I spy with my little eye: XMM-Newton in the sky!
21 Jun 2000After being detected using telescopes equipped with electronic CCD imaging cameras, ESA's X-ray space observatory has been sighted visually for the very first time.
This exploit, using a commercially available 20cm Schmidt-Cassegrain telescope, was achieved by a French amateur astronomer, more accustomed to tracking down asteroids. Gerard Faure, an accountant living in the Vercors pre-Alpine region, is rated one of the most active visual observers of asteroids in the world, having seen nearly 1400 asteroids. He manages an asteroid working group with the co-ordinators of the Minor Planet Section of the Association of Lunar and Planetary Observers. "I also belong to the 'Alphonse Pouplier' Internet network for all those who want to observe artificial satellites" explains Faure. "Our interest in XMM-Newton was triggered by the previous detections by Gordon Garradd in Australia, then by Stefano Sposetti in Switzerland. They used CCD cameras. Why couldn't we see it visually?" Reports of unsuccessful attempts accumulated over two months so Faure took up the challenge, knowing full well that very precise, up-to-date ephemeris were indispensable. He called upon the help of both Belgian expert Alphonse Pouplier, and the retired ESA staffer Bruno Tilgner who had assisted Sposetti in April.
Faure tried three times, twice in May, once on 3 June, but unsuccessfully. Once again on the evening of 9 June, after sleeping a couple of hours at his privileged viewing site situated an altitude of 1170m, he was behind his 20 cm Celestron 8 ready to spot the satellite. The telescope had a 25mm eyepiece with a x80 magnification, the field of view was 37.5'.
"The suspense didn't last long. Shortly after 2am local time, coming down from the south-west, not far from Alpha Ophiuchus, there was XMM-Newton slightly south of the predicted trajectory on my charts! It was particularly bright, at magnitude 9.2, much more than I had expected. It was then at a distance of 8163 kilometres, practically at perigee. I hastily noted the time, moved slightly to follow it a couple of degrees and to compare its brightness with nearby stars. I only saw it for some 20 seconds. Enough to say 'Hurrah'".
After attempting to see the satellite in the Eagle constellation, Faure was rewarded a second time half an hour later as it passed through Pegasus. The eyepiece used this time was 12.5mm, with a x160 magnification and a 18.5' field. XMM-Newton was again slightly to the south of the predicted track, with a 8.4 magnitude.
"This brightness convinces me that on a really dark night, XMM should be visible even with 11x80 binoculars when it passes perigee."
XMM-Newton is an ESA Science mission, launched on 10 December 1999