Stacked signal in the nine Planck frequencies (30 to 857 GHz from upper to lower row). From left to right are displayed the Planck SZ detections identified with known clusters, the class1 high-reliability Planck SZ candidates, the class2 good-reliability Planck SZ candidates, and finally the class3 low-reliability SZ sources. The three lowest-frequency-channel images were convolved with a 10′ FWHM Gaussian kernel, whereas the remaining six highest-frequency-channel images were smoothed with a 7′ FWHM Gaussian kernel.