XMM-Newton is ESA active X-ray observatory, launched on 10 December 1999 and operating in a 48-hour highly elliptical Earth orbit for long, uninterrupted observations of the high-energy Universe.
XMM-Newton is ESA active X-ray observatory, launched on 10 December 1999 and operating in a 48-hour highly elliptical Earth orbit for long, uninterrupted observations of the high-energy Universe.