XMM-Newton prepares second round of observations
12 November 2001The world's astronomers are once again queuing up to use XMM-Newton. In fact ESA's X-ray observatory appears to be even more attractive second time around. The response to the second call for proposals has resulted in 870 submissions - more than for the first call prior to its launch in 1999.
The second Announcement of Opportunity (AO-2) was issued at the end of August. It covers observations to be carried out from mid-2002 to mid-2003. Analysis of the time needed for these new proposals is underway, but it is clear that they represent a 9.5 times oversubscription. In other words, if all requests were to be fulfilled, XMM-Newton would have to assign the next 10 years to performing these observations! The first call for proposals in 1998 had been oversubscribed 6.8 times.
Computers at the XMM-Newton VILSPA Science Operations Centre near Madrid had to cope with a last minute rush as the October 26 deadline approached. More than half the submissions arrived in the last 48 hours!
A selection process by peer review will now begin. The submissions must be whittled down to a combination of the best proposals which can be accommodated in the time allocated for AO-2 observations. The members of the AO-2 Time Allocation Committee will be examining all the submissions at meetings in December and January. Final selection will be in March 2002.
The proposals cover 7 categories of X-ray celestial objects. The category concerning Active Galactic Nuclei, Quasars and BL-Lac Objects (bright sources with no emission lines which can be extremely variable) represents the largest group, with 216 proposed observations. White Dwarf Binaries, Neutron Star Binaries, Cataclysmic Variables and Black Holes as a category is second, with 169 proposals.
The AO-2 'Top Seven' continues with Galaxies and Groups of Galaxies (115); Clusters of Galaxies and Superclusters (113); Supernovae and their remnants, Diffuse (galactic) Emission and Isolated Neutron Stars (109); Stars, White Dwarfs and Solar System (104); and 44 submissions address the issue of X-ray background emission and surveys, such as those of the Galactic Plane.
This second announcement of opportunity also offered a new possibility of combined observations, using both XMM-Newton and NASA's Chandra observatory, and ground-based telescopes belonging to the European Southern Observatory.
"We have broken new ground, soliciting proposals for joint observations with Chandra and with ESO," comments Fred Jansen, XMM-Newton project scientist. "The number of submissions in this new framework is fairly low, but the response clearly shows the advantages of this new possibility."
"We have received, for example, proposals to study the variability of certain X-ray sources using both XMM-Newton's Reflection Grating Spectrometer which covers the lower energy band with a great collecting power, and with Chandra's own grating spectrometers at higher energies and with a higher resolution. I think such observations could provide some spectacular science."
Submissions for this second round of observations come from principal investigators in 23 different countries, and 35 countries when all their co-investigators are included.
In an interview, XMM-Newton project scientist Dr. Fred Jansen reviews the mission so far, the response to AO-2 and explains the combined operations with NASA's Chandra and ESO ground observatories. See also the link on the right hand side: Living up to expectations and looking towards the future; an interview with Fred Jansen.