Distribution functions of relative orientations for the Gaussian model with σ_M = 33°. The distributions show the effects of projection onto the plane of the sky of the 3D relative orientations between V_M and V_M0. The curves refer to four different configurations depending on η, the fraction of 3D perpendicular orientations between the two vectors. For the blue curve, η = 0. For the pink, red, and green curves, η is 0.5, 0.7 and 0.9, respectively.