This task takes the EPIC images in the input list of images, divides them by the images in the input list of `exposure maps', rebins the resulting images to a user-specified bin size and plots the corresponding intensity (count-rate) histograms (number of image bins containing a countrate within a certain interval) to a single PostScript file. The last bin includes all rebinned pixels brighter than the maximum value shown in the x-axis and it is marked with an arrow.
The rationale for developping this task is to allow the user to estimate quickly the intensity background in a number of bands, and to assess the significance of the detection of faint sources. To achieve this, it is necessary that the input images are in a useful set of energy bands (such as the default EPIC IMAGING energy bands), and that the images listed in the parameter exposuresets are their corresponding exposure maps.
Furthermore, if the user-selected bin size binsize is the size of the point spread function, the number of pixels above a given countrate is roughly the number of sources with fluxes above that countrate.
