We apply a friends-of-friends algorithm to the combined Updated Zwicky Catalog and Southern Sky Redshift Survey to construct a catalog of 1168 groups of galaxies; 411 of these groups have five or more members within the redshift survey. The group catalog covers 4.69 sr, and all groups exceed the number density contrast threshold, / = 80. We demonstrate that the groups catalog is homogeneous across the two underlying redshift surveys; the catalog of groups and their members thus provides a basis for other statistical studies of the large-scale distribution of groups and their physical properties. The median physical properties of the groups are similar to those for groups derived from independent surveys, including the ESO Key Programme and the Las Campanas Redshift Survey. We include tables of groups and their members.

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In this paper we describe the Nearby Optical Galaxy (NOG) sample, which is a complete, distance-limited (cz ≤6000 km/s) and magnitude-limited (B≤14) sample of ∼7000 optical galaxies. The sample covers 2/3 (8.27 sr) of the sky (|b| > 20 • ) and appears to have a good completeness in redshift (98%). We select the sample on the basis of homogenized corrected total blue magnitudes in order to minimize systematic effects in galaxy sampling.We identify the groups in this sample by means of both the hierarchical and the percolation friends of friends methods. The resulting catalogs of loose groups appear to be similar and are among the largest catalogs of groups presently available. Most of the NOG galaxies (∼60%) are found to be members of galaxy pairs (∼580 pairs for a total of ∼15% of objects) or groups with at least three members (∼500 groups for a total of ∼45% of objects). About 40% of galaxies are left ungrouped (field galaxies).We illustrate the main features of the NOG galaxy distribution. Compared to previous optical and IRAS galaxy samples, the NOG provides a denser sampling of the galaxy distribution in the nearby universe. Given its large sky coverage, the identification of groups, and its high-density sampling, the NOG is suited for the analysis of the galaxy density field of the nearby universe, especially on small scales.

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