  We obtain full information on the orbital parameters by combining radial
velocity and astrometric measurements by means of Bayesian inference. We sample
the parameter probability densities of orbital model parameters with a Markov
chain Monte Carlo (McMC) method in simulated observational scenarios to test
the detectability of planets with orbital periods longer than the observational
timelines. We show that, when fitting model parameters simultaneously to
measurements from both sources, it is possible to extract much more information
from the measurements than when using either source alone. We demonstrate this
by studying the orbit of recently found extra-solar planet HD 154345 b.
