2012MNRAS.425.1567L

We have conducted VI CCD photometry of the two open clusters NGC 1245 and NGC 2506 using the CFH12K CCD camera. Our photometry covers a sky area of 84 x 82 and 42 x 81arcmin² for the two clusters, respectively, and reaches down to V ≈ 23. We derived the physical parameters using detailed theoretical isochrone fittings using χ² minimization. The derived cluster parameters are E(B - V) = 0.24±0.05 and 0.03±0.04, (V - M_V)₀= 12.25±0.12 and 12.47 ±0.08, age(Gyr) = 1.08±0.09 and 2.31±0.16, and [Fe/H] = -0.08 ±0.06 and -0.24±0.06, respectively, for NGC 1245 and NGC 2506. We present the luminosity functions of the two clusters, which reach down to M_V ≈ 10, and derive mass functions with slopes of Γ = -1.29 for NGC 1245 and Γ = -1.26 for NGC 2506. The slopes are slightly shallower than that of the solar neighbourhood, implying the existence of dynamical evolution that drives the evaporation of the low-mass stars in the clusters.