Top: rotational velocity model adopted for NGC 1433, based on the Hα kinematics (red filled squares) from Buta et al. (2001), compatible with the CO rotation curve (green filled hexagons). The CO velocity field is, however, sparsely sampled. Bottom: velocity residuals after subtraction of a regular rotation model, based on the Hα rotation curve above. The map has been recentred on the new adopted centre given in Table 1. The two orthogonal lines indicate the position of the PV diagrams in Fig. 7.