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تسجيل مستخدم جديدBVRIJHK photometry and proper motion analysis of NGC 6253 and the surrounding field
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Context. We present a photometric and astrometric catalog of 187963 stars located in the field around the old super-metal-rich Galactic open cluster NGC 6253. The total field-of-view covered by the catalog is 34 x 33. In this field, we provide CCD BVRI photometry. For a smaller region close to the clusters center, we also provide near-infrared JHK photometry. Aims. We analyze the properties of NGC 6253 by using our new photometric data and astrometric membership. Methods. In June 2004, we targeted the cluster during a 10 day multi-site campaign, which involved the MPG/ESO 2.2m telescope with its wide-field imager and the Anglo-Australian 3.9m telescope, equipped with the IRIS2 near-infrared imager. Archival CCD images of NGC 6253 were used to derive relative proper motions and to calculate the cluster membership probabilities. Results. We have refined the clusters fundamental parameters, deriving (V_0-M_v)=11.15, E(B - V)=0.15, E(V - I)=0.25, E(V - J)=0.50, and E(V - H)=0.55. The color excess ratios obtained using both the optical and near infrared colors indicate a normal reddening law in the direction of NGC 6253. The age of NGC 6253 at 3.5 Gyr, determined from our best-fitting isochrone appears to be slightly older than the previous estimates. Finally, we estimated the binary fraction among the cluster members to be sim20%-30% and identified 11 blue straggler candidates.
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