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J/ApJS/118/201          Galactic Center 6 and 20cm survey      (Lazio+, 1998)
Hyperstrong radio-wave scattering in the Galactic Center.
I. A survey for extragalactic sources seen through the Galactic Center.
       Lazio T.J.W., Cordes J.M.
      <Astrophys. J. Suppl. Ser. 118, 201 (1998)>
      =1998ApJS..118..201L
ADC_Keywords: Radio sources ; Radio continuum

Keywords: Galaxy: center - ISM: general - quasar: general -
          radio continuum: ISM - scattering - surveys

Description:
    We have used  the VLA to survey  10 fields at 20  cm (1658MHz)  and 11
    fields at 6 cm (5GHz)  that are between 7'  and 137'  from SgrA*.  Our
    objective was to identify  extragalactic  sources  and  measure  their
    scattering diameters so  as  to  constrain  the  GC-scattering  region
    separation.  In  order to find  sources within these  fields,  we have
    employed  pdfCLEAN,  a source detection algorithm in which sources are
    identified in an  image by  comparing the  intensity histogram  of the
    image to that expected  from a  noise-only image.   We found  over 100
    sources,   with the faintest  sources being approximately  3 mJy.  The
    average number of sources per field is approximately 10, though fields
    close to SgrA* tend to contain fewer sources.

    A  number of Galactic sources are included in our source catalog.  The
    double-lobed source 1LC 359.872+0.178,   potentially  an  X-ray  quiet
    version of 1E 1740.7-2942, a shell-like structure with a central point
    source, and a possible radio transient, are discussed in the paper.

File Summary:

       FileName      Lrecl  Records   Explanations

ReadMe            80        .   This file
table3.dat       111      281   Sources from 1LC 20 centimeter Survey
table4.dat        83       26   Sources from 1LC  6 centimeter Survey


Byte-by-byte Description of file: table3.dat

   Bytes Format Units   Label     Explanations

   1- 13  A13   ---     1LC       Source designation
      14  A1    ---     n_1LC     [em] Note on 1LC (1)
  16- 17  I2    h       RAh       Right ascension (J2000.0)
  19- 20  I2    min     RAm       Right ascension (J2000.0)
  22- 27  F6.3  s       RAs       Right ascension (J2000.0)
      29  A1    ---     DE-       Declination sign (J2000.0)
  30- 31  I2    deg     DEd       Declination (J2000.0)
  33- 34  I2    arcmin  DEm       Declination (J2000.0)
  36- 40  F5.2  arcsec  DEs       Declination (J2000.0)
  42- 47  F6.1  mJy     I1658MHz  ? Peak intensity at 1658MHz in mJy/beam,
                                     with a 5" beam
  49- 54  F6.1  mJy     S1658MHz  ? Integrated flux at 1658MHz
  56- 59  F4.1  arcsec si1658MHz  ? Apparent size at 1658MHz
  61- 66  F6.1  mJy     I1281MHz  ? Peak intensity at 1281MHz in mJy/beam,
                                     with a 5" beam
  68- 73  F6.1  mJy     S1281MHz  ? Integrated flux at 1281MHz
  75- 79  F5.1  arcsec si1281MHz  ? Apparent size at 1281MHz
  81- 85  F5.1  ---     SI        ? Spectral index between 1281 and 1658MHz (2)
  87- 90  F4.1  arcmin  Offset    Offset from phase center
  92-111  A20   ---     Notes     Notes (3)

Note (1): e: extended source
          m: the source is one of multiple components
Note (2): Extreme values probably reflect the closely spaced observing
           frequences
Note (3): GPSR: the source has a counterpart in the Columbia Galactic Plane
                  Survey
           1LC: a source is also detected in our 6cm survey
           VLA: VLA calibrators
           Gal: source likely to be Galactic
          xgal: source likely to be extragalactic


Byte-by-byte Description of file: table4.dat

   Bytes Format Units   Label     Explanations

   1- 13  A13   ---     1LC       Source designation
      14  A1    ---     n_1LC     [em] Note on 1LC (1)
  16- 17  I2    h       RAh       Right ascension (J2000.0)
  19- 20  I2    min     RAm       Right ascension (J2000.0)
  22- 27  F6.3  s       RAs       Right ascension (J2000.0)
      29  A1    ---     DE-       Declination sign (J2000.0)
  30- 31  I2    deg     DEd       Declination (J2000.0)
  33- 34  I2    arcmin  DEm       Declination (J2000.0)
  36- 40  F5.2  arcsec  DEs       Declination (J2000.0)
  42- 46  F5.1  mJy     I6cm      ? Peak intensity at 6cm in mJy/beam,
                                     with a 1.8" beam
  48- 53  F6.1  mJy     S6cm      ? Integrated flux at 6cm
  55- 58  F4.1  arcsec  si6cm     ? Apparent size at 6cm
  60- 63  F4.1  ---     SI        ? Spectral index between 6 and 20cm (2)
  65- 67  F3.1  arcmin  Offset    Offset from phase center
  69- 83  A15   ---     Notes     Notes (3)

Note (1): e: extended source
          m: the source is one of multiple components
Note (2): Extreme values probably reflect the closely spaced observing
           frequences
Note (3): GPSR: the source has a counterpart in the Columbia Galactic Plane
                  Survey
           1LC: a source is also detected in our 6cm survey
           VLA: VLA calibrators
           Gal: source likely to be Galactic
          xgal: source likely to be extragalactic


Acknowledgements: From ApJS electronic version

(End)                          James Marcout,  Patricia Bauer [CDS]  09-Nov-1998