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VLAGOODSN - VLA GOODS-North Field 1.4-GHz Source Catalog

HEASARC
Archive

Overview

This table contains results from deep, new, wide-field radio continuum observations of the Great Observatories Origins Deep Survey-North (GOODS-North) field. (The GOODS-North field covers ~160 arcmin2 centered on the Hubble Deep Field North (Williams et al. 1996, AJ, 112, 1335) and is unrivaled in terms of its ancillary data sets, which include extremely deep Chandra, Hubble Space Telescope (HST), and Spitzer observations, deep UBVRIJHK ground-based imaging and ~3500 spectroscopic redshifts from 8 to 10 m telescopes). The resulting 1.4-GHz map has a synthesized beam size of ~1.7" and an rms noise level of ~3.9 microJansky per beam (uJy/beam) near its center and ~8 uJy/beam at 15 arcminutes from phase center. The authors have cataloged 1230 discrete radio emitters, within a 40' x 40' region, above a 5-sigma detection threshold of ~20 uJy at the field center. New techniques, pioneered by Owen & Morrison (2008, AJ, 136, 1889), have enabled the authors to achieve a dynamic range of 6800:1 in a field that has significantly strong confusing sources. The authors compare the 1.4-GHz (20-cm) source counts with those from other published radio surveys. Their differential counts are nearly Euclidean below 100 uJy with a median source diameter of ~1.2". This adds to the evidence presented by Owen & Morrison that the natural confusion limit may lie near 1 uJy. If the Euclidean slope of the counts continues down to the natural confusion limit as an extrapolation of their log N-log S, this indicates that the cutoff must be fairly sharp below 1 uJy, else the cosmic microwave background temperature would increase above 2.7K at 1.4GHz.

A useful combined total of 165 hours of NRAOS's Very Large Array (VLA) A-configuration 1.4-GHz observations were obtained between 2005 February and 2006 February, all done at night so as to avoid solar interference, for a region centered at RA and Dec of 12:36:49.4, +62:12:58 (J2000). (See Table 1 of the reference paper for the VLA observing log)


Catalog Bibcode

2010ApJS..188..178M

References

Very Large Array 1.4 GHz observations of the GOODS-North field: data reduction
and analysis.
    Morrison G.E., Owen F.N., Dickinson M., Ivison R.J., Ibar E.
   <Astrophys. J. Suppl. Ser., 188, 178-186 (2010)>
   =2010ApJS..188..178M

Provenance

This table was created by the HEASARC in September 2013 based on CDS Catalog J/ApJS/188/178 file table2.dat

HEASARC Implementation

The HEASARC has made a number of revisions to the version of this catalog that was supplied to the CDS.

(1) It has created a new source_number parameter that uniquely specifies each source after discovering that the original source numbers in the catalog were not unique. For the sake of completeness these latter have been retained herein (the parameter called original_source_number).

(2) The original source number values encoded the origin of the sources: values below 10,000 related to those sources found by the AIPS SAD algorithm while those above 10,000 were the sources found and investigated "by hand" of the authors. To make this distinction more explicit, the HEASARC has added a new parameter called source_type which has been set to 'S' for the former SAD-detected sources and to 'H' for the latter hand-selected sources.

(3) The HEASARC has converted the units of the flux densities and their errors in this table from the units of microJanskys per beam (uJy/beam) for peak flux densities and uJy for integrated flux densities to milliJansky per beam (mJy/beam) and mJy, respectively.

(4) After consultation with the first author, the HEASARC has also revised the naming convention for these GOODS-North VLA sources to a position-based one (rather than the source number-based one recommended by the Dictionary of Nomenclature of Celestial Objects), using the prefix of 'GOODS VLA' and the J2000.0 equatorial coordinates of the source.


Parameters

Source_Number
A uniquely identifying source number for each detected 1.4-GHz source in the catalog in order of increasing J2000.0 Right Ascension. The HEASARC created this parameter after discovering that the original source numbers in the catalog were not unique.

Orig_Source_Number
The original source number in the CDS version of this catalog. In 81 cases, these source numbers were not unique: in 78 cases, 2 sources at different positions had the same (original) source number, in 2 cases, 3 sources at different positions had the same (original) source number, and, in 1 case, 4 sources shared the same (original) source number. In this last case, which corresponded to 4 entries with original_source_number = 2, 2 of the 4 entries were at exactly the same position, and had identical values for all of their parameters except that in one entry beam_size = 3.0", and in the other entry beam_size = 6.0". The HEASARC has retained both of these entries in its version of this catalog: they have (new) source_number values of 255 and 256. As noted in the reference paper, (original) source numbers below 10,000 relate to those sources found by the AIPS SAD algorithm while those above 10,000 were the sources found and investigated "by hand". To make this distinction more explicit, the HEASARC has added a parameter called source_type which has been set to 'S' for the former SAD-detected sources and to 'H' for the latter hand-selected sources.

Name
The position-based designation of the GOODS-North VLA source, viz., 'GOODS VLA JHHMMSS.ss+DDMMSS.s'. This was created by the HEASARC after consultation with the first author, replacing the source number-based naming convention suggested by the Dictionary of Nomenclature of Celestial Objects.

RA
The Right Ascension of the VLA source in the selected equinox. This was given in J2000.0 equatorial coordinates to a precision of 0.01 seconds of time in the original table.

RA_Error
The uncertainty in the Right Ascension of the VLA source, in seconds of time.

Dec
The Declination of the VLA source in the selected equinox. This was given in J2000.0 equatorial coordinates to a precision of 0.1 arcseconds in the original table.

Dec_Error
The uncertainty in the Declination of the VLA source, in arcseconds.

LII
The Galactic Longitude of the VLA source.

BII
The Galactic Latitude of the VLA source.

SNR
The Signal to Noise Ratio (S/N) of the radio source, defined as the ratio of the observed peak flux density to the local noise.

Flux_1p4_GHz
The observed peak brightness of the 1.4-GHz radio source, in units of milliJanskys per beam (mJy/beam) and uncorrected for primary beam or bandwidth smearing. The units were converted by the HEASARC from the microJanskys per beam (uJy/beam) units in the original table.

Flux_1p4_GHz_Error
The uncertainty in the observed peak brightness of the 1.4-GHz radio source, in units of milliJanskys per beam (mJy/beam). The units were converted by the HEASARC from the microJanskys per beam (uJy/beam) units in the original table.

Int_Flux_1p4_GHz
The total primary beam-corrected flux density of the 1.4-GHz radio source, in units of milliJanskys (mJy). The units were converted by the HEASARC from the microJanskys (uJy) units in the original table.

Int_Flux_1p4_GHz_Error
The uncertainty in the total primary beam-corrected flux density of the 1.4-GHz radio source, in units of milliJanskys (mJy). The units were converted by the HEASARC from the microJanskys (uJy) units in the original table.

Major_Axis
The two-dimensional Gaussian major axis size (FWHM) for the radio source, in arcseconds, if such a fit was the best fit using the authors' criteria for resolved sources. Very extended sources, as shown in Figures 2 and 3 of the reference paper, had their positions, sizes, fluxes, and errors measured interactively using IMVAL and TVSTAT. If the source was not resolved, this parameter is set to 0.0.

Minor_Axis
The two-dimensional Gaussian minor axis size (FWHM) for the radio source, in arcseconds, if such a fit was the best fit using the authors' criteria for resolved sources. Very extended sources, as shown in Figures 2 and 3 of the reference paper, had their positions, sizes, fluxes, and errors measured interactively using IMVAL and TVSTAT. If the source was not resolved, this parameter is set to 0.0.

Position_Angle
The position angle (PA) of the major axis of the two-dimensional Gaussian major axis size (FWHM) for the radio source, in degrees, if such a fit was the best fit using the authors' criteria for resolved sources. If the source was not resolved, this parameter is set to 0.

Maximum_Major_Axis
If the radio source was not resolved, the upper limit to the major axis of the radio source as estimated by JMFIT or SAD, in arcseconds. If the source was resolved, this parameter is set to null.

Beam_Size
The resolution of the map that was used for the measurements for that particular source, in arcseconds: 1.7 arcseconds for the full-resolution maps, 3 and 6 arcsecond resolution maps were also made to recover the full flux of extended sources.

Source_Type
The original source number values encoded the origin of the sources: values below 10,000 related to those sources found by the AIPS SAD algorithm while those above 10,000 were the sources found and investigated "by hand" of the authors. To make this distinction more explicit, the HEASARC has created this flag parameter which has been set to 'S' for the former SAD-detected sources and to 'H' for the latter hand-selected sources.


Contact Person

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

Page Author: Browse Software Development Team
Last Modified: 24-Sep-2013