Radial velocities and masses of galaxies in groups from 21-centimeter line observations.

New 21-cm radial velocities are given for 50 galaxies. The mean error of a determination is typically 9 km s '. Conventional Bottlinger-Lohman total masses are derived for these galaxies from the width of 21-cm line profiles. Comparison of new 21-cm radial velocities with values tabulated in the Reference Catalogue of Bright Galaxies (BGC) indicates that, except for an occasional anomalous value, the BGC velocities have accuracies well described by their listed mean errors. The 21-cm velocities and galactic masses are used to estimate directly Mvt (virial mass) and M (sum of the conventional masses of component galaxies) for six de Vaucouleurs groups. Groups 5, 6, 9, 12, 33, and 51 have Mvt/M = 15, 44, 3, 28, 75, and 590, respectively. The M101 and M51 groups, which together comprise group 5, each have Mvt/M = 1. Subject headings: galaxies: clusters of - radio sources: 21-cm radiation