XMM-Newton Users Handbook

3.2.1 X-ray point-spread function

The first critical parameter determining the quality of an X-ray mirror module is its ability to focus photons. Here lies one of XMM-Newton's major strong points: the core of its on-axis point-spread function (PSF) is narrow and varies little over a wide energy range (0.1-6 keV). Above 6 keV, the PSF becomes only slightly more energy dependent.


European Space Agency - XMM-Newton Science Operations Centre