Gaia is the space astrometry mission of the European Space Agency to be launched in 2011.  Over a period of five years, it aims at
observing 1.2 billion stars for which accurate position and motion (as well as some astrophysical parameters) will measured.  IAA
hosts several components of the coordination unit (CU) 4 of the Gaia Data Processing and Analysis Consortium.  That CU is built
upon several Development Units (DU) spread all over Europe.  Those DU are in charge of writing, testing, ... the codes that will
become the Gaia data reduction pipeline later on.  There are thus key entities in the success of the mission. Two of these DU are
based at IAA.  One is composed of two postdocs and one computer scientist who are responsible for the codes for eclipsing binaries
(one star orbiting an other and sometime blocking the light from the latter).  That DU is essentially founded through an ESA Prodex
grant.  The second DU is in charge of the astrometric and resolved binaries.  The former correspond to objects whose duplicity is
noted through a careful inspection of their motion whereas the latter clearly appear as double on the detector.  That second DU
is founded by FNRS and the European Commission (Research and Training Network).  The manager of the entire CU4 belongs to IAA.