Characterising Open Clusters in the solar neighbourhood with the
  Tycho-Gaia Astrometric Solution
  The Tycho-Gaia Astrometric Solution (TGAS) subset of the first Gaia catalogue
contains an unprecedented sample of proper motions and parallaxes for two
million stars brighter than G~12 mag. We take advantage of the full astrometric
solution available for those stars to identify the members of known open
clusters and compute mean cluster parameters using either TGAS or UCAC4 proper
motions, and TGAS parallaxes. We apply an unsupervised membership assignment
procedure to select high probability cluster members, we use a Bayesian/MCMC
technique to fit stellar isochrones to the observed 2MASS JHK$_s$ magnitudes of
the member stars and derive cluster parameters (age, metallicity, extinction,
distance modulus), and we combine TGAS data with spectroscopic radial
velocities to compute full Galactic orbits. We obtain mean astrometric
parameters (proper motions and parallaxes) for 128 clusters closer than about 2
kpc, and cluster parameters from isochrone fitting for 26 of them located
inside 1 kpc from the Sun. We show the orbital parameters obtained from
integrating 36 orbits in a Galactic potential.
