Left panel: harmonic power excess for multipole order m from 1 to 17, as a function of different cluster-centric apertures. This is computed by averaging the multipolar moments of the galaxy distribution in Case 3. Error bars are the error on the mean computed from bootstrap re-sampling. Right panel: illustration of the different apertures from cluster centre ([0 − 1]R₅₀₀) to cluster outskirts ([9 − 10]R₅₀₀). The projected galaxy distribution around one given mock cluster (M₅₀₀ ∼ 1.3 × 10¹⁴ M_⊙ and z ∼ 0.44) integrated along a redshift slice (Δz = 0.06) centred on cluster redshift is represented with black points.