A Hubble Space Telescope Catalog of 449 Galaxies Seen Through the Disk
  of M31
  From inspection of 30 Hubble Space Telescope ACS images of M31, we provide a
catalog of 449 galaxies seen through the spiral disk. Measurements of the
positions of the galaxies, their integrated magnitudes in two colors and their
sizes, determined from isophotometry, are included in the catalog. We discuss
the many difficulties of interpreting these data in terms of the effects of
intervening extinction by dust in the disk
