UBV and RV of red giants in NGC 2477

From 49 constant-velocity members we find a mean cluster velocity of +7.32+/-0.13km/s and confirm the membership of 76 of the stars. Among the cluster members, we identify 26 definite and 1 probable spectroscopic binaries and determine orbits for 13 of these systems, with periods ranging from 40 to 4578 days.

The binary frequency is thus rather high (27/76=36%). The observed internal radial velocity dispersion of the cluster, as determined from the single member stars, is 0.93km/s, corrected for the small average observational error of 0.22km/s. Fitting King-type models to the observed stellar density distribution and velocity dispersion, and assuming a distance of 1.25kpc, we find the core and tidal radii of NGC 2477 to be 1.8 and 8.1pc, respectively, and estimate that the mass of cluster stars down to V=17, corresponding to ~1M_{sun}_, is at least 5400 M_{sun}_.