CCD UBV PHOTOMETRY OF THE YOUNG OPEN CLUSTER NGC-3766

NGC 3766 is a young open cluster, located in the Carina complex, which contains an unusually large number of Be stars. This fact makes it sp ecially interesting for providing observational constraints for the Be phenomenon. We have obtained UBV photometry for this cluster using a mosaic of CCD images centered around the cluster field, resulting in t he deepest color-magnitude diagram of NGC 3766 obtained so far. The an alysis of the photometric diagrams yielded a reddening of E(B - V) = 0 .20 +/- 0.10, a distance modulus of (m - M)(0) - 11.73 +/- 0.33 and an age of about 24 Myr. The luminosity function was derived by using the photometry of a nearby star field to remove field contamination from the cluster sample. The slope of the mass function was found to be Gam ma = - 1.41+/-0.08 in the range 2.5<M/M.<12.5, very close to the Salpe ter value (Gamma(Salpeter) = -1.35). There are some hints of mass segr egation in this cluster. (C) 1997 American Astronomical Society.