Transformations between 2MASS, SDSS and BVRI photometric systems: bridging the near infrared and optical

Authors

S. Bilir, Istanbul University Science Faculty, Department of Astronomy and Space Sciences, 34119, University-Istanbul, Turkey
S. Ak, Istanbul University Science Faculty, Department of Astronomy and Space Sciences, 34119, University-Istanbul, Turkey
S. Karaali, Beykent University, Faculty of Science and Letters, Department of Mathematics and Computer, Beykent 34398, Istanbul, Turkey
A. Cabrera-Lavers, Instituto de Astrofısica de Canarias, E-38205 La Laguna, Tenerife, Spain
T. S. Chonis, GTC Project Office, E-38205 La Laguna, Tenerife, Spain
C. Martin Gaskell, University of Nebraska-LincolnFollow

Date of this Version

11-1-2007

Comments

Online at arxiv.org. Copyright © by the authors.

Abstract

We present color transformations for the conversion of the 2MASS photometric system to the Johnson-Cousins UBV RI system and further into the SDSS ugriz system. We have taken SDSS gri magnitudes of stars measured with the 2.5-m telescope from SDSS Data Release 5 (DR5), and BV RI and JHK_s magnitudes from Stetson’s catalogue and Cutri et al. (2003), respectively. We matched thousands of stars in the three photometric systems by their coordinates and obtained a homogeneous sample of 825 stars by the following constraints, which are not used in previous transformations: 1) the data are de-reddened, 2) giants are omitted, and 3) the sample stars selected are of the highest quality. We give metallicity, population type, and transformations dependent on two colors. The transformations provide absolute magnitude and distance determinations which can be used in space density evaluations at short distances where some or all of the SDSS ugriz magnitudes are saturated. The combination of these densities with those evaluated at larger distances using SDSS ugriz photometry will supply accurate Galactic model parameters, particularly the local space densities for each population.