The Astronomy Department of the University of Virginia intends to acquire a Perkin.Elmer PDS microdensitometer and accessories. The PDS will be used primarily in conjunction with the large (over 146,000) collection of astrometric plates in the files of the Leander McCormick Observatory. The measuring engine with a laser interferometry coordinate readout will improve accuracy and productivity in the existing astrometric programs. The astrometric projects which will benefit most from the PDS include: 1) studies of parallaxes of Hyades cluster members, white dwarfs and the population II main sequence stars; and 2) analysis of astrometric binaries. Studies where the PDS system will contribute to ongoing research in the department include: 1) surface photometry in faint outlying regions of spiral galaxies; 2) determinations of the luminosity function for clusters of galaxies; 3) detection and measurement of Hydrogen alpha from emission line galaxies in clusters; and 4) analysis of ground-based optical data of interesting ultraviolet (UV) sources found in the Ultraviolet Imaging Telescope program.
