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ZWCLUSTERS: Help

ZWCLUSTERS - Zwicky Clusters


Overview

The ZWCLUSTERS database is based upon the Catalogue of Zwicky Clusters of Galaxies. The Zwicky clusters were identified by F. Zwicky in 560 POSS fields. They are rich clusters, each having at least 50 members within 3 magnitudes of the brightest member.

Catalog Bibcode

1961CGCG..C......0Z

References

Zwicky, F., et al., 1961-68, Catalogue of Galaxies and of Clusters of Galaxies (Pasadena, California Institute of Technology, 6 vols.).

Parameters

Name
Designation derived from the Zwicky cluster number. Cluster number (1...9134). This file is in ascending order by B1950.0 right ascension, whereas the original published catalogue is sorted by the survey field number and a running number within each survey field.

RA_1950
Right Ascension in 1950 Coordinates

Dec_1950
Declination in 1950 Coordinates

LII
The galactic longitude of the object.

BII
The galactic latitude of the object.

Cluster_Type
Cluster types are 1 for open, 2 for medium compact, or 3 for compact.

Cluster_Pop
The counted number of galaxies in the cluster.

Diameter
The measured diameter of the cluster in centimeters.

Dist_Group
Distance group, as estimated by Zwicky: 1 for near, 2 for medium distant, 3 for distant, 4 for very distant, or 5 for extremely distant.

Lamb_Distance
Lambert coordinates. The Lambert tranformation is an equal-area projection. The Lambert distance RL from the nearest galactic pole is defined by RL = 2 sin ((90-b)/2), with RL > 0 for the north galactic hemisphere, and RL < 0 for the south galactic hemisphere.

Lamb_X
Lambert coordinates. The X Lambert coordinate XL = 2 sin l sin ((90-b)/2).

Lamb_Y
Lambert coordinates. The Y Lambert coordinate YL = 2 cos l sin ((90-b)/2).

Sglon
The supergalactic longitude of the object.

Sglat
The supergalactic latitude of the object.

Cluster_Radius
The cluster radius in degrees calculated as <clusrad> = 0.09326 * Diameter.

Cluster_Area
The cluster area in square degrees: 0.02733 * Diameter^2.

Mean_Pop
The mean apparent population (galaxies per square degree): population/area, taken from Cluster Pop and Cluster Area

RA
The Right Ascension of the object.

Dec
The Declination of the object.

CRA
Right Ascension, Sexagesimal, J2000

CDec
Declination, Sexagesimal, J2000

Class
BROWSE classification type.


Contact Person

Questions regarding the ZWCLUSTERS database table can be addressed to the HEASARC User Hotline.
If you have any problems, please consult the help page or mail ledas-help@star.le.ac.uk
 
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