SIMBAD references

We report on a deep CCD UBV(RI)_Cphotometric survey in the region of the young open cluster Markarian 50. The new photometric data allow us to extend the cluster membership down to V~ 17.5, about 2 mag deeper than any previous investigation. On the basis of these data we derive a distance d= 3460±350 pc (V_O-M_V= 12.7±0.2), which turns out to be only slightly lower than previous estimates. The cluster presents differential reddening, with E(B-V) values ranging from 0.69 to 1.1. The brightest member (HD 219460) is a double star, which we separate photometrically for the first time, providing individual magnitudes and colours for each component. One of them is a Wolf-Rayet (WR) star and, according to evolutionary models, the mass of its progenitor should be greater than ∼20 M_☉. The age obtained for the cluster is 7.5±2 Myr and the mass function for the most massive stars (M > 1 M_☉) presents a slope x~ 1.0.