THE ASTRONOMICAL JOURNAL    VOLUME 112, NUMBER 6, PAGE 2471       DECEMBER 1996

   THE URSA MAJOR CLUSTER OF GALAXIES. I. CLUSTER DEFINITION AND PHOTOMETRIC
                                     DATA

                                R. BRENT TULLY

     Institute for Astronomy, University of Hawaii, Honolulu, Hawaii 96822
                  Electronic mail: tully@uhifa.ifa.hawaii.edu

                             MARC A. W. VERHEIJEN

            Kapteyn Astronomical Institute, University of Groningen

                               MICHAEL J. PIERCE

         Department of Astronomy, Indiana University, Swain Hall West,
                             Bloomington, IN 47405
                  Electronic mail: mpierce@astro.indiana.edu

                   JIA-SHENG HUANG AND RICHARD J. WAINSCOAT

     Institute for Astronomy, University of Hawaii, Honolulu, Hawaii 96822


                                   ABSTRACT

    The Ursa Major Cluster has received remarkably little attention,
    although it is as near as the Virgo Cluster and contains a comparable
    number of H I-rich galaxies.  In this paper, criteria for group
    membership are discussed and data are presented for 79 galaxies
    identified with the group.  Of these, all 79 have been imaged at B,R,I
    bands with CCDs, 70 have been imaged at K' with a HgCdTe array
    detector, and 70 have been detected in the H I 21 cm line.  A complete
    sample of 62 galaxies brighter than M_B = -16.5 is identified.  Images
    and gradients in surface brightness and color are presented at a common
    linear scale.  As has been seen previously, the galaxies with the
    reddest global colors are reddest at the centers and get bluer at large
    radii.  However, curiously, among the galaxies with the bluest global
    colors there are systems with very blue cores that get redder at large
    radii.