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PIGSSELCNF - Allen Telescope Array Pi GHz Sky Survey (PiGSS) Deep Fields Source Catalog

HEASARC
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Overview

This table contains results from a total of 459 repeated 3.1-GHz radio continuum observations (of which 379 were used in a search for transient sources) of the ELAIS-N1, Coma, Lockman Hole, and NOAO Deep Wide Field Survey (NDWFS) fields as part of the Allen Telescope Array (ATA) Pi GHz Sky Survey (PiGSS). The observations were taken in 2 simultaneous 100-MHz wide bands centered at 3.04 and 3.14 GHz approximately once per day between 2009 May and 2011 April. Each image covers 11.8 square degrees and has 100" FWHM resolution. Deep images for each of the four fields have rms noise between 180 and 310 microJy (uJy), and the corresponding catalogs contain ~200 sources in each field. Typically 40-50 of these sources are detected in each single-epoch image. This represents one of the shortest cadence, largest area, multi-epoch surveys undertaken at these frequencies. The authors compared the catalogs generated from the combined images to those from individual epochs, and from monthly averages, as well as to legacy surveys. They undertook a search for transients, with particular emphasis on excluding false positive sources,but find no confirmed transients, defined here as sources that can be shown to have varied by at least a factor of 10. However, the authors found one source that brightened in a single-epoch image to at least six times the upper limit from the corresponding deep image. They also found a source associated with a z = 0.6 quasar which appears to have brightened by a factor ~3 in one of their deep images, when compared to catalogs from legacy surveys. The authors place new upper limits on the number of transients brighter than 10 mJy: fewer than 0.08 transients deg-2 with characteristic timescales of months to years; fewer than 0.02 deg-2 with timescales of months; and fewer than 0.009 deg-2 with timescales of days.

In this study, the authors accepted only as real sources those that are independently detected in both frequencies in at least one epoch (with a position matching tolerance of 50", corresponding to a false match probability of <2%). Their threshold of ~ 4.2 sigma for detection in a single image corresponds to a threshold of ~ 5.9 sigma in the dual-image catalog. They generated catalogs for the deep fields, consisting only of sources detected at both frequencies, and these are contained in the present HEASARC table.

Notice that the authors previously published a list of 425 radio sources in the NDWFS field in the constellation of Bootes in an earlier paper (Bower et al 2010, ApJ, 725, 1792, available as the HEASARC database table PIGSSBOOFD). In the 2013 paper, they have performed a partial re-analysis of these data to conform with the updated analysis techniques used on the other three fields.


Catalog Bibcode

2013ApJ...762...93C

References

The Allen Telescope Array Pi GHz Sky Survey. III. The ELAIS-N1, Coma, and
Lockman Hole Fields.

     Croft S., Bower G.C., Whysong D.
    <Astrophysical J, Volume 762, Issue 2, article id. 93, 25 pp. (2013)>.
    =2013ApJ...762...93C

Provenance

This table was created by the HEASARC in March 2013 based on electronic versions of Tables 2, 3, 4 and 5 (source lists for each of the 4 fields, ELAIS N1, Lockman, Coma, and NDWFS, respectively) from the reference paper which were obtained from the ApJ web site. The HEASARC has created a new parameter called field_name which identifies in which table/field the source can be found. Thus, to select only sources in the Lockman Hole field, the user should select field_name= 'Lockman'.

Parameters

Name
The PiGSS source designation using the survey acronym and the J2000.0 equatorial coordinates of the source rounded to the nearest second of time in RA and arcsecond in Declination, e.g., 'PiGSS J125411+273734'. In the machine-readable ApJ tables from which this HEASARC table was constructed these names were rendered with a 'p' rather than a '+' sign. #

Field_Name
This table was created by the HEASARC in March 2013 based on electronic versions of Tables 2, 3, 4 and 5 (source lists for each of the 4 fields, ELAIS N1, Lockman, Coma, and NDWFS, respectively) from the reference paper which were obtained from the ApJ web site. This parameter identifies in which table/field the source can be found, as follows:

  Field_name    Table Number  Num. of Sources
  ELAIS N1           2            238
  Lockman            3            189
  Coma               4            186
  NDWFS              5            195
  

RA
The Right Ascension of the PiGSS radio source in the selected equinox. This was given in J2000.0 decimal hours to a precision of 10-5 hours (0.036 seconds of time) in the original table.

Dec
The Declination of the PiGSS radio source in the selected equinox. This was given in J2000.0 decimal degrees to a precision of 10-5 degrees (0.036 arcseconds) in the original table.

LII
The Galactic Longitude of the PiGSS radio source.

BII
The Galactic Latitude of the PiGSS radio source.

Major_Axis
The measured major axis of the PiGSS radio source, assumed to be an elliptical Gaussian with a minimum size of the synthesized ATA beam (100 arcseconds), in arcseconds.

Minor_Axis
The measured minor axis of the PiGSS radio source, assumed to be an elliptical Gaussian with a minimum size of the synthesized ATA beam (100 arcseconds), in arcseconds.

Position_Angle
The measured position angle of the major axis of the PiGSS radio source, assumed to be an elliptical Gaussian with a minimum size of the synthesized beam (100 arcseconds), in degrees.

Flux_3p04_GHz
The 3.04-GHz flux density of the PiGSS radio source, as measured from the deep image of the field in which it lies and made from all good data, in mJy.

Flux_3p04_GHz_Error
The uncertainty in the deep image 3.04-GHz flux density of the PiGSS radio source, in mJy. Quoted uncertainties are the sum in quadrature of the uncertainties on the fit and on the background measurement as reported by SFIND.

Flux_3p14_GHz
The 3.14-GHz flux density of the PiGSS radio source, as measured from the deep image of the field in which it lies and made from all good data, in mJy.

Flux_3p14_GHz_Error
The uncertainty in the deep image 3.14-GHz flux density of the PiGSS radio source, in mJy. Quoted uncertainties are the sum in quadrature of the uncertainties on the fit and on the background measurement as reported by SFIND.

Num_3p04_GHz_Images
The number of single-epoch images with completeness better than 50 mJy in which this source was detected, at the frequency of 3.04 GHz.

Num_3p14_GHz_Images
The number of single-epoch images with completeness better than 50 mJy in which this source was detected, at the frequency of 3.14 GHz.

Num_Both_Freq_Images
The number of well-behaved epochs (post-imaging calibration gain within +/- 0.1 of the median value; see Section 3.4 of the reference paper) with completeness better than 50 mJy in which the source was simultaneously detected in each of the single-frequency images.

Reduced_Chi2_3p04_GHz
The reduced chi-squared of the source at 3.04 GHz for the hypothesis of no variability, computed using only well-behaved epochs where the source is detected at both frequencies in five or more epochs.

Reduced_Chi2_3p14_GHz
The reduced chi-squared of the source at 3.14 GHz for the hypothesis of no variability, computed using only well-behaved epochs where the source is detected at both frequencies in five or more epochs.

Sigma_To_Mean_3p04_GHz
The ratio of the standard deviation over the mean of the single-epoch flux density for the source at 3.04 GHz, computed using only well-behaved epochs where the source is detected at both frequencies in five or more epochs.

Sigma_To_Mean_3p14_GHz
The ratio of the standard deviation over the mean of the single-epoch flux density for the source at 3.14 GHz, computed using only well-behaved epochs where the source is detected at both frequencies in five or more epochs.


Contact Person

Questions regarding the PIGSSELCNF database table can be addressed to the HEASARC User Hotline.

Page Author: Browse Software Development Team
Last Modified: 14-Mar-2013