2004AJ....127.2382B

We derive fundamental parameters for the old, rich, open cluster NGC 1245 using BVI photometry from the MDM 1.3 m and 2.4 m telescopes. Based on detailed isochrone fitting, we find that NGC 1245 has a slightly subsolar metallicity, [Fe/H]=-0.05±0.03(statistical)±0.08(systematic) and an age of 1.04±0.02±0.09 Gyr. In contrast to previous studies, we find no evidence of significant differential reddening. We determine an extinction of A_V=0.68±0.02±0.09 mag and a distance modulus of (m-M)₀=12.27±0.02±0.12 mag, which corresponds to a distance of 2.8±0.2kpc. We derive a logarithmic mass function slope for the cluster of α=-3.12±0.27, where a Salpeter slope is α=-1.35. Fits to the radial surface density profile yield a core radius of r_c=3'.10±0'.52(2.57±0.47pc). NGC 1245 is highly relaxed and contains a strongly mass-segregated population. The mass function for the inner cluster has a very shallow slope, α=-0.56±0.28. In contrast, the outer periphery of the cluster is enriched with low-mass members and devoid of high-mass members out to the tidal radius, r_t=20' (16.5 pc). Based on the observed surface density profile and an extrapolated mass function, we derive a total cluster mass, M=1300±90±170M_☉.