NGC 1245 - an intermediate age open cluster

Abstract

The B,V CCD photometry of 916 stars in the field of the high galactic latitude intermediate age open cluster NGC 1245 is presented. The cluster parameters were estimated with the help of V vs (B-V) colour-magnitude diagram (CMD). After correcting for intra-cluster reddening, the mean reddening towards the cluster was found to be 0.29$\pm$0.05 mag, with a distance modulus of 12.4$\pm$0.3 mag. The cluster is found to be located at a distance of 3 Kpc. The isochrone fits using Girardi et al. (2000) isochrones to the cluster CMD estimated an age of 890$\pm$100 Myr. The synthetic CMDs obtained using Girardi et al. (2000) models incorporating photometric errors and 10% binary stars estimated an age of 1 Gyr for the cluster. The luminosity function (LF) of the main-sequence shows dips, which might arise due to some known gaps in the main-sequence, including the Bohm-Vitense gap. The LF and the integrated LF computed from the observed CMD is compared with those computed from the sythetic CMDs for five values of mass function slope. The estimation of the slope of the present day mass function indicates a flatter value compared to the Salpeter value, though an accurate estimation is not possible due to the large dips found in the LF. The apparent paucity of stars seen near the cluster center is estimated to have a statistical significance of 2 sigma.