Model-fitting results of the kinematic features for knot C23 (first 6 panels, from top left to bottom right) and for knot C24 (last six panels) including trajectory, core separation, coordinates, apparent velocity, viewing angle, Lorentz factor, and Doppler factor. In the 1st and 7th panels, the green and blue lines represent the fitting model trajectories calculated for precession phases ω ± 0.63 rad. In the 6th and 12th panels, the green and blue lines represent the precessing common parabolic trajectories calculated for precession phases ω ± 0.63 rad. For both C23 and C24 a number of data points are within the position angle range defined by the two lines, indicating that their innermost trajectories have been observed to follow the precessing common parabolic trajectory.