AMI10C15GZ - 10C Survey at 15.7 GHz Radio Source Catalog

Overview

In a previous paper (AMI Consortium 2011, MNRAS, 415, 2699: Paper I), the observational, mapping and source-extraction techniques used for the Tenth Cambridge (10C) Survey of Radio Sources were described. Here, the first results from the survey, carried out using the Arcminute Microkelvin Imager (AMI) Large Array (LA) at an observing frequency of 15.7 GHz, are presented. The survey fields cover an area of ~ 27 deg² to a flux-density completeness of 1 mJy. Results for some deeper areas, covering ~ 12 deg², which are wholly contained within the total areas and complete to 0.5 mJy, are also presented. The completeness for both areas is estimated to be at least 93 per cent. The 10C survey is the deepest radio survey of any significant extent (>~ 0.2 deg²) above 1.4 GHz.

The 10C source catalogue contains 1897 entries detected above a flux density threshold of > 4.62 sigma, and is available here and at the authors' web site http://www.mrao.cam.ac.uk/surveys/10C. The source catalog has been combined with that of the Ninth Cambridge Survey to calculate the 15.7-GHz source counts. A broken power law is found to provide a good parametrization of the differential count between 0.5 mJy and 1 Jy. The measured source count has been compared with that predicted by de Zotti et al. (2005, A&A, 431, 893, and the model is found to display good agreement with the data at the highest flux densities. However, over the entire flux-density range of the measured count (0.5 mJy to 1 Jy), the model is found to underpredict the integrated count by ~ 30 per cent. Entries from the source catalog have been matched with those contained in the catalogues of the NRAO VLA Sky Survey and the Faint Images of the Radio Sky at Twenty-cm survey (both of which have observing frequencies of 1.4 GHz). This matching provides evidence for a shift in the typical 1.4-GHz spectral index to 15.7-GHz spectral index of the 15.7-GHz-selected source population with decreasing flux density towards sub-mJy levels - the spectra tend to become less steep.

Automated methods for detecting extended sources, developed in Paper I, have been applied to the data; ~ 5 per cent of the sources are found to be extended relative to the LA-synthesized beam of ~ 30 arcsec. Investigations using higher resolution data showed that most of the genuinely extended sources at 15.7 GHz are classical doubles, although some nearby galaxies and twin-jet sources were also identified.

Catalog Bibcode

2011MNRAS.415.2708A

References

10C survey of radio sources at 15.7 GHz - II. First results
    AMI Consortium: Davies M.L., Franzen T.M.O., Waldram E.M., Grainge K.J.B.,
    Hobson M.P., Hurley-Walker N., Lasenby A., Olamaie M., Pooley G.G.,
    Riley J.M., Rodriguez-Gonzalvez C., Saunders R.D.E., Scaife, A.M.M.,
    Schammel, M.P., Scott, P.F., Shimwell, T.W., Titterington, D.J.,
    Zwart, J.T.L.
   <Mon. Nat. R.A.S. 415, 2708 (2011)>
   =2011MNRAS.415.2708A

Provenance

This table was created by the HEASARC in August 2011 based on an electronic version of Table 1 of the reference paper which was obtained from the 10C Survey web site http://www.mrao.cam.ac.uk/surveys/10C/.

Parameters

Name
The position-based source designation recommended by the authors using the CDS Dictionary of Nomenclature of Celestial Objects style, viz., '10C HHMMSS+DDMMSS', where the numerical part of the name is the truncated J2000.0 position of the radio source (to 1 second of time in RA and 1 arcsecond in Declination).

Group_Name
The group name, if any, which includes overlapping sources, where the group is named after the source in the group with the highest peak flux density.

Number_In_Group
The number of objects in the group if the source is in a group (if not, it is left blank.

RA
The Right Ascension of the source peak flux density in the selected equinox. This was given in J2000.0 equatorial coordinates to a precision of 0.1 seconds of time in the original table. The positional errors in both RA and Dec, for a source detected at the 5-sigma level, are estimated by the authors to be 3-4 arcseconds.

Dec
The Declination of the source peak flux density in the selected equinox. This was given in J2000.0 equatorial coordinates to a precision of 1 arcsecond in the original table. The positional errors in both RA and Dec, for a source detected at the 5-sigma level, are estimated by the authors to be 3-4 arcseconds.

LII
The Galactic Longitude of the source peak flux density.

BII
The Galactic Latitude of the source peak flux density.

Flux_2_cm
The peak flux density of the source, in milliJanskies per beam (mJy/beam).

Flux_2_cm_Error
The uncertainty in the peak flux density of the source, in milliJanskies per beam (mJy/beam).

RA_Centroid
The Right Ascension of the centroid of the radio source (relevant for extended sources) in the selected equinox. This was given in J2000.0 equatorial coordinates to a precision of 0.1 seconds of time in the original table.

Dec_Centroid
The Declination of the centroid of the radio source (relevant for extended sources) in the selected equinox. This was given in J2000.0 equatorial coordinates to a precision of 1 arcsecond in the original table.

Int_Flux_2_cm
The integrated flux density of the source, in milliJanskies (mJy).

Int_Flux_2_cm_Error
The uncertainty in the integrated flux density of the source, in milliJanskies (mJy).

Critical_Major_Axis
The critical value of the radio source major axis, i.e., the value above which the source is defined as extended, having deconvolved the telescope's point-source response from the fitted 2D Gaussian, in arcseconds.

Major_Axis
The major axis of the radio source after the deconvolution, in arcseconds.

Minor_Axis
The minor axis of the radio source after the deconvolution, in arcseconds. This is left blank for sources classified as point-like.

Position_Angle
The position angle of the major axis of the radio source after the deconvolution, in degrees. This is left blank for sources classified as point-like.

Source_Type
The flag parameter indicates whether the source is point-like ('P') or extended ('E').

Source_Flag
This flag parameter, if set to 'Y', indicates that the error from the approximation of the point-source response is significant, and, consequently, that the results from the Gaussian fitting should be treated with caution.

Survey_Region
This flag parameter indicates the region of the survey in which the source falls: 'D' if in the deep survey region, 'S' if in the shallow survey region, and 'N' if it is in neither of these regions.

Contact Person

Questions regarding the AMI10C15GZ database table can be addressed to the HEASARC User Hotline.

Page Author: Browse Software Development Team
Last Modified: Wednesday, 17-Aug-2011 10:34:26 EDT