Deep and Wide Photometry of Two Open Clusters NGC 1245 and NGC 2506: CCD
  Observation and Physical Properties
  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'X82'
and 42'X81' for the two clusters, respectively, and reaches down to V = 23. We
derived the physical parameters using detailed theoretical isochrone fittings
using 2 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
(LFs) of the two clusters, which reach down to M_V = 10, and derive mass
functions (MFs) with slopes of Gamma = -1.29 for NGC 1245 and Gamma = -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.
