We present CCD UBVI photometry of the nearby , intermediate age open cluster NGC 6939 .
Using the synthetic Colour - Magnitude Diagrams technique we estimate the following parameters : age between 1.3 and 1.0 Gyr ( depending on whether or not overshooting is considered ) , reddening 0.34 \leq E ( B - V ) \leq 0.38 and distance modulus 11.3 \leq ( m - M ) _ { 0 } \leq 11.4 .