The EPIC and RGS response matrices generated by the SAS tasks `arfgen` and `rmfgen', and `rgsrmfgen' respectively, already include the effective area of the telescopes together with the vignetting or the diffraction efficiency of the gratings, the transmissions of the filters and the quantum efficiency of the detectors.
Depending on the selected source extraction window in EPIC and on the spectrum extraction region in RGS, the SAS tasks `rmfgen' and `rgsrmfgen' apply additional corrections for count losses out of these windows. In the case of EPIC, this is performed using encircled energy fractions of the point spread function calibrated for the different telescopes. The illustration of telescopes effective area (Figs. 11 and 12) and encircled energy (Figs. 5, 6 and 7) functions are provided in this section only for general information. These graphs should not be used for the purpose of effective area correction. This is normally done by the SAS tasks by the generation of the RGS and EPIC instrument response matrices. The user could produce tabulated values of the telescope effective area and encircled energy fraction using the SAS task 'calview'. Should this be the case, the XMM-Newton SAS Users Guide should be consulted.
European Space Agency - XMM-Newton Science Operations Centre