BVRIJHK photometry and proper motion analysis of NGC 6253 and the surrounding field ^*,**

¹ Universitaets-Sternwarte der Ludwig-Maximilians-Universitaet, Scheinerstr.1, 81679 Muenchen, Germany e-mail: montalto@usm.uni-muenchen.de
² Max-Planck-Institute for Extraterrestrial Physics, Giessenbachstr., 85741 Garching bei Muenchen, Germany
³ Dipartimento di Astronomia, Università di Padova, Vicolo dell'Osservatorio 2, 35122 Padova, Italy
⁴ INAF – Osservatorio Astronomico di Padova, Vicolo dell' Osservatorio 5, 35122 Padova, Italy
⁵ Department of Physics and Astronomy, The Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218, USA
⁶ ESO, Casilla 19001, Santiago 19, Chile
⁷ Dipartimento di Fisica, Universitá di Trento, via Sommarive 14, 38123 Povo(TN), Italy

⁸ Laboratoire Cassiopée, Université de Nice Sophia-Antipolis, CNRS UMR 6202, Observatoire de la Côte d'Azur, France

Received: 30 July 2008
Accepted: 17 July 2009

Abstract

Context. We present a photometric and astrometric catalog of 187 963 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”33”. In this field, we provide CCD BVRI photometry. For a smaller region close to the cluster's 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 2.2 m telescope with its wide-field imager and the Anglo-Australian 3.9 m 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 cluster's fundamental parameters, deriving , , , , and . 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 ~20%-30% and identified 11 blue straggler candidates.