Signal-to-noise ratio profiles for all the clusters. The net count rates are computed from the best-fit model of the soft-band image (see Sect. 4.1 for more details). For each cluster, the S/N as a function of radius is shown as a curve color-coded by its maximum value. The maximum S/N and the corresponding radii for all clusters are marked with blue dots. Clusters with maximum S/N lower than 3 are plotted in dark gray. The histogram in the upper left panel shows the distribution of the maximum S/N, only considering clusters with maximum S/N higher than 3, in order to remove the contamination from low-significance clusters.