A European Space Agency's satellite, launched on 10 December 1999 and designed for the observation of → X-rays emitted by astronomical objects. The satellite carries three very advanced X-ray telescopes. The three corresponding European Photon Imaging Cameras (EPIC) are sensitive over the energy range 0.2 keV to 12 keV. Other instruments on-board are two reflection grating spectrometers which are sensitive below about 2 keV, and a 30 cm diameter → Ritchey-Chretien optical/UV telescope. The telescope moves in a highly elliptical orbit, traveling out to nearly one third of the distance to the Moon and enabling long, uninterrupted observations of faint → X-ray sources. The original mission lifetime was two years, it has now been extended for further observations until at least 2010. Among recent results obtained using XMM-Newton one can mention an intermediate-mass black hole of over 500 solar masses in the galaxy ESO 243-49 (Nature 460, 73, 2009) and broad line emission from iron K- and L-shell transitions in the active galaxy 1H 0707-495 (Nature 459, 540, 2009). See also → X-ray astronomy.
XMM, from "X-ray Multi-Mirror;" Newton, in honor of Sir Isaac Newton, → newton.