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VLAM31325M - VLA M 31 325-MHz Source Catalog

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Overview

This table contains some of the results from a 325-MHz radio survey of M 31, conducted with the A configuration of the Very Large Array. The survey covered an area of 7.6 square degrees, and a total of 405 radio sources between <~ 6" and 170" in extent were mapped with a resolution of 6" and a 1-sigma sensitivity of ~ 0.6mJy/beam. For each source, its morphological class, major axis thetaM, minor axis thetam, position angle thetaPA, peak flux I, integrated flux density S, spectral index alpha, and spectral curvature parameter {phi were calculated. A comparison of the flux and radial distribution - both in the plane of the sky and in the plane of M 31 - of these sources with those of the XMM-Newton Large-Scale Structure Survey and the Westerbork Northern Sky Survey revealed that a vast majority of sources detected are background radio galaxies. As a result of this analysis, the authors expect that only a few sources are intrinsic to M 31.

This study is based on a 5 hr (4 hr on-source) observation of M 31 conducted on 2000 December 15 with the VLA in A configuration. The procedures used to generate the source list and the source properties (essentially making use of the MIRIAD task SFIND) are discussed in Sections 2.2.2 and 2.3 of the reference paper, respectively.

Catalog Bibcode

2004ApJS..155...89G

References

A wide-field, low-frequency radio survey of the field of M31.
I. Construction and statistical analysis of the source catalog.
    Gelfand J.D., Lazio T.J.W., Gaensler B.M.
   <Astrophys. J. Suppl. Ser., 155, 89-100 (2004)>
   =2004ApJS..155...89G

Provenance

This table was created by the HEASARC in September 2014 based on CDS Catalog J/ApJS/155/89 file table3.dat, the GLG (Gelfand, Lazio, Gaensler) source list.

Parameters

Source_Number
A unique source number for each source in this catalog, ordered in increasing distance from the center of the FOV.

Name
The name of the source, using the GLG prefix (Gelfand, Lazio, Gaensler) and the source number. The sources are ordered in increasing distance from the center of the FOV.

Source_Type
The type of source. This is the morphological category of the sources as defined in Section 2.3 of the reference paper, defined as follows: 

      U   = unresolved;
      El  = elongated;
      C   = complex;
      Ex  = extended;
      ExG = Extended source with a counterpart in one or more other radio
            surveys of M31.

RA
The Right Ascension of the radio source in the selected equinox. This was given in J2000.0 coordinates to a precision of 0.01 seconds of time in the original table.

RA_Error
The error in the Right Ascension of the radio source, in arcseconds.

Dec
The Declination of the radio source in the selected equinox. This was given in J2000.0 coordinates to a precision of 0.01 arcseconds in the original table.

Dec_Error
The error in the declination of the radio source, in arcseconds.

LII
The Galactic Longitude of the radio source.

BII
The Galactic Latitude of the radio source.

Angular_Radius
The angular distance of the radio source from the center of M 31, in arcminutes.

Projected_Radius
The projected radius of of the radio source from the center of M 31, in kpc, where a distance to M 31 of 780 kpc, an angle of the optical disk of M 31 relative to north on the sky of 52 degrees, and an inclination of the plane of M 31 to the plane of the sky of 77 degrees have been assumed. See Section 4.1 of the reference paper for fuller details.

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

Major_Axis_Error
The error in the major axis of the radio source, sigma(thetaM), in arcseconds. After the primary beam correction was applied, this error was calculated using equation (29a) in Condon et al. (1998, AJ, 115, 1693). In this calculation, the authors assumed that the signal-to-noise of a source was equal to the ratio of the integrated flux density of the source to the rms of the flux density around the source, i.e., S/sigmarms.

Minor_Axis
The minor axis of the radio source, thetam, in arcseconds.

Minor_Axis_Error
The error in the minor axis of the radio source, sigma(thetam), in arcseconds. After the primary beam correction was applied, this error was calculated using equation (29b) in Condon et al. (1998, AJ, 115, 1693). In this calculation, the authors assumed that the signal-to-noise of a source was equal to the ratio of the integrated flux density of the source to the rms of the flux density around the source, i.e., S/sigmarms.

Position_Angle
The position angle of the major axis of the radio source, PA, measured eastwards from north, in degrees.

Position_Angle_Error
The error in the position angle of the major axis of the radio source measured eastwards from north, in degrees. After the primary beam correction was applied, this error was calculated using equation (30) in Condon et al. (1998, AJ, 115, 1693). In this calculation, the authors assumed that the signal-to-noise of a source was equal to the ratio of the integrated flux density of the source to the rms of the flux density around the source, i.e., S/sigmarms.

Flux_325_MHz
The peak brightness, I, of the radio source at 325 MHz, in mJy/beam.

Flux_325_MHz_Error
The error in the peak brightness, I, of the radio source at 325 MHz, in mJy/beam. This is calculated as specified in Section 2.3 of the reference paper.

Int_Flux_325_MHz
The integrated flux density, S, of the radio source at 325 MHz, in mJy.

Int_Flux_325_MHz_Error
The error in the integrated flux density, S, of the radio source at 325 MHz, in mJy. This is calculated as specified in Section 2.3 of the reference paper.

RMS_325_MHz
The root mean square, sigmarms, of the flux density around the radio source, in mJy.

Spectral_Index_Limit
This limit parameter is set to '<=' if the corresponding value of the spectral index is an upper limit.

Spectral_Index
The radio spectral index, alpha, of the source, as calculated in Section 4.3 of the reference paper. The spectral indices of 'Ex'-type sources without a counterpart in another radio survey were not published because they are most likely spurious, as mentioned in Section 2.3 of the reference paper. It is also possible that some of the steeper spectrum 'U'-type sources (alpha < 2) are spurious as well.

Spectral_Index_Error
The error in the the radio spectral index, alpha, of the source.

Spectral_Curvature
The radio spectral curvature parameter, phi, of the source, as calculated in Section 4.3 of the reference paper.

Spectral_Curvature_Error
The error in the radio spectral curvature parameter, phi, of the source,

Contact Person

Questions regarding the VLAM31325M database table can be addressed to the HEASARC Help Desk.
Page Author: Browse Software Development Team
Last Modified: Monday, 16-Sep-2024 17:36:25 EDT