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The UZC-SSRS2 Group Catalog
We apply a friends-of-friends algorithm to the combined Updated ZwickyCatalog and Southern Sky Redshift Survey to construct a catalog of 1168groups of galaxies; 411 of these groups have five or more members withinthe redshift survey. The group catalog covers 4.69 sr, and all groupsexceed the number density contrast threshold, δρ/ρ=80. Wedemonstrate that the groups catalog is homogeneous across the twounderlying redshift surveys; the catalog of groups and their membersthus provides a basis for other statistical studies of the large-scaledistribution of groups and their physical properties. The medianphysical properties of the groups are similar to those for groupsderived from independent surveys, including the ESO Key Programme andthe Las Campanas Redshift Survey. We include tables of groups and theirmembers.
| Substructure in Clusters Containing Wide-Angle-Tailed Radio Galaxies. I. New Redshifts
We present new redshifts and positions for 635 galaxies in nine richclusters containing wide-angle tailed (WAT) radio galaxies. Combinedwith existing data, we now have a sample of 18 WAT-containing clusterswith more than 10 redshifts. This sample contains a substantial portionof the WAT clusters in the VLA 20 cm survey of Abell clusters, including75% of WAT clusters in the complete survey (z<=0.09), and 20% of WATclusters with z>0.09. It is a representative sample, which should notcontain biases other than selection by radio morphology. We graphicallypresent the new data using histograms and sky maps. A semiautomatedprocedure is used to search for emission lines in the spectra in orderto add and verify galaxy redshifts. We find that the average apparentfraction of emission-line galaxies is about 9% in both the clusters andthe field. We investigate the magnitude completeness of our redshiftsurveys with CCD data for a test case, Abell 690. This case indicatesthat our galaxy target lists are deeper than the detection limit of atypical MX exposure, and they are 82% complete down to R=19.0. Theimportance of the uniformity of the placement of fibers on targets isposited, and we evaluate this in our data sets. We find some cases ofnonuniformities which may influence dynamical analyses. A second paperwill use this database to look for correlations between the WAT radiomorphology and the cluster's dynamical state.
| Galaxy coordinates. II. Accurate equatorial coordinates for 17298 galaxies
Using images of the Digitized Sky Survey we measured coodinates for17298 galaxies having poorly defined coordinates. As a control, wemeasured with the same method 1522 galaxies having accurate coordinates.The comparison with our own measurements shows that the accuracy of themethod is about 6 arcsec on each axis (RA and DEC).
| Accurate Positions for MCG Galaxies
We have measured accurate celestial coordinates for 4741 extragalacticobjects, primarily drawn from a list of MCG galaxies with no recentlypublished accurate positions. The standard deviations in the newpositions depend slightly on the measurement method but are on the orderof 1.0" to 1.2". Standard deviations in the original MCG positions areconfirmed to be at the 1.5′-2.0′ level. These new positionswere integrated into NED in 1997 December.
| A redshift survey toward a proposed void of galaxies suggested by the distribution of Abell clusters
A program of redshift measurements was carried out in a region of thesky in which a relative under-density of Abell clusters had been used toinfer the presence of a large (diameter about 40/h Mpc) void in thegeneral galaxy distribution. The purpose of this study was toinvestigate whether the large-scale distribution of galaxies is tracedby the distribution of rich clusters. Redshifts are presented for 308galaxies in the Zwicky Catalog in a 234 square degree region centered onR.A. about 2h, Decl. about 12 deg of which 229 have been newly measured.These data reveal a pattern of filamentary structure alternating withvoids of characteristic diameter about 25-30/h Mpc, throughout thevolume sampled. While the redshift data reveal an underdensity in thedistribution of galaxies in the general region suggested by the Abellcluster distribution, they do not support the existence there of a 40/hMpc diameter void.
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