CCD Washington photometry of the intermediate age open cluster Tombaugh 1

Abstract

CCD Washington CT1 photometry in the field of the open cluster Tombaugh 1 is presented. Based on the best fits of isochrones computed by the Geneva group for Z = 0.008 to the (T1,C-T1) diagram, we derive reddening, distance and age. A metal abundance [Fe/H] = -0.30 +/- 0.25 was also estimated through the Standard Giant Branch method. Both the position of Tombaugh 1 in the Galaxy as well as its metal content are compatible with the existence of a radial abundance gradient in the galactic disc.