VIII/72 CLASS survey of radio sources (Myers+, 2003)
The Cosmic Lens All Sky Survey.
I. Source selection and observations.
Myers S.T., Jackson N.J., Browne I.W.A., de Bruyn A.G., Pearson T.J.,
Readhead A.C.S., Wilkinson P.N., Biggs A.D., Blandford R.D., Fassnacht C.D.,
Koopmans L.V.E., Marlow D.R., McKean J.P., Norbury M.A., Phillips P.M.,
Rusin D., Shepherd M.C., Sykes C.M.
<Mon. Not. R. Astron. Soc. 341, 1 (2003)>
=2003MNRAS.341....1M 2003MNRAS.341....1M
II. Gravitational lens candidate selection and follow-up.
<Mon. Not. R. Astron. Soc. 341, 13 (2003)>
=2003MNRAS.341...13B 2003MNRAS.341...13B
ADC_Keywords: Radio sources
Keywords: cosmology ; gravitational lensing
Abstract:
The Cosmic Lens All-Sky Survey (CLASS) is an international
collaborative program aimed at obtaining high-resolution radio images
of over 10000 flat-spectrum radio sources in order to create the
largest and best studied statistical sample of radio-loud
gravitationally lensed systems. CLASS is aimed at identifying lenses
where multiple images are formed from compact flat-spectrum radio
sources, which should be easily identifiable in the radio maps (Browne
et al., 2003MNRAS.341...13B 2003MNRAS.341...13B). In four observing ``seasons'' from
1994-1999, CLASS has observed 13832 radio sources. When combined with
the JVAS survey, the CLASS sample contains over 16,000 images. Using
the GB6 and NVSS surveys, a complete statistical subset of 11685
sources has been constructed. These were selected from the NVSS 20-cm
(Condon et al., 1998, Cat. VIII/65) and GB6 6-cm (Gregory et al.,
1996, Cat. VIII/40) catalogues by the selection criteria:
declination >0deg, |b|<10deg, S(6cm)≥30mJy, and spectral index
between 6 and 20cm flatter than -0.5 (S proportional to
frequency+alpha). The remaining sources were selected using earlier
versions of these catalogues or with slightly relaxed versions of
these criteria.
Introduction:
The data in this table were assembled from pointings at 16503 radio
sources in the JVAS and CLASS surveys between 1990 and 1999 using the
VLA in A-configuration at 8.4GHz. The resolution is approximately
220 milliarcsec. The data were mapped using an automatic DIFMAP script
(Shepherd et al., 1997, ASP Conference Series, 125, 77) which located
the brightest radio source within a 2' by 2' box around the pointing
position, and searched for all subsidiary components within a 70"x70"
box around the brightest source. Sources were regarded as not detected
if no component of 5mJy or more was visible in the initial search box.
Except in cases of bad data or complicated sources, the positions of
primary sources of 30mJy or above are accurate to about 40mas. More
details of the process are given in the paper (2003MNRAS.341....1M 2003MNRAS.341....1M)
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
catalog.dat 129 23418 CLASS catalog
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See also:
VIII/65 : 1.4GHz NRAO VLA Sky Survey (NVSS) (Condon+ 1998)
VIII/40 : GB6 catalog of radio sources (Gregory+ 1996)
http://www.jb.man.ac.uk/research/gravlens/ : Paper HomePage
Byte-by-byte Description of file: catalog.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- --- [GB6J]
5- 17 A13 --- GB6 Name from the Greenbank 6-cm catalogue
Gregory et al., 1996, Cat. VIII/40
19- 26 A8 --- Obsname Name in the VLA observation list
28- 31 F4.2 --- qin ? Quality indicator of map (1)
33- 34 I2 h RAph ? Pointing position Right Ascension J2000
36- 37 I2 min RApm ? Pointing position Right Ascension J2000
39- 43 F5.2 s RAps ? Pointing position Right Ascension J2000
46 A1 --- DEp- ? Pointing position Declination sign
47- 48 I2 deg DEpd ? Pointing position Declination J2000
50- 51 I2 arcmin DEpm ? Pointing position Declination J2000
53- 56 F4.1 arcsec DEps ? Pointing position Declination J2000
61- 71 A11 --- dir Data directory of observing epoch (2)
75- 76 I2 h RAh ? Component position Right Ascension J2000 (3)
78- 79 I2 min RAm ? Component position Right Ascension J2000 (3)
81- 87 F7.4 s RAs ? Component position Right Ascension J2000 (3)
90 A1 --- DE- ? Component position Declination sign (3)
91- 92 I2 deg DEd ? Component position Declination J2000 (3)
94- 95 I2 arcmin DEm ? Component position Declination J2000 (3)
97-102 F6.3 arcsec DEs ? Component position Declination J2000 (3)
104-112 F9.1 mJy S8.4GHz ? 8.4GHz flux density of component (3)
114-119 I6 mas maj ? Fitted major axis of component (3)
121-124 F4.2 --- b/a [0,1]? Fitted axis ratio of resolved
components (3) (4)
126-129 I4 deg PA [-90/90]? Position angle fitted to
component (3)
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Note (1): This is defined as the ratio of the flux density of the
brightest component in the radio map, divided by the initial peak in
the residual map before self-calibration. It serves as a rough quality
control, as the data were processed using an automatic DIFMAP script
without human intervention. In an ideal case the ratio should be 1. In
cases where the number is 1.5 or greater, the map may contain spurious
radio structure and the original data should be consulted. A blank field
indicates a non-detection
Note (2): Observing epoch:
90-92 = JVAS
94 = CLASS1
95 = CLASS2
98 = CLASS3
99 = CLASS4
Note (3): These data are repeated for each radio component detected
in an observation.
Note (4): This is produced by the DIFMAP modelfit software.
In cases where the component is not significantly resolved the axis
ratio is set to 0.00.
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(End) Neal Jackson [Jodrell Bank Obs.] 10-Feb-2003