Magnitudes and Colors for the Star Clusters in M31.

Magnitudes and colors on the B, V system have been derived photographically for 121 star clusters in M31 for which no colors were previously available, using clusters with photoelectric magnitudes as standards. A sequence of clusters is found, with B - V < +05 and V> 160, which is similar to one found by Hiltner in M33. These clusters, which occur with a flattened distribution in the outer parts of M31, are likely to contain stars in an earlier stage of evolution than those in globular clusters. The luminosity function of the clusters in M31, after correction for absorption, suggests that M31 may contain some globular clusters brighter than those found in the Galaxy. The distribution of observed reddened clusters is asymmmetric about both the major and the minor axes of M13. The distribution along the minor axis is consistent with the picture of obscuration extending into the nucleus and the northpreceding side of the Galaxy being the nearer. A group of apparently reddened clusters is found outside the region of high star density, where 21-cm observations indicate a high density of neutral hydrogen. Assuming a tilt angle of M31 of 75?5, the clusters out to a distance of 12 kpc from the nucleus have a spheroidal distribution with an axial ratio (b/a) of 045.