The Discovery of a Small Group of Galaxies in Ursa Major by the Hubble Space Telescope

Abstract

We present HST/WFPC2 images of a previously unknown loose group of galaxies in Ursa Major. These images were obtained as part of the GTO parallel program in which WFPC2 images are taken using the F606W (wide V) and F814W (I band) filters in parallel with GTO observations using other HST instruments. These WFPC2 images, obtained in parallel with FGS observations of BD +67552^deg^ on 1994 April 22 contain a number of galaxies between 4" and 11" in diameter as well as a multitude of other, smaller galaxies. The group is dominated by eight spiral galaxies and one elliptical galaxy in an area smaller than one Wide Field Camera chip (80"X 80"). We present V and I band photometry, V-I colors, and V-I color gradients of each galaxy in the group. The luminosity function provides evidence that the smaller, fainter galaxies are background to the group. We estimate the redshift of the cluster to be z ~ 0.2(H_0_ = 75 and q_0_ = 0).