Platais, I., Cudworth, K. M., Kozhurina-Platais, V., McLaughlin, D. E., Meibom, S. and Veillet, C.
Abstract
We present comprehensive cluster membership and g'r' photometry of the prototypical old, metal-rich Galactic star cluster NGC 6791. The proper-motion catalog contains 58,901 objects down to g'~ 24, limited to a circular area of radius 30'. The highest precision of the proper motions is 0.08 mas yr-1. Our proper motions confirm cluster membership of all main and also some rare constituents of NGC 6791. The total number of probable cluster members down to g' = 22 (MV ~ 8) is ~4800, corresponding to M tot ? 5000 M sun. New findings include an extended horizontal branch in this cluster. The angular radius of NGC 6791 is at least 15' (the effective radius is Rh ~= 4farcm4 while the tidal radius is rt ~= 23'). The luminosity function of the cluster peaks at M_{g^{\prime }}\sim 4.5 and then steadily declines toward fainter magnitudes. Our data provide evidence that differential reddening may not be ignored in NGC 6791.
