  One of the three cameras behind the X-ray telescopes on board XMM-Newton is
equipped with a pn CCD detector. Here the current status of the pn spectral
response calibration is summarized. Several parameters describing the spectral
response of the EPIC-pn detector show spatial dependencies. E.g. spectral
resolution and single- to double-pixel event ratios are functions of the charge
transfer losses and therefore depend on the distance to the read-out node of
the CCD (the RAWY detector coordinate).
