Browse
this table...

VLACOS3GHZ - VLA-COSMOS 3-GHz Large Project Source Catalog

HEASARC
Archive

Overview

This table contains some of the results from the VLA-COSMOS 3-GHz Large Project based on 384 hours of observations with the Karl G. Jansky Very Large Array (VLA) at 3 GHz (10 cm) toward the 2 square degree Cosmic Evolution Survey (COSMOS) field. The final mosaic reaches a median rms of 2.3 µJy (µJy) beam-1 over the 2 square degrees at an angular resolution of 0.75 arcseconds. To fully account for the spectral shape and resolution variations across the broad (2-GHz) band, the authors imaged all the data with a multiscale, multifrequency synthesis algorithm. In this table, the catalog of 10,830 radio sources down to 5 sigma is presented, out of which 67 are combined from multiple components. Comparing the positions of these 3-GHz sources with those from the Very Long Baseline Array (VLBA)-COSMOS survey, the authors estimate that the astrometry is accurate to 0.01 arcseconds at the bright end (signal-to-noise ratio, S/N3GHz > 20). Survival analysis on these data combined with the VLA-COSMOS 1.4-GHz Joint Project catalog yields an expected median radio spectral index alpha = -0.7. The authors compute completeness corrections via Monte Carlo simulations to derive the corrected 3-GHz source counts. Their counts are in agreement with previously derived 3-GHz counts based on single-pointing (0.087 square degrees) VLA data. In summary, the VLA-COSMOS 3-GHz Large Project simultaneously provides the largest and deepest radio continuum survey at high (0.75") angular resolution to date, bridging the gap between last-generation and next-generation surveys.

The catalog contains sources selected down to a 5-sigma (where sigma ~2.3 µJy/beam) threshold. This catalog can be used for statistical analyses, accompanied with the corrections given in the data & catalog release paper. All completeness and bias corrections and source counts presented in the paper were calculated using this sample. The total fraction of spurious sources in the COSMOS 2 sq.deg. field is below 2.7% within this catalog. However, an increase of spurious sources up to 24% at 5.0 < S/N < 5.5 is present (for details see Sec. 5.2., Fig. 17 and Table 3 of the reference paper). A subsample with a minimal spurious source fraction can be selected by requiring an additional cutoff S/N >= 5.5 for single component sources (MULTI=0). The total fraction of spurious sources in the COSMOS 2 sq.deg. field within such a selected sample is below 0.4%, and the fraction of spurious sources is below 3% even at the lowest S/N of 5.5.


Catalog Bibcode

2017A&A...602A...1S

References

The VLA-COSMOS 3 GHz Large Project: Continuum data and source catalog release.
    Smolcic V., Novak M., Bondi M., Ciliegi P., Mooley K.P., Schinnerer E.,
    Zamorani G., Navarrete F., Bourke S., Karim A., Vardoulaki E., Leslie S.,
    Delhaize J., Carilli C.L., Myers S.T., Baran N., Delvecchio I.,
    Miettinen O., Banfield J., Balokovic M., Bertoldi F., Capak P., Frail D.A.,
    Hallinan G., Hao H., Herrera Ruiz N., Horesh A., Ilbert O., Intema H.,
    Jelic V., Klockner H-R., Krpan J., Kulkarni S.R., McCracken H., Laigle C.,
    Middleberg E., Murphy E., Sargent M., Scoville N.Z., Sheth K.
    <Astron. Astrophys. 602, A1 (2017)>
    =2017A&A...602A...1S        (SIMBAD/NED BibCode)

Provenance

This table was created by the HEASARC in June 2017 based on CDS Catalog J/A+A/602/A1 file table1.dat, the VLA-COSMOS 3-GHz radio source catalog.

Catalog Notes

    1. The maximum source number ID is 10,966 although there are 10,830
        sources. Some IDs were removed by having been joined into
        multi-component sources.
    2. The peak surface brightness of sources [mJy/beam] is not reported,
        but can be obtained by multiplying the SNR by the RMS.
    3. A high number of pixels usually indicates extended or very bright
        sources.
    4. The reported positional errors on resolved and extended sources should
        be considered lower limits.
    5. Multicomponent sources have their and flux errors, and their S/N
        parameter values set to nulls (rather than to -99.0 as in the original
        CDS table).

Additional data information:

    Catalog date: 21-Mar-2016
    Source extractor: BLOBCAT v1.2 (http://blobcat.sourceforge.net/)
    Observations: 384 hours, VLA, S-band (2-4GHz), A+C array, 192 pointings
    Imaging software: CASA v4.2.2 (https://casa.nrao.edu/)
    Imaging algorithm: Multiscale multifrequency synthesis on single pointings
    Mosaic size: 30,000 x 30,000 pixels (3.3 GB)
    Pixel size: 0.2 x 0.2 arcsec2
    Median rms noise in the COSMOS 2 sq.deg.: 2.3uJy/beam
    Beam is circular with FWHM = 0.75 arcsec
    Bandwidth-smearing peak correction: 0% (no corrections applied)
    Resolved criteria: Sint/Speak > 1 + 6*SNR^-1.44
    Total area covered: 2.6 sq.deg.

Parameters

Source_Number
A unique source number ID for the radio source. The maximum source number ID is 10,966 although there are 10,830 sources, as some IDs were removed by joining them into multi-component sources.

Name
The 3-GHz radio source designation using the prefix 'COSMOSVLA3' recommended by the authors in the reference paper, and the J2000.0 truncated coordinates of the radio source, e.g., 'COSMOSVLA3 J095709.33+020940.7'. The HEASARC notes that this source designation has not yet been registered with the Dictionary of Nomenclature of Celestial Objects.

RA
The Right Ascension of the radio source in the selected equinox. This was given in J2000.0 decimal degrees to a precision of 10-6 degrees in the original table.

RA_Error
The RMS uncertainty in the Right Ascension of the radio source, in arcseconds. The reported positional errors on resolved and extended sources should be considered to be lower limits. Multicomponent sources have had their positional and flux errors, and their S/N parameter values set to nulls (rather than to -99.0 as in the original CDS table).

Dec
The Declination of the radio source in the selected equinox. This was given in J2000.0 decimal degrees to a precision of 10-6 degrees in the original table.

Dec_Error
The RMS uncertainty in the Declination of the radio source, in arcseconds. The reported positional errors on resolved and extended sources should be considered to be lower limits. Multicomponent sources have had their positional and flux errors, and their S/N parameter values set to nulls (rather than to -99.0 as in the original CDS table).

LII
The Galactic Longitude of the radio source.

BII
The Galactic Latitude of the radio source.

Flux_3_GHz
The total integrated 30-GHz flux density of the radio source, in mJy (converted by the HEASARC from the µJy units used in the original table). The peak surface brightness of sources [mJy/beam] is not reported, but can be obtained by multiplying the SNR by the RMS.

Flux_3_GHz_Error
The error in the total integrated 30-GHz flux density of the radio source, in mJy (converted by the HEASARC from the µJy units used in the original table). Multicomponent sources have had their positional and flux errors, and their S/N parameter values set to nulls (rather than to -99.0 as in the original CDS table).

RMS_3_GHz
The local RMS noise in the 3-GHz image at the source position, in mJy/beam (converted by the HEASARC from the µJy/beam units used in the original table).

SNR_3_GHz
The signal-to-noise ratio (S/N) of the radio source. Multicomponent sources have had their positional and flux errors, and their S/N parameter values set to nulls (rather than to -99.0 as in the original CDS table).

Number_Pixels
The number of pixels used for the calculation of the integrated flux density of the radio source. A high number of pixels usually indicates an extended or very bright source.

Resolved_Flag
This flag parameter is set to 1 to indicate a resolved source; otherwise, it is set to 0.

Multi_Component_Flag
This flag parameter is set to 1 to indicate a multi-component source; otherwise, it is set to 0.


Contact Person

Questions regarding the VLACOS3GHZ database table can be addressed to the HEASARC User Hotline.

Page Author: Browse Software Development Team
Last Modified: 5-Jul-2017