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17 February 2006

23/24 February: Gaia Conference at the University of Heidelberg

Centre for Astronomy of the University of Heidelberg in charge of coordination of core data analysis for the Gaia mission - Gaia to provide high-accuracy survey of a billion stars

Only a few days after final confirmation of the Gaia satellite project by the European Space Agency (ESA), an international scientific conference in preparation for the mission will be taking place at the University of Heidelberg on 23/24 February. The Centre for Astronomy of the University of Heidelberg is in charge of the coordination and preparation of core data analysis for the Gaia mission. Accordingly it has invited all the European scientists involved in the project to meet in Heidelberg.

Gaia builds on the Hipparcos mission of the 1980s, which provided a highly accurate catalogue of 100,000 stars and a less accurate picture of over 1 million stars. Here too, scientists from Heidelberg played a key role. The number of stars surveyed with a high degree of accuracy in the course of the Gaia census is much higher, in the vicinity of 1 billion. Accuracy will be about 50 times higher.

The central scientific aim of this astrometric satellite is to enhance our understanding of the structure, origins and evolution of our own galaxy, the Milky Way. Where, when and how did the stars originate and what do they give back to their environment when they die?

Gaia will almost certainly be the biggest discovery machine in the history of astronomy. The satellite is equipped to detect about a million asteroids and comets in our solar system, 30,000 planets outside our solar system, 50,000 failed stars (so-called brown dwarfs), hundreds of thousands of cooling remains of dead stars (so-called white dwarfs), 20,000 exploding stars (so-called supernovae), hundreds of thousands of remote active galaxies (so-called quasars) and millions of variable stars.

The Gaia satellite is being constructed by the Astrium company (Friedrichshafen/Germany and Toulouse/France) and is planned to start its trek with a Russian Sojus-Fregat rocket from the European spaceport at Kourou in French Guiana in late 2011. The cost of the project will total some 580 million euros. After take-off, Gaia will need about four months to reach a point where it will be held in position by the gravitational pull of the Earth and the Sun, about 1 million miles away on the night side of the Earth. This huge distance is necessary for observation to proceed with as little disturbance as possible. The accuracy requirements are extremely high. The most precise angular measurements undertaken by Gaia are designed to reach an accuracy of 15 micro-arc seconds, corresponding to approx. the diameter of a euro coin at a distance from the Earth to the Moon, or the diameter of a human hair at a distance of 700 kilometres.

For this angular measurement the Gaia telescopes look simultaneously at two different regions of the sky separated by an angle of 106°. As Gaia turns around its own axis every six hours it can scan a small ring of the sky every day. In the course of time the entire sky will be covered by means of slow inclination oriented to the direction of the Sun. Data capture is ensured by a mosaic of over 100 so-called CDD detectors surveying about 5,000 stars every second. Measuring accuracy will be achieved by the frequent repetition of the measurements taking place in the course of five years.

Ground control and all scientific operations are performed by the European Space Operations Centre ESOC in Darmstadt, in conjunction with the ESA ground station at Cebreros (Spain).

The Centre for Astronomy in Heidelberg is involved in the project in a variety of ways. It will not only coordinate the astrometric evaluation of the data but also employ intricate analysis procedures to verify whether measurement quality is actually living up to the aims the project has set itself. Only in this way can Gaia actually succeed in its mission, thus representing a major milestone in the progress of almost all areas of astrophysics.

For an artist's impression of Gaia (copyright ESA) go to www.ari.uni-heidelberg.de/gaia/gallery/GR/gr0283-01.artistic-Gaia-Galaxy-large.jpg

Please address any inquiries to:
Dr. Stefan Jordan,
University of Heidelberg,
Centre for Astronomy,
Mönchhofstr. 12-14
D-69120 Heidelberg
phone: 06221/541842
jordan@ari.uni-heidelberg.de

Head of the Gaia research group at the Centre for Astronomy, Heidelberg:
Dr. Ulrich Bastian,
Centre for Astronomy
phone: 06221/541852

Scientists involved in the Gaia project at the Centre for Astronomy:
Dr. Hans Bernstein, Dr. Michael Biermann, Dr. Sonja Hirte, Dr. Stefan Jordan, Dr. Helmut Lenhardt, plus visiting international scientists and the non-scientific staff of the institute.

Director of the Centre for Astronomy, Heidelberg:
Prof. Dr. Joachim Wambsganß
phone: 06221/541801

Journalists should address their inquiries to
Dr. Michael Schwarz
Press Officer of the University of Heidelberg
phone: 06221/542310, fax: 54317
michael.schwarz@rektorat.uni-heidelberg.de
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