Press release


Publication of the first catalogue of X-ray sources detected
by the European satellite XMM-Newton

Strasbourg, April 7, 2003


CNRS/CEA/ULP/CNES Joint Press Release

The first issue of the catalogue of X-ray-emitting cosmic sources discovered by the European Space Agency’s (ESA’s) XMM-Newton satellite is being made public today and being put on-line via three sites: the Observatoire de Strasbourg (Université Louis Pasteur – CNRS), the Science Operations Center for the satellite in Vilspa (Spain), and the University of Leicester (England). Resulting from more than one year of observation, the catalogue lists several tens of thousands of X-ray-emitting stars and galaxies with sensitivity never attained before, thus pushing back the limits of our knowledge of the hottest celestial bodies in the Universe. The catalogue has been compiled by the Survey Science Centre (SSC) and will be a major resource for researchers in the field of high-energy astrophysics.

Coming on-line at the “Observatoire de Strasbourg”
The catalogue is now accessible to astronomers through a dedicated database which also makes it possible to consult the original data (“color” images of the sources, etc.), and connects the sources to archive data obtained at other wavelengths. By means of innovative computer science technology, this system optimizes browsing and makes highly complex requests possible. The project, funded by the “Centre national d'études spatiales” (CNES, French National Space Research Center), was realized by the Hautes Energies (High Energies) team from the Strasbourg Observatory, under the responsibility of C. Motch and L. Michel, and with support from the “Centre de données astronomiques de Strasbourg” (Strasbourg Astronomic Data Center).

Discovering the most faraway celestial bodies
Stars and galaxies can emit X-rays when they contain very hot regions at temperatures ranging from 1 million degrees to 100 million degrees. Such high temperatures are encountered in the coronas of most stars, where the magnetic fields can heat up the gas. Black holes such as those present in the centers of a large number of galaxies can also heat the matter that they swallow to very high temperatures. Since the Earth’s atmosphere blocks out X-rays, high-energy cosmic sources can be observed only in Space.

Offering unrivaled sensitivity, XMM-Newton made it possible to discover several tens of thousands of sources over its first 17 months in operation, as from March 2000. This catalogue is of major scientific interest because it gives access to the faintest and potentially the most distant sources known today. For each source, it proposes a very large number of details. It offers the possibility of constituting large samples with a view to performing statistical research or to seeking celestial bodies having unusual properties. The sources making up the catalogue are mostly stars and galaxies that emit X-rays.The catalogue was compiled by the Survey Science Centre (SSC) of the XMM-Newton satellite, on behalf of the ESA, and under the responsibility of J. Pye (University of Leicester). The SSC, directed by Dr. M. Watson from the University of Leicester, is an international collaboration bringing together several institutes in France, the United Kingdom, Germany, Spain, and Italy. The French institutes, supported by the CNES and taking part in the SSC are the “Observatoire Astronomique de Strasbourg” (Université Louis Pasteur - CNRS), the “Service d’astrophysique du CEA” (the Astrophysics Department of the French Atomic Energy Research Center) in Saclay, and the “Centre d’étude spatiale des rayonnements” or “center for space research on radiation” (CESR - CNRS) in Toulouse.

The major information in the catalogue
The catalogue contains the 33,000 new X-ray sources discovered in 585 observations. The work of the SSC is continuing and the catalogue is being enriched at a rate of from 25,000 to 30,000 sources every year. Within two years from now, it will have become the largest catalogue of cosmic X-ray sources ever published. The catalogue has been made possible thanks to numerous analysis programs developed by the collaboration as a whole. In addition to information coming from the cameras on the satellite, the catalogue also lists all of the known celestial objects with which each new X-ray source can be identified. This information, taken from astronomy catalogues in archives hosted at the Strasbourg Data Center, considerably extends the scientific potential of the catalogue. The SSC is also conducting several astronomic observation programs from optical telescopes with a view to clarifying the nature of the new X sources.

Further information about XMM-Newton
The ESA’s XMM-Newton satellite was launched on December 10, 1999 by the Ariane V launcher from the base of Kourou in French Guyana. Orbiting over an eccentric orbit whose period is 48 hours, it has been observing X-rays in the sky for more than 3 years now, for the considerable benefit of the world’s astrophysics community. For France, the CEA made a major contribution to calibrating the cameras equipping the main instruments of the satellite. The CESR also contributed to developing a part of the instrumentation. XMM-Newton carries the largest X mirrors ever put into orbit. For each observation, its three cameras look in the same direction and construct a deep image of a region of the sky of a size equivalent to that of the Full Moon. The great sensitivity of the instrument enables it, each time it is aimed in a new direction, to discover several tens of new X sources around a main target.

Public access to the catalogue
XMM-Newton catalogue:
Access reserved for professional astronomers
Observatoire de Strasbourg:
XMM-Newton – European Space Agency:

Researcher contacts:
Christian Motch, Observatoire de Strasbourg
Tel. +33 3 90 24 24 28
Didier Barret, CESR
Tel. +33 5 61 55 83 71
Jean Ballet, CEA
Tel. +33 1 69 08 70 17

Press Contact CNRS:
Martine Hasler
Tel: +33 1 44 96 46 35

Press department of CNES:
Tel: 33 1 44 76 76 87

Pascal Newton
Tel: +33 1 40 56 20 97

Université Louis Pasteur:
Agnès Villanueva
Tel: +33 3 90 24 11 35