Model-fitting results of the kinematic features for knot C20 including trajectory, core separation, coordinates, apparent velocity, viewing angle, Lorentz factor, and Doppler factor. Upper left panel: the green and blue lines represent the fitting model trajectories calculated for precession phases ω ± 0.63 rad. Bottom right panel: the green and blue lines represent the precessing common parabolic trajectories calculated for precession phases ω ± 0.63 rad.