  In order to test the coordination and evaluate the overall performance of the
Gaia-FUN-SSO, an observation campaign on the Potentially Hazardous Asteroid (99
942) Apophis was conducted from 12/21/2012 to 5/2/2013 providing 2732 high
quality astrometric observations. We show that a consistent reduction of
astrometric campaigns with reliable stellar catalogs substantially improves the
quality of astrometric results. We present evidence that the new data will help
to reduce the orbit uncertainty of Apophis during its close approach in 2029.
