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VLAGBSPER - VLA Gould's Belt Survey Perseus Region Source Catalog

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Overview

This table contains a source catalog from multi-epoch, large-scale (~2,000 arcmin2), fairly deep (~16 microJansky or uJy), high-resolution (~1") radio observations of the Perseus star-forming complex that were obtained with the Karl G. Jansky Very Large Array (VLA) at frequencies of 4.5 and 7.5 GHz. These observations were mainly focused on the clouds NGC 1333 and IC 348, although the authors also observed several fields in other parts of the Perseus complex. They detect a total of 206 sources, 42 of which are associated with young stellar objects (YSOs). The radio properties of about 60% of the YSOs are compatible with a non-thermal radio emission origin. Based on their sample, the authors find a fairly clear relation between the prevalence of non-thermal radio emission and the evolutionary status of the YSOs. By comparing their results with previously reported X-ray observations, they show that YSOs in Perseus follow a Gudel-Benz relation with a value of the kappa parameter (LX/Lrad = kappa x 10(15.5 +/- 1) [Hz]) of 0.03, consistent with other regions of star formation. The authors argue that most of the sources detected in their observations that are not associated with known YSOs are extragalactic, but provide a list in the reference paper Of 20 unidentified radio sources whose radio properties are consistent with them being YSO candidates. Finally, they also detect five sources with extended emission features that can clearly be associated with radio galaxies.

The observations were collected with the VLA of the National Radio Astronomy Observatory in B and BnA configurations. Two frequency sub-bands, each 1 GHz wide and centered at 4.5 and 7.5 GHz, respectively, were recorded simultaneously. The observations were obtained in three observing sessions, on 2011 March 06/13, April 14/25, and May 01/02/10/19/22, typically separated from one another by a month. This dual-frequency, multi-epoch strategy was chosen to enable the characterization of the spectral index and variability of the detected sources, as well as to help with the identification of the emission mechanisms.

The locations of the VLA observations are shown in Figure 1 of the reference paper. Other details of the observations are given in Table 1 of the reference paper. The approximate positions of the two main fields observed are:

     RA   (ICRS)    DE        Designation(s)
03 28 55 +31 22.2 Ced 16 = NGC 1333 03 44 34 +32 09.8 NAME omi Per Cloud = IC 348
This HEASARC table contains the contents of Table 2 (74 radio sources
detected in NGC 1333), Table 3 (91 radio sources detected in IC 348) and
Table 4 (41 radio sources detected in single fields in Perseus) from the
reference paper, totaling 206 radio sources.


Catalog Bibcode

2016ApJ...818..116P

References

The Gould's Belt very large array survey.
V. The Perseus region.
    Pech G., Loinard L., Dzib S.A., Mioduszewski A.J., Rodriguez L.F.,
    Ortiz-Leon G.N., Rivera J.L., Torres R.M., Boden A.F., Hartman L.,
    Kounkel M.A., Evans Ii N.J., Briceno C., Tobin J., Zapata L.A.
   <Astrophys. J., 818, 116 (2016)>
   =2016ApJ...818..116P    (SIMBAD/NED BibCode)

Provenance

This table was created by the HEASARC in February 2018 based on an ASCII version of Table 2 from the reference paper that was obtained from the ApJ website and on the CDS catalog J/ApJ/818/116 files table3.dat and table4.dat that contains Tables 3 and 4 from the reference paper.

Parameters

Region_Code
This HEASARC-created parameter indicates the location of the detected radio source. If from Table 2 of the reference paper that lists 74 radio sources detected in NGC 1333, it is set to 'N', if from Table 3 that lists 91 radio sources detected in IC 348, it is set to 'I', and if from Table 4 that lists 41 radio sources detected in single fields in Perseus, it is set to 'S'.

Name
The radio source J2000.0 position-based designation, viz., 'GBS-VLA JHHMMSS.ss+DDMMSS.s', where the prefix reflects the fact that these sources were found as part of the Gould's Belt Very Large Array Survey.

RA
The Right Ascension of the radio source in the selected equinox. This was not given explicitly in the original table but was constructed by the HEASARC from the J2000.0 position-based source designation which was given to a precision of 0.01 seconds of time.

Dec
The Declination of the radio source in the selected equinox. This was not given explicitly in the original table but was constructed by the HEASARC from the J2000.0 position-based source designation which was given to a precision of 0.1 arcseconds.

LII
The Galactic Longitude of the radio source.

BII
The Galactic Latitude of the radio source.

New_Source_Flag
This parameter contains a flag indicating whether or not the radio source is a 'new' detection, as follows:

      Y = Source without reported counterparts at any frequency;
      N = Source with known counterpart.
  

Flux_4p5_GHz
The 4.5-GHz flux density of the radio source, in mJy. The flux densities are measured in the combined epoch images.

Flux_4p5_GHz_Error
The uncertainty in the 4.5-GHz flux density of the radio source, in mJy. The quoted flux errors comprise the statistical noise in the image, the 5% systematic uncertainty resulting from possible errors in the flux calibration, and the uncertainty induced by the absolute pointing error of the primary beam of the VLA antennas, added in quadrature.

Var_4p5_GHz_Limit
This limit parameter is set to '>' if the corresponding flux density variability percentage is a lower limit rather than an actual value.

Var_4p5_GHz
The variability of the source flux density at 4.5 GHz, in percent. Once the sources were identified in the concatenated images, the authors visually searched for them in the images of the individual epochs. An estimate of the level of variability of the sources was measured by comparing the fluxes measured at the three epochs. Specifically, the authors calculated, for each source, the difference between the highest and lowest measured fluxes and normalized it by the maximum flux. They did not search for variability sources with extended emission because sensitivity and UV coverage effects can produce spurious variation. The authors consider a source to be highly variable if its variability at any frequency is >= 50% at a 3-sigma level.

Var_4p5_GHz_Error
The uncertainty in the variability of the source flux density at 4.5 GHz, in percent.

Var_4p5_GHz_Flag
This flag parameter contains the following two non-blank coded values concerning the variability of the source flux density at 4.5 GHz:

      A = Source not detected at three times the noise level in individual
          epochs, but detected in the image of the concatenated epochs;
      E = Extended, and therefore not studied for variability.
  

Flux_7p5_GHz_Limit
This limit parameter is set to '<' if the corresponding flux density is an upper limit rather than an actual value.

Flux_7p5_GHz
The 7.5-GHz flux density of the radio source, in mJy. The flux densities are measured in the combined epoch images.

Flux_7p5_GHz_Error
The uncertainty in the 7.5-GHz flux density of the radio source, in mJy. The quoted flux errors comprise the statistical noise in the image, the 5% systematic uncertainty resulting from possible errors in the flux calibration, and the uncertainty induced by the absolute pointing error of the primary beam of the VLA antennas, added in quadrature.

Var_7p5_GHz_Limit
This limit parameter is set to '>' if the corresponding flux density variability percentage is a lower limit rather than an actual value.

Var_7p5_GHz
The variability of the source flux density at 7.5 GHz, in percent. Once the sources were identified in the concatenated images, the authors visually searched for them in the images of the individual epochs. An estimate of the level of variability of the sources was measured by comparing the fluxes measured at the three epochs. Specifically, the authors calculated, for each source, the difference between the highest and lowest measured fluxes and normalized it by the maximum flux. They did not search for variability sources with extended emission because sensitivity and UV coverage effects can produce spurious variation. The authors consider a source to be highly variable if its variability at any frequency is >= 50% at a 3-sigma level.

Var_7p5_GHz_Error
The uncertainty in the variability of the source flux density at 7.5 GHz, in percent.

Var_7p5_GHz_Flag
This flag parameter contains the following two non-blank coded values concerning the variability of the source flux density at 7.5 GHz:

      A = Source not detected at three times the noise level in individual
          epochs, but detected in the image of the concatenated epochs;
      E = Extended, and therefore not studied for variability.
  

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

Spectral_Index
The radio spectral index, alpha, where the flux density as a function of frequency, nu, S_nu_~ nualpha, from the flux densities measured in each sub-band (at 4.5 and 7.5 GHz).

Spectral_Index_Error
The uncertainty in the radio spectral index, alpha. To calculate the errors on the spectral indices, the three sources of errors in the flux at each frequency were added in quadrature, and the final error was obtained using standard error propagation theory. The authors are aware that this procedure to obtain errors on the spectral indices is a little conservative given that the two frequencies were recorded simultaneously, making the ratio of the two bands independent of the absolute flux uncertainty, but they prefer to maintain it to make sure they do not underestimate the errors.


Contact Person

Questions regarding the VLAGBSPER database table can be addressed to the HEASARC User Hotline.
Page Author: Browse Software Development Team
Last Modified: Thursday, 15-Feb-2018 12:35:38 EST