Symmetrised midplane rotation curves extracted from the line emission velocity maps in Figs. A.1–A.8 (black line) and their fit with Eq. (2) (red line). All panels cover the same physical scale (horizontal axis) and the same velocity scale (vertical axis). The lower-right corner of each panel shows the best fit parameters where v_c is the circular velocity, x_f is the axial coordinate of the flattening of the rotation curve, and γ describes the sharpness of the transition between a rising and the flat sections. The horizontal dashed lines indicate v_c and the vertical dashed lines indicate x_f. The panels are ordered by descending v_c.