Position-velocity diagram of NGC 3198 along the major axis, considering a position angle of 213°. The observed position-velocity diagram is shown in black and the model is in red. The model shown here is derived with a thin disk only (plus noise), convolved with the dirty beam, CLEANed and restored as described at the end of Sect. 4. Contours are −0.3, 0.3 (~1.5σ), 3, and 30 mJy beam^-1.