The data sample used for the validation contains a list of 14 124
Solar System Objects (SSOs), 290 704 transits and 2 005, 683 observations at CCD level.
The objects are all numbered asteroids and they are a valid representation of the whole population of SSOs, namely near-Earth and main-belt asteroids (NEAs and MBAs respectively), Jupiter trojans and transneptunian objects (TNOs).
To assess the quality of the astrometry we have our own external validation tool, which mainly consists in an orbit determination procedure that fits an orbit (taking as first guess the best known orbits) using only the available 22 months of Gaia observations.