17^h20^m, 22.2° < Dec < 42.5°. It contains ~236,000 sources.

The new catalog is also accessible via the FIRST Search Engine.

1997 February 3

All of the FIRST images taken to date, including those north of declination +35°, are now online in the FIRST Image Cutout Server.

1997 January 23

The FIRST Image Cutout Server is now available. Enter a position in the FIRST survey area and the server returns a section of a FIRST image. The returned image can be a labeled GIF image (displayed within your Web browser), a FITS file, or a FITS image (displayed in a helper applications.)

The cutout server is also linked to the FIRST Search Engine, so you can obtain radio images of objects located in your catalog searches. See the help page for more information.

1996 December 20

Revised versions of the HTML and Postscript versions of the Cress et al. paper on the two-point angular correlation of the FIRST catalog are now available.

1996 October 9

The FIRST Search Engine is now on-line. This Web page allows you to search the catalog both by position and using other catalog parameters (e.g. fluxes and sizes.) The results are linked to the NASA/IPAC Extragalactic Database (NED) and the STScI Digitized Sky Survey, making it easy to get optical finding charts and to find identifications from the literature. Try it and let us know how you like it and what additional features you would like to see.

1996 October 2

More than 5000 images from the FIRST survey are now available through the HST data archive. Note that the HST archive now has a Web interface, making use of the archive as a source for these images simpler than in the past.

1996 August 26

The catalog paper has been revised in light of comments from the referee and has now been accepted by the Astrophysical Journal. Both the HTML and Postscript versions have been updated. Users of the catalog should read this paper, which is now in final form.

1996 July 15

Cress et al. have obtained the first high-significance two-point angular correlation for a deep radio sample through an analysis of the FIRST catalog.

1996 May 28

A new catalog has been released. The 96May28 catalog is almost identical to the previous version, but an error has been corrected in the position angles of some elliptical sources that are unresolved in one direction. The previous version of the catalog is still available; see the new catalog history for information on all previously released versions of the FIRST catalog.

1996 May 7

A paper has been submitted to the Astrophysical Journal describing the construction of the FIRST catalog. Users of the catalog should read this paper.

A paper describing spectroscopic followup observations of bright quasar candidates in the FIRST catalog has been accepted for publication in the August 1996 Astronomical Journal.

A coverage map is available giving the rms noise as a function of position in the FIRST survey area. This map can be used to determine upper limits for objects not detected in the survey area.

1995 October 16

A new catalog has been released! This second catalog includes about 1550 square degrees of sky covering most of the area 7^h45^m < RA(2000) < 17^h30^m, 28.4° < Dec < 42°. It contains ~138,000 sources.

Our WWW pages have undergone some modest changes to make them easier to navigate. We've also added some some formatting niceties that you'll appreciate if you use Netscape as a Web browser.

1995 October 10

Our 1995 observing run at the VLA began on October 10. We will be observing about 10,000 more fields between now and the end of 1995; the total survey area covered at that time will be about 3000 square degrees. As before, the data products (images and catalogs) will be made publicly available after their quality has been verified. Watch for initial data releases in the fall of 1996.