26 January 2001

This "Special Letters Issue" of the journal is exceptional for several reasons. Published henceforth four times a month, each edition of "Astronomy and Astrophysics" has normally featured a variety of papers on all aspects of astronomy and astrophysics. In 1999 and last year, it devoted three Special Letters Issues to the Very Large Telescope (VLT) in Chile but it has rarely devoted all its pages to a single space mission. The last time was in 1996 when it covered the first science results of ESA's infrared observatory, ISO.

"As editors in a competitive field and with XMM coming on line, we had wanted to get its first results into Astronomy and Astrophysics" explains Letters Editor Peter Schneider. "We also benefited from the driving force of Bernd Aschenbach, XMM-Newton's telescope scientist, based at the Max Planck Institute like ourselves. He and XMM-Newton project scientist Fred Jansen coordinated things, and it was the sheer number of papers submitted that led us to devote this issue entirely to XMM."

The high number of papers, with a large number of colour illustrations, is also quite a feat. "In the context of X-ray missions, it is unique to have a dedicated issue. It reflects first of all the many XMM observations that have already been carried out, and the great quality of the science data that is being obtained" explains XMM-Newton Project scientist Fred Jansen. "We must also thank all the authors and the referees who have allowed us to compile this special issue in such an extremely short time, just over six weeks. We are particularly pleased for everyone concerned because this A&A issue will ensure many citations in other publications."

The papers reflect the wide variety of celestial X-ray sources and astrophysical topics that have been covered both during the calibration and performance verification phase of XMM-Newton's science instruments and since routine observations started last summer. Much of this data has been featured in these web pages, at the 'First light' press event in Spain in February last year and at last December's 'XMM First science results' press conference in Paris.

"This A&A collection of papers constitutes on the one hand a solid reference source on the XMM-Newton spacecraft and instruments" says Peter Schneider. "On the science side, these results provide a first look at the exciting capabilities of the mission. From deep field imaging to stars, they cover the whole range of high-energy astrophysics. The observation numbers and the initial interpretations may change over time but the papers are motivating and will spur further research. I am sure that within one or two years we will be publishing another XMM special edition with even more impressive results."

"Astronomy and Astrophysics" was created in 1968 after the merger of several national astronomy journals. Distributed to nearly 1000 institutional and private subscribers, it is published by EDP Sciences in Paris.