Histogram of the values of 5000 random catalogues (each having N_c = 1526) on simulated lensed skies with added 2D-ILC noise. The mean and rms for the 5000 mock catalogues are 1.07 × 10⁻⁵ and 2.13 × 10⁻⁷, respectively. The vertical dashed lines indicate the values at the MCXC cluster positions before and after the cluster-lensing effect is added; the values are 1.047 × 10⁻⁵ before (purple line) and 1.061 × 10⁻⁵ after (red line).