XMM-Newton Science Analysis System


eregionanalyse (especget-1.57) [22.0.0-9173c7d25-20250127]

Encircled energy factor

The fraction of counts contained within the source region assuming a point source located at the centre of the region. The PSF used to calculate the fraction is defined by the psfmodel parameter at a fixed photon energy of 1.5 keV. This is currently only implemented for circular source regions, other shapes will give the wrong factor.