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WENSS - Westerbork Northern Sky Survey

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Overview

The Westerbork Northern Sky Survey (WENSS) is a low-frequency radio survey that covers the whole sky north of declination +30 degrees at a wavelength of 92 cm to a limiting flux density of approximately 18 milliJanskies (mJy) at the 5 sigma level. WENSS is a collaboration between the Netherlands Foundation for Research in Astronomy (NFRA/ASTRON) and the Leiden Observatory. The major personnel involved in WENSS include Ger de Bruyn, George Miley, Roeland Rengelink, Yuan Tang, Malcolm Bremer, Huub Rottgering, Ernst Raimond, Martin Bremer, and David Fullagar.

The version of the WENSS Catalog as implemented at the HEASARC is a union of two separate catalogs obtained from the WENSS Website: the WENSS Polar Catalog (18186 sources above +72 degrees declination) and the WENSS Main Catalog (211234 sources in the declination region from +28 to +76 degrees).


Catalog Bibcode

1997A&AS..124..259R

References

    Rengelink et al. 1997 A&A Supplement Ser., Vol. 124, 259-280

Provenance

This database table was created by the HEASARC in February 2001 based on the tables wenssn10.cat (WENSS Main Catalog) and wenssp10.cat (WENSS Polar Catalog) obtained from the WENSS web site at http://www.strw.leidenuniv.nl/

HEASARC Changes

In order to create a unique name for each entry in this database, the HEASARC has appended lower-case characters 'a', 'b', etc. to what would otherwise be duplicate names, e.g., 'WN 0000.0+3207a' and 'WN 0000.0+3207b'. It appears that most, if not all, of such cases are situations were the source lies in an overlap region of two or more 'frames' and was detected independently in these different frames. Thus, when referring to the source name in a paper, the lower-case prefix should in general be omitted. Notice that the original WENSS Catalog also contains some multi-component sources, e.g., 'WN 0000.1+3929', for which the catalog creators list an entry both for the source as a whole and also for its individual components which have the same name but with upper-case characters 'A', 'B', etc., appended, e.g., 'WN 0000.1+3929A' and 'WN 0000.1+3929B'. The HEASARC has also changed the name prefix from the 'WNB' found in the original catalog to 'WN ' in order that the names conform to those recommended in the Dictionary of Nomenclature of Celestial Objects maintained at the CDS (http://vizier.u-strasbg.fr/cgi-bin/Dic).

Parameters

Name
The WENSS Catalog designation in the form recommended in the Dictionary of Nomenclature of Celestial Objects maintained at the CDS (http://vizier.u-strasbg.fr/cgi-bin/Dic). In order to create a unique name for each entry in this database, the HEASARC has appended lower-case characters 'a', 'b', etc. in order of increasing right ascension (B1950) to what would otherwise be duplicate names, e.g., 'WN 0000.0+3207a' and 'WN 0000.0+3207b'. It appears that most, if not all, of such cases are situations were the source lies in an overlap region of two or more 'frames' and was detected independently in these different frames. Thus, when referring to the source name in a paper, the lower-case prefix should in general be omitted. Notice that the WENSS Catalog also contains some multi-component sources, e.g., 'WN 0000.1+3929', for which the catalog creators list an entry both for the source as a whole and also for its individual components which have the same name but with upper-case characters 'A', 'B', etc., appended, e.g., 'WN 0000.1+3929A' and 'WN 0000.1+3929B'.

RA
The Right Ascension of the radio source in the selected equinox. This was given to a precision of 0.01 seconds of time and in both B1950 and J2000 equaorial coordinates in the original catalog tables.

Dec
The Declination of the radio source in the selected equinox. This was given to a precision of 0.1 arcseconds and in both B1950 and J2000 equaorial coordinates in the original catalog tables.

LII
The Galactic Longitude of the radio source.

BII
The Galactic Latitude of the radio source.

Source_Type
This is a flag that describes the source type: 'S' means a single-component source, 'M' means a multi-component source, 'C' means that this is a component of a multi-component source,and 'E' means that this is an extended source which required more than four components to fit.

Fit_Problem
This is a flag that is set to 'Y' to indicate that there were problems in the model fitting for a source.

Flux_92_cm
The peak flux density of the source at 92 cm (325 MHz), in mJy/beam.

Flux_92_cm_Error
The local RMS noise level, in mJy/beam.

Int_Flux_92_cm
The integrated flux density of the source at 92 cm (325 MHz), in mJy.

Major_Axis
For sources that are probably resolved, i.e., for which the ratio of integrated to peak flux densities exceeds a signal-to-noise dependent threshold, this is the major axis in arcseconds. The threshold is the integrated to peak flux density ratio below which 95% of the unresolved sources are located.

Minor_Axis
For sources that are probably resolved, i.e., for which the ratio of integrated to peak flux densities exceeds a signal-to-noise dependent threshold, this is the minor axis in arcseconds. The threshold is the integrated to peak flux density ratio below which 95% of the unresolved sources are located.

Position_Angle
The position angle, in degrees, for those sources that are probably resolved, i.e., for which the ratio of integrated to peak flux densities exceeds a signal-to-noise dependent threshold, namely, the integrated to peak flux density ratio below which 95% of the unresolved sources are located.

Frame
The 6 by 6 degree `frame' (on a 5 by 5 degree grid) from which the source was obtained. The map center coordinates of these frames are listed in Table 4 of the published Rengelink et al. 1997 paper describing this catalog.


Contact Person

Questions regarding the WENSS database table can be addressed to the HEASARC User Hotline.
Page Author: Browse Software Development Team
Last Modified: Thursday, 23-Mar-2006 01:19:41 EST