Top: azimuthal profile of tangential velocity at R = 1 kpc. Colored symbols are the velocities inferred by the tangent-point method at a similar radius for the two quadrants. The horizontal dashed line is the azimuthal average of the velocity profile, hence the velocity of the rotation curve at R = 1 kpc. The zero azimuth corresponds to the direction of the Sun. Bottom: profile of radial velocity v_R, locally given at the positions of the tangent points. Each value is not an azimuthal average from the radial velocity field at each radius. Symbols are the same as in Fig. 3.