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 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:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 111 281 Sources from 1LC 20 centimeter Survey
table4.dat 83 26 Sources from 1LC 6 centimeter Survey
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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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)
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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
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Byte-by-byte Description of file: table4.dat
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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)
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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
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Acknowledgements: From ApJS electronic version
(End) James Marcout, Patricia Bauer [CDS] 09-Nov-1998