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Catalogues from a Deep 327 MHz Westerbork Survey
We present the results of a deep survey of six fields with the Westerbork
Synthesis Radio Telescope at 327 MHz. The angular resolution of the WSRT
telescope is approximately 52"x52"*(csc DEC) at 327 MHz and 28"x28"*(csc DEC)
at 608 MHz, though the actual values vary slightly due to details of uv-
coverage. In total we have detected 4519 sources brighter than our 5-sigma
noise level, which ranges from 2.4-3.5 mJy/beam, over an area of ~95 square
degrees. For four fields we also obtained 608 MHz observations, for the
remaining two fields 608 MHz observations were already available. This
online version of the catalog merges the source catalogues at both
frequencies. These data were originally part of a PhD-thesis at Leiden
Observatory by M.H. Wieringa (1991).
1 name Name of source (char8, example: '76W0771*')
2 freq MHz Frequency of source detection in MHz (int, example: 327 or 608)
3 ra_1950 radians B1950 Right Ascension (in radians) (real, example: 2.328327)
4 ra_1950_deg degrees B1950 Right Ascension (in degrees) (real, example: 133.403290)
5 ra_err seconds Error in RA (real, example: 0.39)
6 dec_1950 radians B1950 Declination (in radians) (real, example: 69.880000)
7 dec_1950_deg degrees B1950 Declination (in degrees) (real, example: 1.220000)
8 dec_err arcsec Error in RA (real, example: 0.39)
9 flux mJy Flux Density at frequency listed (real, example: 418.11)
10 flux_err mJy Error on flux density (real, example: 14.00)
11 res Flag indicating whether source is resolved (char1, example: 'U' or 'R' or 'E')
12 limit Flag indicating size is upper limit (char1, example: '<')
13 maj_axis arcsec Major axis (FWHM) of fitted gaussian (real, example: 73.2)
14 maj_err arcsec Error on major axis (real, example: 5.2)
15 pos_ang degrees Position angle in degrees (N through E) (int, example: 136)
16 pos_err degrees Error on PA (int, example: 5)
17 min_axis arcsec Minor axis (FWHM) of fitted gaussian (real, example: 74.3)
18 ratio Ratio of total flux to fitted peakflux (real, example: 1.6)
19 snr Peak signal to noise ratio of source in map (real, example: 233.72)
20 atten Primary beam attenuation (>1) (real, example: 2.87)
21 weight Statistical weight for use in source counts (real, example: 1.0)
1. COLUMN name
This columns contains the name of the source composed of
the Westerbork survey name + source number in form nnWmmmmM,
where nn is Westerbork survey number, mmmm the source sequence
number and M is ' ' for single sources, '*' for multiples, 'A',
'B', 'C',... for components.
Sources detected at both frequencies have corresponding
numbers in the 327 MHz (92cm) and 608 MHz (50cm) lists, but
components of multiple sources do not necessarily correspond
between the two frequencies. Also in some cases one or more
components may not be detected at the other frequency.
The Westerbork survey numbers are as follows:
64W2: Lynx, 327 MHz only (this field has been mapped at this
frequency before by M.J.A. Oort (thesis), with a 2 appended
to the W to indicate the revised list), numbers do not
correspond because the present survey is more sensitive.
69W : Draco, a survey of 2 overlapping fields at 327 MHz and 6 fields
at 608 MHz.
70W : Umi, 327 MHz only, one field.
75W : OH471, one 327 MHz field and three 608 MHz fields
76W : Cam, one 327 MHz field and three 608 MHz fields
Example (name) (char8): '76W0771*'
2. COLUMN freq
This column indicates whether the source was observed at 327
or 608 MHz.
Example (freq) (int): 327 or 608
3. COLUMNS ra_1950 ra_1950_deg dec_1950 dec_1950_deg
These columns give the B1950 right ascension and declination,
in radians and in degrees.
Example (ra_1950) (real): 2.328327
Example (ra_1950_deg) (real): 133.403290
Example (dec_1950) (real): 69.880000
Example (dec_1950_deg) (real): 1.220000
4. COLUMNS ra_err dec_err
These columns give the error on right ascension (in seconds of
time) and declination (in arcsec).
Example (ra_err) (real): 0.39
Example (dec_err) (real): 0.39
5. COLUMNS flux flux_err
These columns give the flux density and error, in mJy, of the
source at the frequency given in the freq column. The data were
calibrated using the DWARF redundancy package and absolute calibration
is based on 3C286, using a flux of 26.93 Jy at 327 MHz and 21.47 Jy
at 608 MHz. The source parameters were determined using a gaussian
fitting procedure for all but the most complex sources and statistical
corrections for noise bias were applied.
Example (flux) (real): 418.11
Example (flux_err) (real): 14.00
6. COLUMN res
This column gives a flag indicating whether or not the source was
resolved. The following are used:
R: resolved, fitted gaussian parameters follow
E: extended, multiple components found and given
on subsequent lines)
Example (res) (char1): 'U' or 'R' or 'E'
7. COLUMN limit
This column is marked with a '<' if the size that follows
is an estimated upper limit (for unresolved sources).
Example (limit) (char1): '<'
8. COLUMNS maj_axis maj_err min_axis
These columns give information on the size of the source.
The major axis (FWHM) of the fitted gaussian (for resolved sources)
or maximum component separation (for extended sources) is given
(in arcsec) in the maj_axis column. The error in major axis (in
arcsec) is given in the maj_err column. The minor axis (FWHM)
of the fitted gaussian (in arcsec) is given in the min_axis column.
Example (maj_axis) (real): 73.2
Example (maj_err) (real): 5.2
Example (min_axis) (real): 74.3
9. COLUMNS pos_ang pos_err
These columns give the position angle and error in position
angle, in degrees. The angle is measured North through East.
Example (pos_ang) (int): 136
Example (pos_err) (int): 5
10. COLUMN ratio
This column gives the ratio of total flux to fitted peakflux.
Example (ratio) (real): 1.6
11. COLUMN snr
This column gives the peak signal to noise ratio of the source.
Example (snr) (real): 233.72
12. COLUMN atten
This column gives the primary beam attenuation (>1).
Example (atten) (real): 2.87
13. COLUMN weight
This column gives the statistical weight for use in source
Example (weight) (real): 1.0
Wieringa, M.H., 1991, Thesis, Leiden Univ.
Wieringa, M.H., 1993, Bull. Inf. CDS 43, 17.
Origin submitted by M.H. Wieringa
Columns 21 Rows 5850
For catalog content:
C. Stern Grant, SAO; firstname.lastname@example.org (8/94)