Illustration for two pulsars of the contributions to the integrand of the likelihood L_maxw(σ) (Eq. (19)) of the separate factors f_D(D)g_D(ϖ′ | D) (top graphs; Eqs. (1) and (4)), I_α and I_δ (middle graphs). Each curve has been normalized separately to maximum unity. I_α and I_δ are shown for for three values σ of the Maxwellian (Eq. (14)). The lower graphs show the integrand of the likelihood L_maxw(σ) for three values of σ, as a function of distance, normalized to the highest maximum of the three. The measurements of PSR J0034−0721 (left) favour a low value of σ. Those of PSR B1508+55 (right) require a high value of σ, and the integrands for σ = 50 and 100 km s^-1 are indistinguishable from zero in this graph.