Final source detection is done through map mode box detection (eboxdetect in map mode) and maximum likelihood PSF fitting (emldetect) using simultaneously the input images of all pointings, cameras and energy bands. Note that the computer memory needed is proportional to the number of input images and the number of pixels in each input image. It is recommended therefore not to combine images which are not overlapping in this procedure.
Even a mosaicking observation with say 25 pointings is not necessarily processed in one step, but rather grouping overlapping exposures, and repeating the exercise even using same inputs partially in several runs.
