Best-fit model and residuals (i.e. observation minus the model) obtained with 3DB for the rotating disc with a radial velocity component. Top and bottom panels show the mean velocity field and the velocity dispersion field of CO(3 − 2), respectively. In the first panel, v_sys = 1872 km s⁻¹ has been subtracted from the model velocities. Velocity contours (top panels) are at −50 and 50 km s⁻¹ (solid) and at 0 km s⁻¹ (dotted), while dispersion contours (bottom panels) are at −50, −25, 25, and 50 km s⁻¹ (solid) and at 0 km s⁻¹ (dotted). The dashed black line in the first panel is the kinematic major axis with PA = 265°. The ALMA beam appears in every panel as a black ellipse in the bottom left.