Plots in galactocentric Cartesian coordinates of the isolated NSD (left), strong NSB (middle), and weak NSB (right) models oriented at −60° relative to the Sun-GC line. Overlaid are the velocity ellipses coloured by the vertex deviation, l_v. We have placed an ellipse in each bin with N > 25 stars. The dashed lines reflect a 2° field of view centred on the Solar position at (x, y) = (−8.2, 0) kpc. The NSD shows radially oriented ellipses, while the S-NSB model ellipses show strong alignment with the bar’s major axis. The alignment is weaker for the W-NSB model.