Overview and stellar statistics of the expected Gaia Catalogue using the
  Gaia Object Generator
  Aims: An effort has been undertaken to simulate the expected Gaia Catalogue,
including the effect of observational errors. A statistical analysis of this
simulated Gaia data is performed in order to better understand what can be
obtained from the Gaia astrometric mission. This catalogue is used in order to
investigate the potential yield in astrometric, photometric and spectroscopic
information, and the extent and effect of observational errors on the true Gaia
Catalogue. This article is a follow-up to Robin et. al. (2012), where the
expected Gaia Catalogue content was reviewed but without the simulation of
observational errors. Methods: The Gaia Object Generator (GOG) catalogue is
analysed using the Gaia Analysis Tool (GAT), producing a number of statistics
on the catalogue. Results: A simulated catalogue of one billion objects is
presented, with detailed information on the 523 million individual single stars
it contains. Detailed information is provided for the expected errors in
parallax, position, proper motion, radial velocity, photometry in the four Gaia
bands, and physical parameter determination including temperature, metallicity
and line of sight extinction.
