Browse
this table...

WBL - WBL Poor Galaxy Clusters Catalog (White et al. 1999)

HEASARC
Archive

Overview

The Catalog of Nearby Poor Clusters of Galaxies of White et al. (1999), also known as the WBL Catalog, is a catalog of 732 optically selected, nearby poor clusters of galaxies covering the entire sky north of -3 degrees declination. The poor clusters, called WBL clusters, were identified as concentrations of three or more galaxies with photographic magnitudes brighter than 15.7, possessing a galaxy surface overdensity of 10^(4/3). These criteria are consistent with those used in the identification of the original Yerkes poor clusters, and this new catalog substantially increases the sample size of such objects. These poor clusters cover the entire range of galaxy associations up to and including Abell clusters, systematically including poor and rich galaxy systems spanning over 3 orders of magnitude in the cluster mass function. As a result, this new catalog contains a greater diversity of richness and structures than other group catalogs, such as the Hickson and Yerkes catalogs. This table contains the entries for the clusters (given in Table 2 of the published catalog) and includes redshift data (where available) and cross-references to other group and cluster catalogs. The WBLGALAXY table (q.v.) contains the entries for the individual galaxies in the clusters which ere given in Table 3 of the published catalog.

Catalog Bibcode

1999AJ....118.2014W

References

A catalog of nearby poor clusters of galaxies
       White R.A., Bliton M., Bhavsar S.P., Bornmann P., Burns J.O.,
       Ledlow M.J., Loken C.
      <Astron. J. 118, 2014 (1999)>
      =1999AJ....118.2014W      (SIMBAD/NED BibCode)

Provenance

The WBL table was created by the HEASARC in July 2002 based on CDS Catalog J/AJ/118/2014 (the file table2.dat).

Parameters

Name
The WBL designation of the poor cluster (WBL NNN).

RA
The Right Ascension of the centroid of the poor cluster in the selected equinox. This was given in equinox B1950.0 and with a precision of 0.1 minutes of time in the original table. The centroid was determined from a luminosity-weighted mean of all member galaxies listed in the Zwicky Catalog of Galaxies and Clusters of Galaxies (CGCG). Luminosities L were computed as L = 10^(-0.4 m_pg), where m_pg is the apparent photographic magnitude, and used as the weight in computing the luminosity-weighted mean right ascension and declination for each cluster.

Dec
The Declination of the centroid of the poor cluster in the selected equinox. This was given in equinox B1950.0 and with a precision of 1 arcminute in the original table. The centroid was determined from a luminosity-weighted mean of all member galaxies listed in the Zwicky Catalog of Galaxies and Clusters of Galaxies (CGCG). Luminosities L were computed as L = 10^(-0.4 m_pg), where m_pg is the apparent photographic magnitude, and used as the weight in computing the luminosity-weighted mean right ascension and declination for each cluster.

LII
The Galactic Longitude of the centroid of the poor cluster.

BII
The Galactic Latitude of the centroid of the poor cluster.

Richness
The richness of the poor cluster, defined as the number of CGCG galaxies in the poor cluster.

Subclustering
The clustering at the sigma_46 level. An indication of the fate of each individual galaxy at the higher density enhancement (sigma_46). A single zero in this column indicates that a group at sigma_21 fractured into single galaxies at sigma_46, i.e., the galaxy apertures did not overlap. Combinations of other numbers indicate how many galaxies were in each subcluster at sigma_46, with "0" indicating one or more isolated galaxies. For example, a cluster with 11 members and an "8+0" in this column becomes a group of eight members with three isolated galaxies at sigma_46, while a cluster of 11 members and an entry of "4+3+2+0"breaks up into three subclusters of four, three, and two members, with two isolated galaxies at sigma_46.

Redshift
The poor-cluster redshift. The redshift for the cluster, when available, is computed as an average of redshifts from the literature obtained through the NASA Extragalactic Database (NED).

Num_Galaxy_Redshifts
The number of galaxy redshifts for the poor cluster that were available from NED.

Note_Redshift
A flag for notes on the determination of the cluster redshift. If there is no note (the parameter value is blank), then the number of galaxy redshifts listed in the num_galaxy_redshifts parameter was used to compute the cluster redshift.

If the value is "i", there were only two redshifts available and their values differed by more than 1500 km s^(-1) and, in this case, the two galaxies may be close only in projection. The redshift given in this case is the average of the two galaxy redshifts.

If the value is "ii", this indicates that, of the three or more redshifts available, one was more than 1500 km s^(-1) from the mean. After removing this discrepant redshift, a new mean was calculated, with all remaining redshifts within 1500 km s^(-1) of this new mean.

If the value is "iii", this indicates that, of the three or more redshifts available, at least two discrepant redshifts were present. The redshift listed is then the mean redshift calculated after removing only the most discrepant velocity.

Zwicky_Cluster
The name of the Zwicky cluster containing the given WBL cluster within its contours. Zwicky clusters are rarely spherical, so all correlations were verified by (the authors') eye. Zwicky clusters are also separated into estimated distance classes, with near clusters meant to be in the redshift (z) range 0.0 < z <= 0.05 and medium-distant clusters in the range 0.05 < z <= 0.1 (CGCG). The authors included any near or medium-distant Zwicky cluster that contained a WBL cluster within its contours. Near clusters were chosen over medium-distant clusters in the very few cases where a poor cluster fell within the boundaries of two Zwicky clusters of different distance classes. The parameter medium_distant_flag is set to "MD" to indicate that the associated Zwicky cluster ia a medium-distant cluster.

Medium_Distant_Flag
This flag is set to "MD" to indicate that the associated Zwicky cluster ia a medium-distant cluster.

Rad_Zwicky_Cluster
The radius of the Zwicky cluster, R_Z,in arcminutes. This radius is that given in the CGCG and is meant to indicate the area on the sky contained within the hand-drawn contours.

WBL_Zwicky_Offset
The angular distance between the center of the Zwicky and WBL clusters, in units of the Zwicky cluster radius, R_Z.

Abell_Cluster
The Abell cluster cross-correlated with the poor cluster. Any WBL cluster located within one corrected Abell radius (Abell et al. 1989, ApJS, 70, 1) of a distance class 3 or nearer Abell cluster was considered as associated with the Abell cluster. In addition, NED was used to search for WBL cluster members that were also members of Abell clusters.

CfA_Group
The CfA Redshift Catalog group cross-correlated with the poor cluster. Associated CfA groups were identified as groups whose coordinates were within 30 arcminutes of the WBL centroid.

HCG_Group
The Hickson compact group (HCG) cross-correlated with the poor cluster. Associated Hickson compact groups were identified from information on individual galaxies obtained through NED.

Yerkes_Cluster
The Yerkes cluster cross-correlated with the poor cluster. The identification of WBL clusters associated with the Yerkes clusters was determined visually as a part of the development of the WBL catalog.

Class
The HEASARC Browse object classification: all entries in this table have been given the same generic classification of "cluster of galaxies".


Contact Person

Questions regarding the WBL database table can be addressed to the HEASARC User Hotline.

Page Author: Browse Software Development Team
Last Modified: 8-Nov-2004