First row, left: Shadowgram exposed for 20.48 s in the direction of the Galactic centre (4–120 keV). First row, right: corresponding weighted model used for cleaning. Second row: corresponding sky image in S/N in 20 s (left) and in 20 min obtained by the stacking of 64 different 20 s sky images. (right). Third row: same as above but the shadowgrams are cleaned prior to deconvolution. Last row: sources represented by black (respectively grey) circles are cleaned (respectively only masked in the sky image) in 20 s sky image (left) and 20 min sky image (right).