OH maser proper motions measured with the VLBA toward W51e2-E (Fish & Reid 2007). The position (circles) and proper motions (arrows) of OH masers are overlaid onto the total intensity (0th moment) map of the (6, 6) inversion transition of NH₃ (same as Fig. 15). Colors denote l.o.s. velocity (color scale on the right-hand side) and the scale for the proper motion amplitude is given in the bottom right corner (both in km s^-1). The proper motions seems to trace a slow wide-angle expansion around W51e2-E as well as a filamentary structure south of the HC HII region.