Top (left): range of the precessing trajectory. The numbers mentioned in the legend are relative precession phases (in units of radians). Top (right): results of the fitting process of the trajectories within 0.5 mas of core-separation. Bottom (left): change of the knot trajectories beyond 0.5 mas. phi denotes for the relative precession phase of the knots. Bottom (right): fitting of the position-angle deviations is consistent with a swing period of 16.9 yr.