Welcome to the web site of the Gaia Classification Working Group on Identification, Classification and Parametrization, also known as ICAP.

When launched in 2011, the Gaia satellite will undertake a very detailed and extensive astrometric and photometric study of our Galaxy with the primary goal to determine its formation, composition and evolution. Gaia will observe every object in the sky brighter than V=20, that is some 1 billion (10^9) stars, galaxies, quasars and solar system objects, so there are also numerous supplementary science projects ranging from exo-solar planets to fundamental physics. High precision astrometry will be obtained for every object, yielding accurate positions, parallaxes and proper motions. Radial velocities will also be obtained (down to about V=18), thus producing a 6D phase space catalogue (three spatial and three velocity co-ordinates) for a significant fraction of our Galaxy. Photometry will be obtained of every object in some 19 medium and broad band optical filters tens of times over the course of the five year mission. For more information on the mission and its science see this article.

The goal of this working group (ICAP) is to develop the necessary methods to classify all of the objects observed and to determine meaningful astrophysical parameters (such as stellar effective temperatures, compositions, radii and so forth). This will make use not only of the multiband photometry, but also the parallaxes, the proper motions (e.g. for QSO detection), the radial velocity spectrum (yielding much additional information on bright targets) and variability data. More information can be found in this article.

1 January 2006: Transition to the Data Processing consortium

As of 1 January 2006, this working group, along with all of the other Gaia working groups, has been dissolved. Now that Gaia is entering the detailed design and construction phase, the tasks of the working groups have been taken over by the Gaia Data Processing and Analysis Consortium. This comprises nine "Coordination Units". The ICAP activities are now undertaken by CU8: Astrophysical Parameters under the leadership of Coryn Bailer-Jones (deputy Frederic Thevenin, Nice). All online information is now managed via the tools as ESA (Wiki, Livelink, Subversion etc.). Most of this is password restricted, but some can be accessed via the main Gaia web site.