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CRATES - CRATES Flat-Spectrum Radio Source Catalog

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Overview

The authors have assembled an 8.4 GHz survey of bright, flat-spectrum (alpha > -0.5) radio sources with nearly uniform extragalactic (|b| > 10 degrees) coverage for sources brighter than a 4.8 GHz flux density S_4.8GHz = 65 mJy. The catalog is assembled from existing observations (especially the Cosmic Lens All-Sky Survey, CLASS, and the Wright et al. PMN-CA survey), augmented by reprocessing of archival VLA and ATCA data and by new observations to fill in coverage gaps. The authors refer to this program as CRATES, the Combined Radio All-Sky Targeted Eight-GHz Survey. The resulting catalog provides precise positions, subarcsecond structures, and spectral indices for some 11,000 sources. The authors describe the morphology and spectral index distribution of the sample and comment on the survey's power to select several classes of interesting sources, especially high-energy blazars. Comparison of CRATES with other high-frequency surveys also provides unique opportunities for identification of high-power radio sources.

This table contains 14467 entries, where each entry corresponds to an 8.4-GHz counterpart source (or absence thereof) to one of 11,131 4.8-GHz sources. The number of entries exceeds the number of 4.8-GHz sources because there are many cases in which there are multiple (from 2 - 20) 8.4-GHz counterparts to a single 4.8-GHz source. There are also 762 entries in which no 8.4-GHz counterpart was detected (morph_type = 'N').


Catalog Bibcode

2007ApJS..171...61H

References

CRATES: An all-Sky Survey of Flat-Spectrum Radio Sources
    Healey, S.E., Romani, R.W., Taylor, G.B., Sadler, E.M., Ricci, R.,
    Murphy, T., Ulvestad, J.S., Winn, J.N.
   <Astrophys. J. Suppl., 171, 61-71 (2007)>
   =2007ApJS..171...61H

Provenance

This table was created by the HEASARC in August 2007 based on the electronic version of Table 5 obtained from the electronic ApJ web site.

HEASARC Implementation

Many 4.8-GHz sources have multiple (2 - 20) 8.4-GHz counterparts, and these latter are all listed separately, hence there are 14,467 entries for the 11,131 4.8-GHz sources. The HEASARC has created a parameter called ctrpart_3p6_cm which is set to 1 for the brightest (or only) 8.4-GHz counterpart, to 2 for the second brightest, and so on. For the 762 entries for which no 8.4-GHz counterparts to the 4.8-GHz radio sources were found, this parameter has been set to 0.

The names of sources in this catalog are based on their 4.8-GHz positions, which are rendered in the table in the original reference as, for example, 'J000000-002157'. In the absence of a naming convention registered with or recommended by the CDS Dictionary of Nomenclature of Celestial Objects, the HEASARC has prepended 'CRATES ' to these original names, e.g., 'CRATES J000000-002157'.

There are 762 4.8-GHz sources for which no 8.4-GHz counterpart was detected, and hence for such sources no information was provided in the original version of this table in the reference paper except for the 4.8-GHz name/position and flux, and the 4.8-GHz to low-frequency spectral index (spectral_index_1): in order that users may locate this sources in coordinate-based searches, and given that the RA and Declination in this table is that of the 8.4-GHz source, the HEASARC has placed these sources at the positions implied by their (4.8-GHz-based) name, e.g., the source 'CRATES J000048+121810' has been assigned a J2000.0 RA and Declination of 00 00 48, +12 18 10.


Parameters

Name
The names of sources in this catalog are based on their J2000.0 4.8-GHz positions from the S5 Catalog (Kuhr et al. 1981, AJ, 86, 854), the GB6 Catalog (Gregory et al. 1996, ApJS, 103, 427,) or the PMN Catalog (Griffith and Wright 1993, AJ, 105, 1666, et seq.), which were rendered in the table in the original reference as, for example, 'J000000-002157'. In the absence of a naming convention registered with or recommended by the CDS Dictionary of Nomenclature of Celestial Objects, the HEASARC has prepended 'CRATES ' to these original names, e.g., 'CRATES J000000-002157' as an unofficial designation.

Ctrpart_3p6_cm
Many 4.8-GHz sources have multiple (2 - 20) 8.4-GHz counterparts, and these latter are all listed separately, hence there are 14,467 entries for the 11,131 4.8-GHz sources. The HEASARC has created this parameter to explicitly identify this feature of the table: its value is set to 1 for the brightest (or only) 8.4-GHz counterpart, to 2 for the second brightest, etc., etc. For the 762 entries for which no 8.4-GHz counterparts to the 4.8-GHz radio sources were found, this parameter has been set to 0. A combination of name and ctrpart_3p6_cm provides a unique identification for an 8.4-GHz radio source in this table.

Flux_6_cm
The 4.8-GHz flux density of the radio source, in mJy, for which an 8.4-GHz counterpart was sought. The 4.8-GHz flux densities come from the S5 Catalog (Kuhr et al. 1981, AJ, 86, 854), the GB6 Catalog (Gregory et al. 1996, ApJS, 103, 427,) or the PMN Catalog (Griffith and Wright 1993, AJ, 105, 1666, et seq.).

Spectral_Index_1
The spectral index, alpha, of the radio source between the low frequency (843 MHz for the sources from SUMSS (Mauch et al. 2003, MNRAS, 342, 1117, and 1400 MHz for the sources from NVSS (Condon et al. 1998, AJ, 115, 1693)) and 4.8 GHz, where the flux density at the frequency nu is S_nu ~ nu^alpha.

RA
The Right Ascension of the 8.4-GHz counterpart to the 4.8-GHz source in the selected equinox, except for cases for which no 8.4-GHz counterpart was detected (morph_type = 'N'), in which case it is the Right Ascension of the 4.8-GHz radio source in the selected equinox. The 8.4-GHz RAs were given in J2000.0 coordinates to a precision of 0.01 seconds of time in the original table, whereas the 4.8-GHz RAs were given in J2000.0 coodinates to a precision of only 1 second of time (although in the original catalogs from which the 4.8-GHz positions were taken, they were given with more precision).

Dec
The Declination of the 8.4-GHz counterpart to the 4.8-GHz source in the selected equinox, except for cases for which no 8.4-GHz counterpart was detected (morph_type = 'N'), in which case it is the Declination of the 4.8-GHz radio source in the selected equinox. The 8.4-GHz Declinations were given in J2000.0 coordinates to a precision of 0.1 arcseconds in the original table, whereas the 4.8-GHz Declinations were given in J2000.0 coodinates to a precision of only 1 arcsecond (although in the original catalogs from which the 4.8-GHz positions were taken, they were given with more precision).

LII
The Galactic Longitude of the radio source.

BII
The Galactic Latitude of the radio source.

Ref_RA_Dec
This parameter is a reference flag which indicates the origin of the 8.4-GHz position: 'V' for a a VLA source, 'A' for an ATCA source, and 'X' for a source from VLA program AP0282. Positions for the 139 sources from the latter were affected by some instrumental issues and as many as ~10 of these 'X' positions may be erroneous, as discussed in Section 3.2 of the reference paper.

Flux_3p6_cm
The 8.4-GHz flux density of the counterpart to the 4.8-GHz radio source, in mJy.

RA_J2000_Low_Freq
The J2000.0 Right Ascension of the low-frequency (843 MHz for the sources from SUMSS (Mauch et al. 2003, MNRAS, 342, 1117, 1400 MHz for the sources from NVSS (Condon et al. 1998, AJ, 115, 1693)) counterpart to the 4.8-GHz radio source.

Dec_J2000_Low_Freq
The J2000.0 Declination of the low-frequency (843 MHz for the sources from SUMSS (Mauch et al. 2003, MNRAS, 342, 1117, 1400 MHz for the sources from NVSS (Condon et al. 1998, AJ, 115, 1693)) counterpart to the 4.8-GHz radio source.

Flux_Low_Freq
The flux density, in mJy, of the low-frequency (843 MHz for the sources from SUMSS (Mauch et al. 2003, MNRAS, 342, 1117, 1400 MHz for the sources from NVSS (Condon et al. 1998, AJ, 115, 1693)) counterpart to the 4.8-GHz radio source.

Spectral_Index_2
The spectral index, alpha, of the radio source between the low frequency (843 MHz for the sources from SUMSS (Mauch et al. 2003, MNRAS, 342, 1117, and 1400 MHz for the sources from NVSS (Condon et al. 1998, AJ, 115, 1693)) and 8.4 GHz, where the flux density at the frequency nu is S_nu ~ nu^alpha.

Morph_Type
This flag parameter indicates the morphological classification of the 8.4-GHz radio source, or the lack of a detection, as follows (see Sction 5.2 of the reference paper for a more complete description):

      N = No detection
      P = point source
      S = short jet (<= 1" for VLA maps)
      L = long jet (> 1")
      D = double (component flux ratio <= 2)
      C = complex morphology
  

Contact Person

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

Page Author: Browse Software Development Team
Last Modified: 23-Apr-2008