CoRoT red giant power spectra stacked into an image after sorting on the large separation. One line corresponds to one star. a) The first sorting is based on the large separation before any correction. b) The blurred aspect disappears once the correction has been performed and reveals the clear comb structure common to all red giants. The vertical lines at 23.2 μHz are the signature of the low-Earth orbit (Auvergne et al. 2009).