The likelihood is non-Gaussian. Upper row: varying the power spectrum coefficients for different multipole values, we plot slices of the likelihood function (solid lines) at low (ℓ = 200, left panel), intermediate (ℓ = 500, middle panel), and high multipoles (ℓ = 800, right panel). We also show the best fitting Gaussian distributions (dashed lines). Lower row: the absolute residual between the likelihood function and its Gaussian fit is of the order of several percent.