Marginalised posteriors p(M_p|x) for the planet mass given the 16 au gap in HD 142666 with no additional constraint on α (green histogram), and setting Gaussian priors for log α centred at −3 (dark red histogram) or −4 (orange histogram), each with a standard deviation of 0.1. Means mu and standard deviations σ of the shown distributions are: μ=−3.82, σ=0.11 (no constraint on α); μ=−3.60; σ=0.11 (α = 10⁻³); and μ=−3.96, σ=0.08(α = 10⁻⁴).