(a) Distributions of the 22 GHz H₂O maser features obtained after rotating the plot in Fig. 5 by 43.5 degrees. The abscissa is parallel to the outflow as indicated by a solid line in Fig. 5. Horizontal bars at the bottom right corner indicate the minimum, maximum, and mean positions of the SW lobealong the outflow axis for each epoch (2005, 2010, and 2017 from bottom to top). (b) Same as (a), where the displacement along the Y axis has been replaced by the observing epoch. The black solid line represents the movement of the head of the bow shock along the outflow axis.