Upper panel: distribution of the studied clusters in the l–v_GSR plane. The symbols change as a function of Galactocentric radius. v_GSR has been computed assuming (U_⊙, V_⊙, W_⊙) = (10.7,15.6,8.9) km s⁻¹ and Θ₀ = 240 km s⁻¹ from Reid et al. (2014). Lines represent circular orbits at different radii showing the rotation curve derived by Reid et al. (2014). Errors in v_GSR are not plotted since they are smaller than the point size (see Table 9). Lower panel: differences between the velocities of the clusters with respect to the GSR and the circular velocity at the position of each cluster v_GSR − v_{GSR, rot}.