pnCCDs on XMM-Newton: 42 months in orbit

Abstract XMM-Newton—a cornerstone mission of the European Space Agency's Horizon 2000 programme—was launched on December 10, 1999 into orbit. Since March 2000 more than 2000 scientific observations were made. An example will be shown. The X-ray pnCCD camera on EPIC is operating since then without severe problems. We will report about the system performance as a function of time, with special emphasis on the effect of radiation damage in orbit. Up to now the spectroscopic and imaging performance of the pnCCD camera system is stable with time, even at the lowest energies most sensitive to degradation. The deviations of the detector response compared to the prelaunch performance over the 3.5 years is below 0.5%. One year after launch, the pnCCD X-ray camera was hit by a micrometeoroid, damaging 35 pixels spread over the entire field of view. Details of the impact of the pnCCD with a cosmic dust particle will be given. X-ray fluorescence photons, stimulated by charged particles, constitute a significant part of the instrument background. Possible improvements for future missions will be discussed.