Toppanels: median reflex proper motions of galaxies in mas yr⁻¹ on each detector. The error bars are the MAD divided by the square root of the number of galaxies within each detector. The left-hand panel shows the proper motions in the RA direction, whereas the right-hand panel is for the Dec direction. Bottom panels: same as the top panels, but now for the proper motions of the cluster stars.