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CRATESOCRAP - OCRA-p Survey of a Subset of CRATES Sources

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Overview

Knowledge of the population of radio sources in the range ~ 2-200 GHz range is important for understanding their effects on measurements of the cosmic microwave background power spectrum. This table contains measurements of the 30-GHz flux densities of 605 radio sources from the Combined Radio All-sky Targeted Eight-GHz Survey (CRATES), which have been made with the One Centimetre Receiver Array-prototype (OCRA-p) on the Torun 32-m telescope. The flux densities of sources that were also observed by Wilkinson Microwave Anisotropy Probe (WMAP) and previous OCRA surveys are in broad agreement with those reported here, however a number of sources display intrinsic variability. The authors find a good correlation between the 30 GHz and Fermi gamma-ray flux densities for sources in common. In their paper, they examine the radio spectra of all observed sources and report a number of gigahertz-peaked and inverted spectrum sources. These measurements will be useful for comparison to those from the Low Frequency Instrument of the Planck satellite, which will make some of its most sensitive observations in the region covered here.

The selection criteria for the subsample of CRATES sources observed by the OCRA-p are given in Section 2 of the reference paper (q.v.). Plots of the measurements of each source over time and the aggregated source spectra between 26 MHz and 150 GHz are available online at the authors' web site: http://www.jodrellbank.manchester.ac.uk/research/ocra/crates/.


Catalog Bibcode

2011MNRAS.410.2690P

References

One Centimetre Receiver Array-prototype observations of the CRATES sources
at 30 GHz
    Peel M.W., Gawronski M.P., Battye R.A., Birkinshaw, M., Browne I.W.A.,
    Davis R.J., Feiler R., Kus A.J., Lancaster K., Lowe S.R.,
    Pazderka B.M., Pazderski E., Roukema B.F., Wilkinson P.N.
   <Mon. Not. R.A.S. 410, 2690 (2011)>
   =2011MNRAS.410.2690P

Provenance

This table was created by the HEASARC in May 2011 based on an electronic version of Table 3 of the reference paper which was obtained from the authors' web site http://www.jodrellbank.manchester.ac.uk/research/ocra/crates/. Notice that the version here is the 10-Jan-2011 version which contains corrections to the 30-GHz flux densities and their errors of ~ 1% in the calibration and the application of the gain-elevation curve.

Parameters

Name
The source designation in the generic style recommended by the Dictionary of Nomenclature of Celestial Objects, using the '[PGB2011]' prefix (for Peel, Gawronski, Battye 2011) and the J2000.0 equatorial coordinates truncated to 1 minute of time and 1 arcminute, e.g., '[PGB2011] J0954+7435'. No prefix is specified in the reference paper. By definition, these are all CRATES sources, but the CRATES source designation is higher precision in both coordinates: for example, the CRATES designation for this source is 'CRATES J095447+743549', hence the HEASARC created the '[PGB2011]' prefix.

RA
The Right Ascension of the pointing for the 30-GHz observation in the selected equinox: this is that of the corresponding CRATES source, except for CRATES sources that have multiple components for which it is that of the brightest component. The position was given in J2000.0 equatorial coordinates to a precision of 0.1 seconds of time in the original table. For comparison, the OCRA beam is 1.2 arcminutes.

Dec
The Declination of the pointing for the 30-GHz observation in the selected equinox: this is that of the corresponding CRATES source, except for CRATES sources that have multiple components for which it is that of the brightest component. The position was given in J2000.0 equatorial coordinates to a precision of 0.1 arcseconds in the original table. For comparison, the OCRA beam is 1.2 arcminutes

LII
The Galactic Longitude of the 30-GHz pointing.

BII
The Galactic Latitude of the 30-GHz pointing.

Flux_20_cm
The flux density of the corresponding source in the CRATES Catalog at 1.4 GHz, in mJy.

Flux_6_cm
The flux density of the corresponding source in the CRATES Catalog at 4.8 GHz, in mJy.

Flux_3p6_cm
The flux density of the corresponding source in the CRATES Catalog at 8.4 GHz, in mJy.

Flux_1_cm
The flux density of the source at 30 GHz as measured by the OCRA-p, in mJy.

Flux_1_cm_Error
The uncertainty in the flux density of the source at 30 GHz as measured by the OCRA-p, in mJy. The methodology used for the OCRA-p flux density error calculation is discussed in Section 3 of the reference paper.

Notes
This parameter can contain flags with various notes on the source properties. From an inspection of the NVSS (Condon et al. 1998, AJ, 115, 1693), Faint Images of the Radio Sky at Twenty Centimeters (FIRST; Becker, White and Helfand 1995, ApJ, 450, 559) and CLASS (Browne et al. 2003, MNRAS, 341, 13; Myers et al. 2003, MNRAS, 341, 1) data, it is clear that the majority of the CRATES sources are unresolved. A number do, however, show extension and/or multiple components; these are marked with a flag value of 'e'. Sources where multiple components listed in CRATES have been merged together are denoted by 'NC', where 'N' is the number of components. WMAP sources (Gold et al. 2011, ApJS, 192, 15) are marked with a 'w', CJF sources (Taylor et al. 1996, ApJS, 107, 37; Lowe et al. 2007, A&A. 474, 1093) are marked with a 'c' and Fermi point sources (Abdo et al. 2010, ApJS, 188, 405) are marked with an 'f' (see Section 5 of the reference paper for a fuller discussion of these issues). Potential gigahertz-peaked spectrum (GPS) sources are marked with a 'g (see Section 6 of the reference paper for a fuller discussion). The authors also note that there are two CLASS lens systems within the sample, J1609+6532 and J1938+6648 (Browne et al. 2003, MNRAS, 341, 13).

There are 42 sources that appear variable within the OCRA measurements; these are marked with a 'v'. Sources were identified as variable if they were reasonably strong (> 20 mJy) and had two measurements which were 25% higher than the mean. Although sources with two measurements that are 25% lower than the mean could also be variable sources, these would be more contaminated by any sources with measurements that suffer from bad telescope pointing (and hence a reduced measured flux density) that have not been flagged. As such, the authors did not include these in the list of variable sources.


Contact Person

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

Page Author: Browse Software Development Team
Last Modified: 28-Aug-2012