Nearby Groups of Galaxies. II. an All-Sky Survey within 3000 Kilometers per Second

The 2367 galaxies in the Nearby Galaxies Catalog (Tully, 1987) have been assigned to clouds, associations, and groups. The group assignments follow from a dendogram analysis with linkages based on an estimator of the gravitational force between entities. The procedure naturally accounts for the effects of tides. Groups are defined by a specific density threshold. Within the radius of reasonable completion of 25/h75 Mpc, 179 groups have been identified that include 69 percent of the known galaxies and 77 percent of the light. An additional 20 percent of the galaxies are in associations, and 10 percent of the galaxies are at-large in clouds. Less than 1 percent of galaxies are by themselves outside of clouds. Evidence is presented that the groups are collapsed and that many should be virialized. There is no indication of a serious interloper problem. The properties of the 49 groups with five or more members show less scatter than was the case with previously identified groups. The median virial radius is 340/h75 kpc, the median velocity dispersion is 100 km/s, and the median value of M(V)/L(B)(b, i) is 94h75 (solar mass)/(solar luminosity).