  We have obtained BVI CCD imaging of Berkeley 17, an anticentre open cluster
that competes with NGC 6791 as the oldest known open cluster. Using the
synthetic colour magnitude diagrams (CMD) technique with three sets of
evolutionary tracks we have determined that its age is 8.5 - 9.0 Gyr, it
distance modulus is (m-M)_0 = 12.2, with a reddening of E(B-V) = 0.62 - 0.60.
Differential reddening, if present, is at the 5 % level. All these values have
been obtained using models with metallicity about half of solar (Z=0.008 or
Z=0.01 depending on the stellar evolution tracks), which allows us to reproduce
the features of the cluster CMD better than other metallicities. Finally, from
the analysis of a nearby comparison field we think to have intercepted a
portion of the disrupting Canis Major dwarf galaxy.
