CCD UBVRI Photometry of 4 open clusters

The sample consists of about 2000 stars reaching down to V=20mag. The interstellar extinction across the face of the imaged cluster regions seems to be uniform with average values of E(B-V)=0.31, 0.34 and 0.22mag for NGC 4103, NGC 5662 and NGC 6087 respectively.

The distances to the clusters NGC 3228, NGC 4103, NGC 5662 and NGC 6087 have been estimated as 0.5+/-0.05, 2.0+/-0.3, 0.8+/-0.1 and 1.0+/-0.1kpc respectively, while the corresponding ages estimated from the theoretical stellar evolutionary isochrones fitted to the bright proper motion cluster members are ~100, 30, 80 and 65Myr respectively. Present data are consistent with the membership of the Cepheid variable V Cen to NGC 5662 and of S Norm to NGC 6087.