SIMBAD references

Galactic open clusters provide an abundant sample of stellar aggregates of various sizes, ages and metal abundances, apt to constitute a template for comparison with star systems in other galaxies. In this paper we present and discuss a standard methodology to synthesize U,B,V fluxes and colours, and apply it to a set of 138 open clusters.
Result. are compared with previous ones available in the literature. We were able to calibrate a mass-luminosity relation by which we evaluated the mass of ∼400 open clusters, leading to a well defined present-day mass function. The number-complete sample of galactic open clusters presented in Battinelli & Capuzzo-Dolcetta (1991) is enlarged of a 15%.