BVI CCD photometry of Berkeley 17

This study reveals Be 17 to have a metallicity -0.30<=[Fe/H]<=0.00; a reddening 0.52<=E(B-V)<=0.68 or 0.61<=E(V-I)<=0.71; a distance modulus, (m-M)_0_=12.15+/-0.10, corresponding to a distance of 2.7+/-0.1kpc; a diameter of ~10pc; a minimum mass of 400 Msun; and an age of 10-13Gyr.

With an adopted age of 12(+1)(-2)Gyr, these results suggest that Be 17 is indeed the oldest open cluster yet discovered. The inferred old age for Be 17 indicates that the cluster is an important one for studies of the differences between open and globular clusters, the transition from the halo/thick disk to the thin disk of the Galaxy, and even for establishing the minimum age of the universe.