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GMRTELAIN1 - Giant Metrewave Radio Telescope ELAIS-N1 Field 610-MHz Radio Source Catalog

HEASARC
Archive

Overview

This table contains a source catalog based on observations of the European Large-Area ISO Survey-North 1 (ELAIS-N1) field taken at 610 MHz with the Giant Metrewave Radio Telescope. Nineteen pointings were observed, covering a total area of ~ 9 square degrees with a resolution of 6 x 5arcsec2, position angle of +45 degrees. Four of the pointings were deep observations with an rms of ~ 40 microJansy (uJy) before primary beam correction, with the remaining fifteen pointings having an rms of ~ 70 uJy. The techniques used for data reduction and production of a mosaicked image of the region are described in the reference paper, where the final mosaic, along with a catalog of 2500 sources detected above a 6-sigma thereshold, are presented. This work complements the large amount of optical and infrared data already available on the region. In their paper, the authors calculate 610-MHz source counts down to 270 uJy, and find further evidence for the turnover in differential number counts below 1 mJy, previously seen at both 610 MHz and 1.4 GHz. For further details of the surveys and data analysis procedures, please refer to the published paper.

This table contains the ELAIS-N1 catalog of 2500 detected 610-MHz radio sources.


Catalog Bibcode

2008MNRAS.383...75G

References

A 610-MHz survey of the ELAIS-N1 field with the Giant Metrewave Radio
Telescope. Observations, data analysis and source catalogue.
    Garn T., Green D.A., Riley J.M., Alexander P.
   <Mon. Not. R. Astron. Soc. 383, 75 (2008)>
   =2008MNRAS.383...75G

Provenance

This table was created by the HEASARC in February 2012 based on CDS Catalog J/MNRAS/383/75 file catalog.dat.

Parameters

Name
The name of the radio source using the IAU-style designation for the source based on the truncated J2000.0 equatorial coordinates of its centroid, viz., 'GMRTEN1 JHHMMSS.s+DDMMSS', as registered with the CDS Dictionary of Nomenclature of Celestial Objects, where the GMRTEN1 prefix stands for 'Giant Metrewave Radio Telescope ELAIS-N1'.

RA
The Right Ascension of the source in the selected equinox, calculated using first moments of the relevant pixel brightnesses to give the centroid position. This was given in J2000.0 coordinates to a precision of 0.01 seconds of time in the original table.

Dec
The Declination of the source in the selected equinox, calculated using first moments of the relevant pixel brightnesses to give the centroid position. This was given in J2000.0 coordinates to a precision of 0.1 arcseconds in the original table.

LII
The Galactic Longitude of the radio source centroid.

BII
The Galactic Latitude of the radio source centroid.

Flux_610_MHz
The radio brightness of the peak pixel in the 610-MHz radio source, in mJy/beam.

RMS_610_MHz
The local rms noise near the source position, in mJy/beam (converted by the HEASARC from the uJy/beam units used in the original table).

Int_Flux_610_MHz
The integrated flux density of the 610-MHz radio source, in mJy.

Int_Flux_610_MHz_Error
The error in the integrated flux density of the 610-MHz radio source, in mJy.

Centroid_X_Pixel
The X pixel coordinate from the mosaic image which was closest to the source centroid.

Centroid_Y_Pixel
The Y pixel coordinate from the mosaic image which was closest to the source centroid.

SExtractor_DB_Flag
The SEXTRACTOR (Source Extractor) deblended object flag coded as follows:

     1 = where a nearby bright source may be affecting the calculated flux
     2 = where a source has been deblended into two or more components
         from a single initial 'island' of flux
     3 = when both conditions 1 and 2 apply
  
There are 115 sources present in the catalog with non-zero deblend flags (note that, in the reference paper, the authors state that there are 232 such sources: the HEASARC does not know the reason fot this discrepancy), and it is necessary to examine the GMRT mosaic image, available at http://www.mrao.cam.ac.uk/surveys/GMRT/ELAIS-N1/, to distinguish between the case where one extended object has been represented by 2 or more entries, compared to the case where two astronomically different objects are actually present.

Contact Person

Questions regarding the GMRTELAIN1 database table can be addressed to the HEASARC User Hotline.

Page Author: Browse Software Development Team
Last Modified: 9-Feb-2012