Probability density functions, f_2D(p,ψ | p₀,ψ₀,Σ_p), plotted for various values of ψ₀ (rows), spanning from − π/ 8 to 3π/ 8, and computed for four configurations of the covariance matrix (columns), parameterized by ε and ρ. The S/N on the intensity I is assumed to be infinite here. A true value of polarization p₀ = 0.1 has been chosen, and with S/N p₀/σ_p,G = 1. White crosses indicate the mean likelihood estimates of the PDF (). The contour levels are provided at 0.1, 1, 5, 10, 20, 50, 70, and 90% of the maximum of the distribution.