A 5-GHz VLA survey

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1994ApJS...91..347Becker+

A 5-GHz VLA Survey of the Galactic Plane

Becker, R. H., White, R. L., Helfand, D. J., & Zoonematkermani, S. Helfand D.J., Zoonematkermani S., Becker R.H., White R.L.

Abstract:

We have used the VLA to survey the inner Galaxy (|b| < 0.4^o, l=350-40^o) at 5 GHz to a limiting sensitivity of between 2.5 and 10 mJy. The survey has resulted in a catalog of 1272 discrete sources (including 100 sources outside the formal survey area) of which we have tentetive identified ~ 450 as ultracompact HII regions and ~45 as planetery nebulae. Approximately 30 % of the radio sources are detected in the IRAS PSC. The results confirm a scale height of only 30 pc for ultracompact HII regions. We show that source lists generated from the IRAS PSC alone suffer serious selection effects; the combination of the IRAS and radio survey allows us to produce a much more complete census of the regions of massive star formation in our Galaxy.

Th maximize snsitivity over the primary beam field of view (10' FWHM), data were collected using two 25 MHz bandpasses centered close to 4.9 GHz. The angular resolution of the survey is ~4" except for fields observed in the CnD cofiguration, which had slightly worse resolution. The flux density scale was based on observations of the standard calibrator 3C286.

The construction of the catalog required procedures for the extraction of the 5GHz sources, for merging the 5GHz and 1.4 GHz survey information, and for associating the 5GHz sources with sources in the IRAS RSC and other existing catalogs. The 5GHz extraction was done visually aided by contour plots and interactive gray-scale displays. Sources brighter than 5 x rms were fitted with two-dimensional Gaussians. In addition, the positions of sources from the 1.4 GHz catalog were visually inspected in the 5 GHz images for detections down to the 3 x rms level.

References

Zoonematkermani S., Helfand D., Becker R.H., White R.L., Perley R.L. Astrophys. J. S.S., 74, 181 - 224. (1990) Paper I.
Becker R. H., White R. L., McLean B.J., Helfand D.J., & Zoonematkermani, S. 1990, Ap. J., 358, 485. Paper II.
White R. L., Becker R. H., & Helfand D.J. 1991, Ap. J. 371, 148. Paper III.
Helfand D.J., Zoonematkermani S., Becker R.H., White R.L. 1992, Ap. J. S., 80, 211. Paper IV.
Becker, R. H., White, R. L., Proctor D. 1992, A.J., 103, 544. Paper V.

Table 2 contains the complete list of VLA sources within the 5 GHz survey area from both the 5GHz and 1.4 GHz catalogs.

Keywords: HII regions-planetary nebulae: general-radio continuum: galaxies-
          -surveys
File Summary:
-----------------------------------------------------------------------
File Name    Lrecl  Records      Explanations
------------------------------------------------------------------------
ReadMe          80        .      this file
table1          97     1360      5-GHz source list for the galactic plane
------------------------------------------------------------------------
Byte-per-byte Description of file: table1
----------------------------------------------------------------------------
 Bytes  Format    Unit     Label   Explanation
---------------------------------------------------------------------------
 1- 13  A13      ---      NAM6    6cm-IAUname in format lll.lll+b.bbb
16- 17  I2       h        RAh     [0,24[ Right ascension (B1950) at 6cm
19- 20  I2       min      RAm     [0,60[ Right ascension (minutes)
22- 26  F5.2     s        RAs     [0,60[ Right ascension (seconds)
    28  A1       .        DE-     Declination sign (B1950)
29- 30  I2       deg      DEd     [0,90] Declination (B1950)(degrees) at 6cm
32- 33  I2       arcmin   DEm     [0,60[ Declination (minutes)
35- 38  F4.1     arcsec   DEs     [0,60[ Declination (seconds)
    40  A1       ---      ?????   [<]? upper limit sign
41- 45  F5.1     mJy      Spk6    peak 4885 MHz flux (1)
    47  A1       ---      ?????   [<]? upper limit sign
48- 53  F6.1     mJy      Sint    integrated 4885 MHz flux (1)
63- 67  F5.1     arcsec   dia6    [...]? source diameter at 6cm (2)
62- 74  A13      ---      NAM20   20cm-IAUname in format lll.lll+b.bbb
    75  A1       ---      cmp20   component suffix ??
76- 79  I4       mJy      Spk20   peak 1490 MHz flux (1)
80- 84  I5       mJy      Sint20  integrated 1490 MHz flux (1)
85- 90  F6.1     arcsec   dia20   [...]? source diameter at 20cm (2)
91- 99  A9       ---      NOTE    notes
-------------------------------------------------------------------------

Notes:

(1) The values of Speak and Sint have been corrected forr the loss of sensitivity of the primary beam of the antennas away from the field centre.
(2) The quoted diameters are the mean of the best-fit FWHM of the major and minor axes of the sources as determined by the Gaussian fits. Values of '0.0' were replaced by blank entries at CDS.

History:
The files were provided courtesy R.H. Becker to H. Andernach. It was numbered R106 in H.A.'s "List of Astronomical Catalogues and Documents not available from NASA-ADC but kindly provided on request by various authors".

Heinz Andernach [CDS] 07-Mar-1994 Sergei Trushkin [SAO] 29-Dec-1996

example:
------------------------ 6cm data ------------------------   --------- 20cm data ---------
6cm Name           RA   (1950)  Dec     Fpeak    Fint Size   20cm Name    Fpeak Fint  Size Cmts
----+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8----+----9----+
349.987-0.067  17 16 19.92 -37 18 45.9    5.7     9.0  2.4                   16
350.016+0.433  17 14 22.21 -37 00  0.5   90.1   108.9  1.9   350.015+0.433   33   42   2.6 I