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AT20G - Australia Telescope 20-GHz (AT20G) Survey Catalog

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Overview

The Australia Telescope 20-GHz Survey (AT20G) is a blind radio survey carried out at 20 GHz with the Australia Telescope Compact Array (ATCA) from 2004 to 2008, and covers the whole sky south of declination 0 degrees. The AT20G source catalogue presented here is an order of magnitude larger than any previous catalogue of high-frequency radio sources, and includes 5890 sources above a 20-GHz flux-density limit of 40 mJy. All AT20G sources have total intensity and polarisation measured at 20 GHz, and most sources south of declination -15 degrees also have near-simultaneous flux-density measurements at 5 and 8 GHz. A total of 1559 sources were detected in polarised total intensity at one or more of the three frequencies.

The completeness of the AT20G source catalog is 91% above 100 mJy/beam and 79% above 50 mJy/beam in regions south of Declination -15 degrees. North of -15 degrees, some observations of sources between 14 and 20 hours in RA were lost due to bad weather and could not be repeated, so the catalog completeness is lower in this region. Each detected source was visually inspected as part of the authors' quality control processs, and so the reliability of the final catalog is essentially 100%.


Catalog Bibcode

2010MNRAS.402.2403M

References

The Australia Telescope 20GHz Survey (AT20G), Version XX October 2009.
    Murphy T., Sadler E.M., Ekers R.D., Massardi M., Hancock P.J., Mahony E.,
    Ricci R., Burke-Spolaor S., Calabretta M., Chhetri R., De Zotti G.,
    Edwards P.G., Ekers J.A., Jackson C.A., Kesteven M.J., Lindley E.,
    Newton-McGee K., Phillips C., Roberts P., Sault R.J., Staveley-Smith L.,
    Subrahmanyan R., Walker M.A., Wilson W.E.
   <Mon. Not. R. Astron. Soc. 402, 2403 (2010)>
   =2010MNRAS.402.2403M

Provenance

This table was created by the HEASARC in March 2010 based on the CDS Catalog J/MNRAS/402/2403/ file at20gcat.dat.

Parameters

Name
The IAU-style AT20G radio source designation (AT20G JHHMMSS+DDMMSS). Notice that the CDS Dictionary of Nomenclature of Celestial Objects recommends a more detailed naming convention (AT20G JHHMMSS.s+DDMMSS) than the one used here.

RA
The Right Ascension of the radio source in the selected equinox. The RA was given in J2000.0 coordinates to a precision of 0.01 seconds of time in the original table. The average error in RA is 0.9 arcseconds (see Section 4 of the reference paper for a discussion of how the mean errors were derived).

Dec
The Declination of the radio source in the selected equinox. The Dec was given in J2000.0 coordinates to a precision of 0.1 arcseconds in the original table. The average error in Dec is 1.0 arcseconds (see Section 4 of the reference paper for a discussion of how the mean errors were derived).

LII
The Galactic Longitude of the radio source.

BII
The Galactic Latitude of the radio source.

Flux_1p5_cm
The flux density of the radio source at 20 GHz, in mJy. For resolved sources indicated by a value of 'e' for the corresponding source_flags parameter, this is the integrated flux density. See Sec 3.3.2 of the reference paper for a detailed discussion of the calculation of fluxes for extended sources.

Flux_1p5_cm_Error
The RMS uncertainty of the corresponding flux density, in mJy.

Flux_3p5_cm
The flux density of the radio source at 8 GHz, in mJy. For resolved sources indicated by a value of 'e' for the corresponding source_flags parameter, this is the integrated flux density. See Sec 3.3.2 of the reference paper for a detailed discussion of the calculation of fluxes for extended sources.

Flux_3p5_cm_Error
The RMS uncertainty of the corresponding flux density, in mJy.

Flux_6_cm
The flux density of the radio source at 5 GHz, in mJy. For resolved sources indicated by a value of 'e' for the corresponding source_flags parameter, this is the integrated flux density. See Sec 3.3.2 of the reference paper for a detailed discussion of the calculation of fluxes for extended sources.

Flux_6_cm_Error
The RMS uncertainty of the corresponding flux density, in mJy.

Observing_Epochs
This parameter contains flags which indicate the epochs of the follow-up observations at 20, 8, and 5 GHz, respectively, i.e., the 3 digits give the epoch code for the 3 frequencies (more details are given in in Table 3 of the paper),coded as follows:


  Epoch   Dec.     Freq1  Freq2  Array  Beam1     Beam2       Dates       Reason
         (deg)     (MHz)  (MHz)  Conf. (arcsec)  (arcsec)

    1  -50 to -30  18752  21056  H214  10.8x10.8   ---     2004 Oct 21-27     C
    1  -50 to -30   4800   8640  1.5C   8.3x12.8  4.6x7.13 2004 Nov 04-08     O
    2  -90 to -50  18752  21056  H168  13.9x13.9   ---     2005 Oct 27-31     C
    2  -90 to -50   4800   8640  1.5C   8.3x 8.8  4.6x4.9  2005 Nov 12-15     O
    3  -90 to -30  18752  21056  H214  10.8x10.8   ---     2006 Apr 29-May 03 R
    3  -90 to -30   4800   8640  1.5D   8.3x 9.5  4.6x5.3  2006 Jun 19-23     R,O
    4  -30 to -15  18752  21056  H214   2.0x 5.1   ---     2006 Oct 14-17     C
    4  -30 to -15   4800   8640  1.5B   8.3x21.1  4.6x11.7 2006 Nov 9-12      O
    5  -90 to -15  18752  21056  H214  10.8x10.8   ---     2007 May 11-16     R
    5  -90 to -15   4800   8640  1.5C   8.3x21.1  4.6x11.7 2007 May 4-10      R,O
    6  -90 to 0    18752  21056  H214  10.8x10.8   ---     2007 Oct 26-30     C,R
    7  -15 to 0    18752  21056  H75   33.9x33.9   ---     2008 Aug 22-26     R
  

where in the last column, 'C' means follow-up observations at 20GHz, 'O' means observations at 5 and 8GHz, and 'R' means a repeat of previous bad quality observations.

Quality_Flag
This parameter contains a flag which indicates the source quality: 'g' = good (5501 sources), or 'p' = poor (389 sources). A poor-quality flag indicates that there were lower quality data in that observations, or that, in the case of an extended source, the triple product flux (see Section 3.3.1 of the reference paper) was used rather than the shortest-line flux. Hence, the flux density measurement for poor-quality sources may not be as reliable.

Source_Flags
This parameter contains flags which indicate source classification information. Possible values are as follows:

        e = extended source so that the shortest baseline flux has been used
        h = source identified as a Galactic HII region (see Section 5.4)
        p = source identified as a Galactic planetary nebula (see Section 5.4)
        m = source identified as part of the Magellanic Clouds (see Sect. 5.3)
        l = source has no match in the low frequency surveys, NVSS and SUMSS
            (see Section 8.4)
        b = source is large and extended (see Table 6)
  

Pol_Flux_1p5_cm_Limit
This flag is set to '<' if the corresponding polarized flux density is an upper limit to the actual value.

Pol_Flux_1p5_cm
The polarized flux density of the radio source at 20 GHz, in mJy.

Pol_Flux_1p5_cm_Error
The RMS uncertainty in the corresponding polarized flux density, in mJy.

Pol_Percent_1p5_cm_Limit
This flag is set to '<' if the corresponding fractional polarization is an upper limit to the actual value.

Pol_Percent_1p5_cm
The fractional polarization of the radio source at 20 GHz, in percent.

Pol_Angle_1p5_cm
The polarization position angle of the radio source at 20 GHz, in degrees.

Pol_Flux_3p5_cm_Limit
This flag is set to '<' if the corresponding polarized flux density is an upper limit to the actual value

Pol_Flux_3p5_cm
The polarized flux density of the radio source at 8 GHz, in mJy.

Pol_Flux_3p5_cm_Error
The RMS uncertainty in the corresponding polarized flux density, in mJy.

Pol_Percent_3p5_cm_Limit
This flag is set to '<' if the corresponding fractional polarization is an upper limit to the actual value.

Pol_Percent_3p5_cm
The fractional polarization of the radio source at 8 GHz, in percent.

Pol_Angle_3p5_cm
The polarization position angle of the radio source at 8 GHz, in degrees.

Pol_Flux_6_cm_Limit
This flag is set to '<' if the corresponding polarized flux density is an upper limit to the actual value

Pol_Flux_6_cm
The polarized flux density of the radio source at 5 GHz, in mJy.

Pol_Flux_6_cm_Error
The RMS uncertainty in the corresponding polarized flux density, in mJy.

Pol_Percent_6_cm_Limit
This flag is set to '<' if the corresponding fractional polarization is an upper limit to the actual value.

Pol_Percent_6_cm
The fractional polarization of the radio source at 5 GHz, in percent.

Pol_Angle_6_cm
The polarization position angle of the radio source at 5 GHz, in degrees.


Contact Person

Questions regarding the AT20G database table can be addressed to the HEASARC User Hotline.

Page Author: Browse Software Development Team
Last Modified: 29-Mar-2010