Position velocity diagrams along the major axis (ϕ ∼ 220°) for CO(3−2) (left) and HCO⁺(4−3) (right). The data are shown in grey-scale and blue contours; the model with ^3DBAROLO is overplotted in red contours, the values of the modelled line-of-sight velocities v_los = sini × v_rot are plotted as yellow filled circles. For HCO⁺(4−3), the expected Keplerian rotation curve for a (1.7 ± 0.3) × 10⁶ M_⊙ black hole (Greenhill et al. 2003) is indicated in blue.