Optimisation of the r hyper-parameter for a simple simulation with n_PSF = 0, γ₀ = 5, α₀ = 3 (and the same characteristics as in Table 1). Top: G(r) function (blue) and the minimum position r = 0.0467 (vertical black line). Middle: χ² evolution with r. Bottom: trace of the resolution matrix Tr R. The intersection with the black line gives the effective number of parameters fitted by data, here, 180.