uvby-Hβ CCD photometry of NGC 1817 and NGC 1807

Abstract

We have investigated the area of two NGC entries, NGC 1817 and NGC 1807, with deep CCD photometry in the uvby–Hβ intermediate-band system. The photometric analysis of a selected sample of stars of the open cluster NGC 1817 yields a reddening value of E(b − y) = 0.19 ± 0.05, a distance modulus of V0 − MV = 10.9 ± 0.6, a metallicity of [Fe/H] = −0.34 ± 0.26 and an age of log t = 9.05 ± 0.05. Our measurements allow us to confirm that NGC 1807 is not a physical cluster.