PHOTOELECTRIC UBV AND DDO PHOTOMETRY IN THE ANOMALOUS GLOBULAR CLUSTER NGC 2808.

Results from a new program of photoelectric UBV and DDO photometry in the uniquely anomalous globular cluster NGC 2808 are reported. The combined new data confirm that NGC 2808 is moderately metal-rich ( ( U - B) 0.14, [Fe/H] (DDO) -0.8), with a predominantly red horizontal branch and essentially no RR Lyrae stars. The existence of the isolated group of extreme blue stars ((B - v)o < 0.0) on the horizontal branch is also confirmed, with HB stars of intermediate color (0.0 (B - v)o 0.4) almost completely absent. The most plausible interpretation seems to remain the one in which the red and blue groups of H-B stars are segregated in mass by 0. ). 10 9.) .. Key words: globular cluster-photometry-horizontal branch-element abundances