A New Faint Globular Cluster
Halton C. Arp, Sydney van den Bergh · Publications of the Astronomical Society of the Pacific · 1960
In 1958 van den Bergh discovered a faint cluster on the Palomar Sky Survey prints in the position: a = 16 h 09 m 20 s , 0 = +15°03 '(1960).Exposures by Arp with the 200-inch corrected to f/4.7 reveal that the object is a faint star cluster.The cluster appears similar to Abell Nos. 3 and 4, 1 studied by Mrs. Burbidge and Sandage, 2 but it is somewhat poorer than any in Abell's list.Plate I shows the appearance of the cluster.Preliminary photoelectric measures with the 200-inch indicate that the cluster has a giant branch like that in a globular cluster, and that these stars have an ultraviolet excess as do most globular-cluster giants.We conclude therefore that this is a globular cluster with a modulus of m -M ^ 20 (assuming that the brightest giants in a globular cluster have M v --3).