CCD Photometry of Galactic Globular Clusters V. NGC 2808

Abstract

We present a deep color magnitude diagram for the galactic globular cluster NGC 2808 (C0911-646), reaching 3 magnitudes below the main sequence turnoff. A set of local photometric standards are provided, and the mean cluster reddening and metallicity are constrained using several photometric techniques. The unusual horizontal branch morphology discovered by Sosin et al. (1997, ApJ, 480, L35) is confirmed. No significant radial population gradients are identified to within the limits of the data. We investigate the redwards color spread on the main sequemce found by Ferraro et al. (1997, A&A, 327, 598) in a field centered 6.3 arcmin from the cluster center, attributed to binaries. We conclude that the spread is in the most part due to a non-Gaussian distribution of photometric errors about the main sequence ridgeline.