J/MNRAS/462/917 The Super-CLASS GMRT catalogue - SCG (Riseley+, 2016)
Deep observations of the Super-CLASS super-cluster at 325 MHz with the GMRT:
the low-frequency source catalogue.
Riseley C.J., Scaife A.M.M., Hales C.A., Harrison I., Birkinshaw M.,
Battye R.A., Beswick R.J., Brown M.L., Casey C.M., Chapman S.C.,
Demetroullas C., Hung C.-L., Jackson N.J., Muxlow T., Watson B.
<Mon. Not. R. Astron. Soc. 462, 917 (2016)>
=2016MNRAS.462..917R 2016MNRAS.462..917R (SIMBAD/NED BibCode)
ADC_Keywords: Surveys ; Clusters, galaxy ; Galaxies, radio
Keywords: surveys - radio continuum: general
Abstract:
We present the results of 325MHz Giant Metrewave Radio Telescope
observations of a supercluster field, known to contain five Abell
clusters at redshift z∼0.2. We achieve a nominal sensitivity of
34uJy/beam towards the phase centre. We compile a catalogue of 3257
sources with flux densities in the range 183uJy-1.5Jy within the
entire ∼6.5deg2 field of view. Subsequently, we use available survey
data at other frequencies to derive the spectral index distribution
for a sub-sample of these sources, recovering two distinct populations
- a dominant population which exhibit spectral index trends typical of
steep-spectrum synchrotron emission, and a smaller population of
sources with typically flat or rising spectra. We identify a number of
sources with ultrasteep spectra or rising spectra for further
analysis, finding two candidate high-redshift radio galaxies and three
gigahertz-peaked-spectrum radio sources. Finally, we derive the
Euclidean-normalized differential source counts using the catalogue
compiled in this work, for sources with flux densities in excess of
223uJy. Our differential source counts are consistent with both
previous observations at this frequency and models of the
low-frequency source population. These represent the deepest source
counts yet derived at 325MHz. Our source counts exhibit the well-known
flattening at mJy flux densities, consistent with an emerging
population of star-forming galaxies; we also find marginal evidence of
a downturn at flux densities below 308uJy, a feature so far only seen
at 1.4GHz.
Description:
The Super-CLASS GMRT (SCG) catalogue is the low-frequency counterpart
of the Super-Cluster Assisted Shear Survey. It is a survey at
13-arcsec resolution, with a limiting 5σ flux density of 170uJy.
The catalogue comprises 3257 sources.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
scg.dat 111 3257 The 325MHz source population of the Super-CLASS
field (full table 4)
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Byte-by-byte Description of file: scg.dat
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Bytes Format Units Label Explanations
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1- 7 A7 --- --- [SCG_325]
8- 21 A14 --- SCG Designation (JHHMMSS+SSMMSS)
23- 24 I2 h RAh Right ascension (J2000)
26- 27 I2 min RAm Right ascension (J2000)
29- 33 F5.2 s RAs Right ascension (J2000)
34 A1 --- DE- Declination sign (J2000)
35- 36 I2 deg DEd Declination (J2000)
38- 39 I2 arcmin DEm Declination (J2000)
41- 45 F5.2 arcsec DEs Declination (J2000)
47- 52 F6.2 mJy Si Integrated flux density at 325MHz
54- 59 F6.2 mJy e_Si Integrated flux density uncertainty
61- 67 F7.2 mJy/beam Sp Peak flux density at 325MHz
69- 74 F6.2 mJy/beam e_Sp Peak flux density uncertainty
76- 81 F6.2 arcsec MajDiam ? Deconvolved major axis
83- 87 F5.2 arcsec MinDiam ? Deconvolved minor axis
89- 94 F6.2 deg PA ? Deconvolved position angle
96- 99 F4.2 arcsec e_MajDiam ? Deconvolved major axis uncertainty
101-104 F4.2 arcsec e_MinDiam ? Deconvolved minor axis uncertainty
106-111 F6.2 deg e_PA ? Deconvolved p.a. uncertainty
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Acknowledgements:
Christopher John Riseley, c.j.riseley(at)manchester.ac.uk
(End) Christopher Riseley [Univ. Manchester], Patricia Vannier [CDS] 28-Jun-2016