Proper motions of the 6.7 GHz methanol maser emission in Cep A relative to the barycenter (see Sect. 3.2). Arrows show the direction of the measured proper motions (solid line: using three epochs, dotted line: only two epochs). Arrow length is proportional to the magnitude of the tangential velocity. The spatial and velocity scales are shown at the lower right corner in each panel. The filled circles show the position of the maser spots. The open circle indicates the barycenter of epoch 1. a) Entire map, b)–e) Close-up maps for clusters I/II, III, IV, and V, respectively.