Maps of velocity corrections required as a result of uneven slit illumination, for both PA 160° (left) and PA 340° (right). Top panels are computed by modelling the uneven slit illumination effect in each spaxel. Bottom panels are measured velocity centroid shifts relative to the central spectrum for the photospheric line near 16 755 Å, as a double-check on the model output. Black contours show the position of the approaching jet.