Azimuthal velocity component structure in a narrow region ±5° along the Galactic radius. Top panel: the density of stars normalised at each galactocentric distance. Middle panel: unsharp masking of the density distribution. Bottom panel: same distribution, but colour-coded by the mean radial velocity. Coloured diagonal lines depict the angular momentum selections in a given azimuthal range, using (X_g,Y_g) coordinates to identify the overdensities in Khoperskov et al. (2020a) (see also Fig. 5).