Advanced Camera for Surveys Imaging of 25 Galaxies in Nearby Groups and in the Field

We present Hubble Space Telescope Advanced Camera for Surveys images and color-magnitude diagrams for 25 nearby galaxies with radial velocities VLG < 500 km s-1. Distances are determined based on the luminosities of stars at the tip of the red giant branch that range from 2 to 12 Mpc. Two of the galaxies, NGC 4163 and IC 4662, are found to be the nearest known representatives of blue compact dwarf objects. Using high-quality data on distances and radial velocities of 110 nearby field galaxies, we derive their mean Hubble ratio to be 68 km s-1 Mpc-1 with a standard deviation of 15 km s-1 Mpc-1. Peculiar velocities of most of the galaxies, Vpec = VLG - 68D, follow a Gaussian distribution with σv = 63 km s-1 but with a tail toward high negative values. Our data display the known correlation between peculiar velocity and galaxy elevation above the Local Supercluster plane. The small observed fraction of galaxies with high peculiar velocities, Vpec < -500 km s-1, may be understood as objects associated with nearby groups (Coma I, Eridanus) outside the local volume.