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GMRT4F150M - Giant Metrewave Radio Telescope Field I 150-MHz Radio Source Catalog

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Overview

Foreground removal is a major challenge for detecting the redshifted 21-cm neutral hydrogen (HI) signal from the Epoch of Reionization. The authors have used 150-MHz Giant Metrewave Radio Telescope (GMRT) observations to characterize the statistical properties of the foregrounds in four different fields of view. The observational data were used to assess point source subtraction. Considering the brightest source (~1 Jy) in each field, the authors find that the residual artefacts are less than 1.5% in the most sensitive field (FIELD I). Considering all the sources in the fields, they find that the bulk of the image is free of artefacts, the artefacts being localized to the vicinity of the brightest sources. The authors have used FIELD I, which has an rms noise of 1.3 mJy beam-1, to study the properties of the radio source population to a limiting flux of 9 mJy. The differential source count is well fitted with a single power law of slope -1.6. They find there is no evidence for flattening of the source counts towards lower flux densities which suggests that source population is dominated by the classical radio-loud active galactic nuclei.

The authors have observed FIELD I in GMRT Time Allocation Committee (GTAC) cycle 15 in 2008 January, whereas FIELD II and FIELD III were observed in cycle 17 during 2010 February. These target fields were selected at high Galactic latitudes (b > 10o) which were up at night time during the GTAC cycles 15 and 17, and which contain relatively few bright sources (>= 0.3 Jy) in the 1400 MHz NRAO VLA Sky Survey (NVSS). Finally, FIELD IV was observed in cycle 8 (2005 June). Full details of these 4 observations are given in Table 1 of the reference paper.

This table contains the 150-MHz source catalog for the most sensitive observation, namely the 9.8-hour observation of Field I (centered on J2000.0 RA and Dec of 5h 30m 00s, +60o 00' 00"), which was made on 2008 January 8.


Catalog Bibcode

2012MNRAS.426.3295G

References

Characterizing foreground for redshifted 21cm radiation:
150MHz Giant Metrewave Radio Telescope observations.
    Ghosh A., Prasad J., Bharadwaj S., Ali Sk.S., Chengalur J.N.
   <Mon. Not. R. Astron. Soc., 426, 3295-3314 (2012)>
   =2012MNRAS.426.3295G    (SIMBAD/NED BibCode)

Provenance

This table was created by the HEASARC in September 2013 based on CDS Catalog J/MNRAS/426/3295 file tablea1.dat

Parameters

Name
The J2000.0 position-based designation of the 150-MHz source, viz. '[GPB2012] JHHMMSS.s+DDMMSS.s'. The HEASARC has replaced the 'GMRT' prefix used in the original paper (this usage is deprecated by the Dictionary of Nomenclature of Celestial Objects) with the '[GPB2012]' prefix standing for the first 3 authors of the paper (Ghosh, Prasad, Bharadwaj) and the date of publication (2012).

RA
The Right Ascension of the GMRT 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.

Dec
The Declination of the GMRT source in the selected equinox. This was given in J2000.0 equatorial coordinates to a precision of 0.01 arcseconds in the original table.

LII
The Galactic Longitude of the GMRT source.

BII
The Galactic Latitude of the GMRT source.

Flux_150_MHz
The observed peak flux density of the 150-MHz radio source, in units of milliJanskys per beam (mJy/beam).

Flux_150_MHz_Error
The local noise in the vicinity of the 150-MHz radio source, in units of milliJanskys per beam (mJy/beam).

Int_Flux_150_MHz
The integrated flux density of the 150-MHz radio source, in units of milliJanskys (mJy).

Int_Flux_150_MHz_Error
The uncertainty in the integrated flux density of the 150-MHz radio source, in units of milliJanskys (mJy).


Contact Person

Questions regarding the GMRT4F150M database table can be addressed to the HEASARC User Hotline.

Page Author: Browse Software Development Team
Last Modified: 27-Sep-2013