Model fitting of the kinematics for knot i: trajectory Z_n-X_n, core separation r_n(t), coordinates X_n(t) and Z_n(t), the modeled apparent velocity/viewing angle and Lorentz/Doppler factor. The initial acceleration is apparent (from ~6.8c to ~14c). In the upper plots, two additional model (red and green) curves calculated for ejection epochs t₀ + 0.3 yr and t₀−0.3 yr are shown, indicating that most of the observational data points are within the regions confined by the two curves and that the precession period is determined with an uncertainty of ~0.3 yr.