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10C

The Tenth Cambridge (10C) Survey of Radio Sources

Introduction

The 15.7-GHz, 10C Survey was carried out using the Arcminute Microkelvin Imager (AMI) Large Array (LA), which is operated by the Cavendish Astrophysics Group at Lord’s Bridge, Cambridgeshire. The LA is one of the two AMI arrays (see AMI Consortium: Zwart et al. 2008 for detailed technical information about AMI); it is a radio synthesis telescope comprising eight 13-metre-diameter dishes and is used to observe between frequencies of 13.5 and 18.0 GHz with a resolution of approximately 30 arcsec.

In tandem with the AMI Small Array (SA), the LA is being used to carry out blind surveys of the sky at 15.7 GHz. The SA is designed to be sensitive to larger angular scales than the LA because its primary science goal is to detect previously-unknown galaxy clusters using the Sunyaev-Zel’dovich effect. On the other hand, the LA has been optimised to carry out high-radio-frequency surveys of foreground radio sources.

The first 10C Survey results from an area of ≈ 27 sq. degrees complete to 1 mJy and ≈ 12 sq. degrees complete to 0.5 mJy have now been released. Further information relating to the first 10C data release can be found below, including links to the catalogue, which contains entries for 1897 sources, and to relevant publications.

First Data Release

Technical information about the observing, mapping and source extraction techniques used to collect and analyse the 10C data can be found in AMI Consortium: Franzen et al. (2010).

The first results from the survey, which is the deepest extragalactic radio source survey of any significant extent (> ∼ 0.2 sq. degrees) above 1.4 GHz, including the deep 15.7-GHz source count are contained in AMI Consortium: Davies et al. (2010). Results from 10 survey fields are included in the first data release. For each field, deep and shallow areas have been defined. These regions are bounded by lines of constant RA and declination, which are given in the paper and in the below README file.

In total the shallow areas cover ≈ 27 sq. degrees and the deep areas (which are wholly contained within the shallow areas) ≈ 12 sq. degrees. The 4.6-σ catalogue for the deep and shallow areas is complete (except for a number of circular areas around bright sources, the locations and radii of which are given in the paper and the below README file) to 0.5 and 1 mJy, respectively – the completeness for both areas is estimated to be at least 93 per cent. The catalogue also contains a number of sources which are detected at greater than 4.6 σ but which lie outside the defined regions towards the edges of the 10C raster maps, where the noise level is higher.

The 10C catalogue is available in ASCII and PDF formats. The accompanying README file provides the areas of completeness for the fields and information about the various parameters contained in the catalogue.

Lockman Hole

A detailed study of the radio spectral properties of sources in two fields of the 10C survey in the Lockman Hole, covering 4.6 square degrees, has been carried out. This study used a range of radio data available in the Lockman Hole, including a deep GMRT survey at 610 MHz (available here), a WSRT survey at 1.4 GHz, NVSS and FIRST, to calculate the spectral indices of sources selected at 15.7 GHz from the 10C survey. Full details of this study can be found in Whittam et al. (2013).

The catalogue contains radio spectral indices between 15.7 GHz and 610 MHz and 15.7 GHz and 1.4 GHz for 296 sources selected at 15.7 GHz. Note that this catalogue contains sources which do not appear in the first 10C data release as they are below the completeness limit. A full description of the catalogue is available in the ReadMe file. The catalogue is available here.

 


AMI Large Array

Last modified 21 June 2013

Matthew Davies (m.davies@mrao.cam.ac.uk)
Thomas Franzen (tmof2@mrao.cam.ac.uk)
Elizabeth Waldram (emw1@mrao.cam.ac.uk)
Imogen Whittam (ihw24@mrao.cam.ac.uk)