COSMOS VLA Deep Catalog Definitions

COSMOS Overview

The COSMOS Archive serves data taken for the Cosmic Evolution Survey (COSMOS) project. COSMOS is an astronomical survey designed to probe the formation and evolution of galaxies as a function of cosmic time (redshift) and large scale structural environment. The survey covers a 2 square degree equatorial field with imaging by most of the major space-based telescopes (Hubble, Spitzer, GALEX, XMM, Chandra) and a number of large ground based telescopes (Subaru, VLA, ESO-VLT, UKIRT, NOAO, CFHT, and others).

IRSA serves the COSMOS archive using the following search methods:

• Spatial search on all images and small catalogs, using Atlas
• Advanced search on only the larger catalogs, using Gator

COSMOS VLA Deep Catalog

These VLA data represent the additional 62 hrs of 1.4 GHz (20cm) observations of the central 7 pointings already imaged by the large project in A-configuration in February/March 2006. The observations have been combined with the large project in which the 2 square degree COSMOS field with the position given above as the center of the field was surveyed for 275 hours. The observations of the large project were performed at 1.4 GHz (20 cm), using the VLA in its A- and C-configuration between September 2004 and September 2005. The final combined survey has reached a sensitivity of an rms of uJy/beam in the central 30' at a resolution of 2.5"x2.5".

The key characteristics of these data:

• Configuration: VLA A-array & C-array
• Dates of observations:
  • September, 2004 - January, 2005 (A-array)
  • August, 2005 - September, 2005 (C-array)
  • February/March, 2006 (A-array: central 7 pointings)
• Observing time:
  • 250 hours (A-array)
  • 25 hours (C-array)
  • 62 hours (A-array: central 7 pointings)
• Frequency: 1.4 GHz ( = L band, 20cm)
• Bandwidth: 75 MHz (Multi-channel continuum mode)
• Pointings: 23 (hexagonal pattern)
• Area: 2 sq degs (box used for source extraction)
• Resolution: 2.5" x 2.5"
• Sensitivity: 10-40 uJy/beam (inner to outermost regions)

Further information may be obtained from the VLA-COSMOS web page: http://www.mpia-hd.mpg.de/COSMOS or the main COSMOS web page: http://cosmos.astro.caltech.edu/.

The data reduction, image reconstruction, catalog construction and bandwidth correction is similar to the procedures for the large project described in:

"The VLA-COSMOS Survey: II. Source Catalog of the Large Project" by Schinnerer et al. 2007, ApJS, COSMOS special issue, 172, 46

"The VLA-COSMOS Survey: III. Further Catalog Analysis and the Radio Source Counts" by Bondi et al., 2008, ApJ, 681, 1129

More details will be presented by Schinnerer et al. (in prep.) "The VLA-COSMOS Survey: IV. Joint Source Catalog of the Large and Deep Project"

COSMOS VLA Deep Catalog Column Definitions

Gator serves the COSMOS May 2010 VLA Deep Source Catalog (25 columns [20 delivered + 5 IRSA-created], 2,865 data rows). The column descriptions can be found below.

Column Name	Data Type	Units	Description
dp_name	char		Source name
lp_name	char		Source name in VLA-COSMOS Large project catalog
ra	float	degree	RA (J2000), degrees
dec	float	degree	Declination (J2000), degrees
cra	char	hh_mm_ss.sss	RA (J2000), HMS
cdec	char	ddd_mm_ss.ss	Declination (J2000), DMS
er_ra	float	arcsec	rms uncertainty on source position RA
er_dec	float	arcsec	rms uncertainty on source position Declination
fp	float	mJy	1.4 GHz peak surface brightness of source
fp_corr	float	mJy	peak surface brightness corrected for bandwidth smearing
fperr	float	mJy	rms uncertainty on peak flux
flux	float	mJy	integrated source flux density
ferr	float	mJy	rms uncertainty on integrated source flux
rms_bg	float	mJy	measured rms at the radio source position
bmaj	float	arcsec	deconvolved source size - major axis (0.00 - unresolved)
bmin	float	arcsec	deconvolved source size - minor axis
pa	float	degree	position angle
res	int		flag for resolved source: -2 unresolved only in VLA-COSMOS Deep image -1 resolved only in VLA-COSMOS Large image 0 unresolved in both VLA-COSMOS Large & Deep images 1 resolved in both VLA-COSMOS Large & Deep images 2 resolved only in VLA-Deep image
mult	int		flag for multi-component source: 0 no multi-component source 1 source identified in VLA-COSMOS Large image 2 source identified in VLA-COSMOS Deep image
memb	int		flag for catalog membership: -1 only detected in the VLA-COSMOS Large image 0 detected in both the VLA-COSMOS Large & Deep image 1 only detected in the VLA-COSMOS Deep image
det	int		flag specifying resolution of source detection: -1 S/N>=5 is only satisfied at a resolution of 1.5" 0 S/N>=5 is only satisfied at both 1.5" and 2.5" resolution 1 S/N>=5 is only satisfied at a resolution of 2.5", but in both the large and small scale (105" and 17.5" box size, respectively) rms map 2 S/N>=5 is only satisfied at a resolution of 2.5", only in the small scale (17.5" box size) rms map