Generates a dataset ancillaryfile.ds. The effective area, filter transmission and quantum efficiency curve are included in the ARF.
A point source located at the centre of the source region described in the data subspace within spectrum.ds is assumed. The effective area is calculated using the vignetting function at the central position on the detector of the point source. An encircled energy correction is applied (section 5.5). Corrections are applied for any CCD gaps or source region area falling outside the field-of-view or observing window but not for bad pixels or bad columns. These corrections will take into account the fraction of the point spread function (as a function of energy) which lies within the bad areas.