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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.
| Arcsecond Positions of UGC Galaxies
We present accurate B1950 and J2000 positions for all confirmed galaxiesin the Uppsala General Catalog (UGC). The positions were measuredvisually from Digitized Sky Survey images with rms uncertaintiesσ<=[(1.2")2+(θ/100)2]1/2,where θ is the major-axis diameter. We compared each galaxymeasured with the original UGC description to ensure high reliability.The full position list is available in the electronic version only.
| Corrections and additions to the third reference catalogue of bright galaxies
List of corrections and additions to the Third Reference Catalogue ofBright Galaxies (RC3) are given. The corrected version of the catalogue(RC3.9b), dated April 1994, is currently available through the nationaldata centers.
| Galaxy structures in the Hercules region
216 redshifts have been obtained in a region of 981 sq deg south of theHercules supercluster. 172 of these redshifts are of galaxies withmpg less than or equal to 15.1, 110 of which had no previousvelocity measurement. 44 new redshifts are of galaxies fainter thanmpg = 15.1. With these new data we have been able to define asample in a vast region (approximately 1700 sq deg) around Herculeslimited to mpg less than or equal to 15.1 with a velocitycompleteness of 81.5%. 189 galaxies have been morphologically classifiedso that all galaxies in the sample with known velocity now also haveknown morphology. The magnitude limited sample, including 556 galaxies,is then used to identify and describe galaxy structures in the region.We find that the overdense volume is small, that its overall appearanceis that of a coral branch floating in a sea of nothing and that earlyand late type galaxies defined different structures.
| Optical positions and 327 MHz flux-densities of UGC galaxies in selected Westerbork fields
The study presents accurate optical positions of 421 UGC galaxies whichare used to search for 30 92-cm WSRT fields observed for emission fromthese galaxies. Good 92-cm flux densities were obtained for 140galaxies, marginal flux densities for 71 galaxies, and upper limits for210 galaxies. For 35 galaxies, spectral indices in the decimeterwavelength range are determined. The mean spectral index for spiralgalaxies (0.72 +/- 0.03) is very similar to that of elliptical galaxies(0.64 +/- 0.10). The four multiple systems in the sample have a muchflatter spectral index (-0.21 +/- 0.07), from which the presence of asignificant thermal component in their total radio emission issuggested. Comparison with IRAS results show that about half of thegalaxies detected at radio wavelengths are detected in the FIR. It isproposed that some spiral galaxies are anomalously weak in the IR ascompared with their radio brightness.
| The distribution of galaxies around NGC 5846
The present study investigates the 3D distribution of galaxies in aregion surrounding the chain of galaxies in the NGC 5846 group bysubjective and objective tests for clustering. The results of anautomated search, in which a percolation algorithm is applied to aredshift sample complete in magnitude not greater than 14.9, arecompared with those of the subjective impressions. At a number densityenhancement of 20 over the mean background, eight large groups whichwere not affected by incompleteness at very low declinations areidentified. Four of these groups - the Virgo II cloud, the NGC 5846group, and groups 139 and 148 from the list of GH - are nearby. VirgoIII is loose and irregular whereas NGC 5846 is dense and symmetric. Theother two groups are small compact clumps. The conclusions are inagreement with a study by Tully (1982) that these four nearby groupsform a prolate cloud with an overall density contrast over the mean ofabout 10, and that this cloud lies out of the supergalactic plane andpoints toward the Virgo cluster.
| Structure of superclusters and superclusters formation. IV Spatial distribution of clusters of galaxies in the Coma supercluster and its large-scale environment
The Coma-A1367 Supercluster and its large-scale environment areinvestigated. The Zwicky et al. (1961-68) clusters are used assupercluster tracers; superclusters are defined not by visual impressionbut on the basis of cluster analysis. Attention is restricted to an areaof the sky where RA is between 9h and 15h, with Dec. greater than -3deg. Clustering analysis is applied to study the spatial distribution.At neighborhood radii R = 15-25 Mpc (for Hubble constant H = 50 km per sper Mpc), the clusters form chains and superclusters of galaxies. It isnoted that at R = 26-28 Mpc, superclusters merge to a single connectednetwork. Cluster chains link the Coma-A1367 Supercluster with the LocalSupercluster, A779, and Hercules Superclusters. The Coma-A1367Supercluster comprises four cluster chains, and its diameter is greaterthan 100 Mpc. It is noted that a typical cluster chain has eight Zwickyclusters and is 80 Mpc in length. Most, if not all, of the clusters formconnected systems. Empty regions devoid of clusters have diameters up to100 Mpc in this region of the sky. The morphology distribution of brightgalaxies and the mean absolute magnitude of first ranked galaxies inZwicky clusters are found to be similar to the respective quantities inAbell clusters.
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