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ATLBS1P4GH - Australia Telescope Low-Brightness Survey Source Catalog



The Australia Telescope Low-brightness Survey (ATLBS) regions have been mosaic imaged at a radio frequency of 1.4 GHz with 6 arcseconds angular resolution and 72 microJansky per beam (uJy/beam) rms noise. The images (centered at RA 00h 35m 00s, Dec -67o 00' 00" and RA 00h 59m 17s, Dec -67o 00' 00", J2000 epoch) cover 8.42 deg2 sky area and have no artifacts or imaging errors above the image thermal noise. Multi-resolution radio and optical r-band images (made using the 4 m CTIO Blanco telescope) were used to recognize multi-component sources and prepare a source list of 1366 1.4-GHZ sources; the detection threshold was 0.38 mJy in a low-resolution radio image made with beam FWHM of 50 arcseconds. Radio source counts in the flux density range 0.4-8.7 mJy are estimated, with corrections applied for noise bias, effective area correction, and resolution bias. The resolution bias is mitigated using low-resolution radio images, while effects of source confusion are removed by using high-resolution images for identifying blended sources. Below 1 mJy the ATLBS counts are systematically lower than the previous estimates. Showing no evidence for an upturn down to 0.4 mJy, they do not require any changes in the radio source population down to the limit of the survey. The work suggests that automated image analysis for counts may be dependent on the ability of the imaging to reproduce connecting emission with low surface brightness and on the ability of the algorithm to recognize sources, which may require that source finding algorithms effectively work with multi-resolution and multi-wavelength data. The work underscores the importance of using source lists - as opposed to component lists - and correcting for the noise bias in order to precisely estimate counts close to the image noise and determine the upturn at sub-mJy flux density.

Catalog Bibcode



High-resolution Imaging of the ATLBS Regions: The Radio Source Counts
    Thorat K., Subrahmanyan R., Saripalli L., Ekers R.D.
   <Astrophys. J. 762, 16 (2013)>


This table was created by the HEASARC in April 2013 based on an electronic version of Table 2 from the reference paper that was obtained from the ApJ web site..


The source designation as given in the reference paper using the prefix 'ATLBS' for 'Australia Telescope Low-Brightness Survey' together with the J2000.0 equatorial coordinates of the source centroid, e.g., 'ATLBS JHHMM.m+DDMM'.

The Right Ascension of the centroid of the radio emission in the selected equinox. This was given J2000.0 coordinates to a precision of 0.01 seconds of time in the original table.

The Declination of the centroid of the radio emission in the selected equinox. This was given J2000.0 coordinates to a precision of 0.1 arcseconds in the original table.

The Galactic Longitude of the centroid of the radio emission.

The Galactic Latitude of the centroid of the radio emission.

The integrated 1.4-GHz flux density of the radio source, in mJy.

The 1.4-GHz source type based on the high-resolution image:

      C = a `complex' source;
      G = a single component Gaussian;
      P = an unresolved source;
      M = a source undetected in the high-resolution image.

The number of components in the source: this is given only for complex sources.

Contact Person

Questions regarding the ATLBS1P4GH database table can be addressed to the HEASARC User Hotline.
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Last Modified: Monday, 01-Apr-2013 16:28:24 EDT