True azimuthal velocity V_φ (dashed histograms) computed from simulations of the Besançon model and the estimator (solid histograms) computed from the same simulations for the lines-of-sight of Sculptor (top), Sextans (middle) and Carina (bottom). For the lines-of-sight of Sextans and Carina, the velocity histograms have been decomposed into thin disc (red), thick disc (black) and halo (blue). The normalisation of each Galactic population is arbitrary, and has been chosen for reasons of clarity.