UBVRI CCD photometry of the old open cluster NGC 6253
Abstract
We present UBVRI photometry for the old open cluster NGC 6253. From comparison of the observed colour-magnitude diagrams with simulations based on stellar evolutionary models we derive in a self consistent way reddening, distance, and age of the cluster: E(B-V) = 0.23-0.32, (m-M)0 = 10.90.1, metallicity roughly double than solar, and age 3 Gyr. The cluster has a binary sequence, discernible even through the field contamination, suggesting that about 1/3 of the cluster members belong to binary, or multiple, systems.
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