Proper motions and membership probabilities of stars in the region of
  open cluster NGC 3766
  Relative proper motions and cluster membership probabilities have been
derived for ~ 2500 stars in the field of the open star cluster NGC 3766. The
cluster has been observed in $B$ and $V$ broadband filters at two epochs
separated by ~ 6 years using a wide-field imager mounted on the WFI@ESO2.2m
telescope. All CCD frames were reduced using the astrometric techniques
described in Anderson et al. (2006). The proper motion r.m.s. error for stars
brighter than $V$ ~ 15 mag is 2.0 mas/yr but it gradually increases up to ~4
mas/yr at $V$ ~20 mag. Using proper motion data, membership probabilities have
been derived for the stars in the region of the cluster. They indicate that
three Be and one Ap stars are member of the cluster. The reddening
$E(B-V)=0.22\pm0.05$ mag, a distance 2.5$\pm$0.5 kpc and an age of ~ 20 Myr are
derived using stars of $P_{\mu}>70%$. Mass function slope $x=1.60\pm0.10$ is
derived for the cluster and cluster was found to be dynamically relaxed.
Finally, we provide positions, calibrated $B$ and $V$ magnitudes, relative
proper motions and membership probabilities for the stars in the field of NGC
3766. We have produced a catalog that is electronically available to the
astronomical community.
