UBGVRI photometry for the open cluster NGC 2506 is presented .
From comparison of the observed colour-magnitude diagrams with simulations based on stellar evolutionary models we derive in a self consistent way reddening , distance , and age of the cluster : E ( B - V ) =0-0.07 , ( m-M ) _ { 0 } = 12.6 \pm 0.1 , \tau = 1.5-2.2 Gyr .
The cluster shows a well definite secondary sequence , suggesting that binary systems constitute \lower 2.58 pt \hbox { $ \sim$ } \kern - 7.75 pt \raise 2.795 pt \hbox { $ > $ } 20 % of the cluster members visible in the colour-magnitude diagram .