Two-component models (Table 2) that have the same topology on the (Q, U) plane as the fast rotations in Fig. 9a. The model for 8.35 GHz is blue, and that for 10.45 GHz is red. Panel a: as in Fig. 1. Panel b: QU plane for the models in (a). The steady jet is shown as the long vector from the origin, the loops show the tracks of the sum (jet plus burst) vectors. The burst and sum vectors are shown at t = +5. Panel c: flux density and EVPA of the sum. See text.