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GP7C151MHZ - 7C(G) 151-MHz Northern Galactic Plane Survey Catalog

HEASARC
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Overview

Results from a survey of the northern Galactic plane (at Declination >= 30o at 151 MHz made with the Cambridge Low Frequency Synthesis Telescope (CLFST) are presented in this table. This survey was designated the 7C(G) - i.e. the Galactic portion of the then-ongoing 7C surveys. The 7C(G) covers the regions 80o < l < 104o and 126o < l < 180o, for |b| <= 5.5o, and has some coverage to |b| ~ 9o, with a resolution of ~70 x70 cosec{delta} arcsec2 (RA x Dec). The observations, data reduction and calibration of this survey are described in the reference paper, and the catalog of 6262 compact sources, with a completeness limit of ~ 0.25 Jy (250 mJy) over most of the survey region, is presented in this table. The catalog has an rms positional accuracy of better than 10 arcseconds, and the flux densities are tied to the scale of Roger, Bridle & Costain (1973, AJ, 78, 1030) with an accuracy of better than 10 per cent.

Catalog Bibcode

1998MNRAS.294..607V

References

The 7C(G) survey of radio sources at 151MHz - the Galactic plane at
80deg<l<104deg and 126deg<l<180deg, for |b|<5.5deg.
       Vessey S.J., Green D.A.
      <Mon. Not. R. Astron. Soc. 294, 607 (1998)>
      =1998MNRAS.294..607V

Provenance

This table was created by the HEASARC in October 2010 based on CDS table J/MNRAS/294/607 file 7cg.dat.

Parameters

Name
The source designation adopted by the HEASARC, viz., '7C HHMMSS.s+DDMMSS', where the numerical part of the name is the B1950.0 beam-fitted position of the radio source. The CDS Dictionary of Nomenclature of Celestial Objects recommends a truncated version of this naming convention, viz., either '7C HHMM+DDMMa' or '7C(G) HHMM+DDMMa', but the HEASARC has adopted the higher precision position-based naming convention that is now recommended for the main 7C catalog.

RA
The Right Ascension of the beam-fitted position of the radio source in the selected equinox. This was given in B1950.0 equatorial coordinates in the original table to a precision of 0.1 seconds of time. The rms accuracy of the RA is 5 arcseconds.

Dec
The Declination of the beam-fitted position of the radio source in the selected equinox. This was given in B1950.0 equatorial coordinates in the original table to a precision of 1 arcsecond. The rms accuracy of the Dec is 7 arcseconds.

LII
The Galactic Longitude of the beam-fitted position of the radio source.

BII
The Galactic Latitude of the beam-fitted position of the radio source.

Centroid_RA
The Right Ascension of the centroid position of the radio source in the selected equinox. This was given in B1950.0 equatorial coordinates in the original table to a precision of 0.1 seconds of time. Multiple peaks which have been integrated together have the same centroid position.

Centroid_Dec
The Declination of the centroid position of the radio source in the selected equinox. This was given in B1950.0 equatorial coordinates in the original table to a precision of 1 arcsecond. Multiple peaks which have been integrated together have the same centroid position.

Flux_151_MHz
The beam-fitted flux density Sbf of the radio source at 151 MHz, in mJy/beam (converted by the HEASARC from the Jy/beam units used in the original table). The beam-fitted flux density is the preferred flux density unless the source is clearly extended, in which case the integrated flux density should be used.

Int_Flux_151_MHz
The integrated flux density Sin of the radio source at 151 MHz, in mJy (converted by the HEASARC from the Jy units used in the original table). The beam-fitted flux density is the preferred flux density unless the source is clearly extended, in which case the integrated flux density should be used.

SNR
The signal-to-noise ratio (S/N) of the radio source as defined by Waldram and Riley (1993, MNRAS, 265, 853), i.e., the interpolated peak height of the source on the map (after subtraction of the local zero level), divided by the local noise.

Source_Extent
The extent of the source size in units of the local beam area. This estimate is influenced by residual ionospheric smearing of the synthesized beam. Another measure of whether a source is resolved or not is the ratio of the integrated to beam-fitted flux densities, Sin/Sbf. The flux density calibration is performed in such a way as to ensure that the median value of this ratio for unresolved sources is unity. Thus, any source with this ratio >> 1 is resolved, and, for this survey, a ratio of Sin/Sbf >= 1.2 is a good indication that the source is resolved.

Num_Local_Max
The number of individual peaks that were included in the flux integration. (See also the source_flag parameter, a single character flag indicating whether the source is the main ('M') or a component ('C') peak in the integration). If no number and source_flag values are given then the source has a single peak only. For multiple sources, each peak has a separate entry in this source list, with its own beam-fitted flux density and position, although the integrated flux and the centroid position are the same for each entry. As noted in the reference paper, some multiple peaked sources appear with different numbers of components in overlapping fields. These entries have not been averaged together, and care should be taken with such entries.

Source_Flag
This parameter contains a single character flag indicating whether the source is the main ('M') or a component ('C') peak in the integration.


Contact Person

Questions regarding the GP7C151MHZ database table can be addressed to the HEASARC User Hotline.

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