Two of the S Per features matched in 1994 (circles) and 1999 (triangles), marked on Fig. 5. The velocity ranges are  − 45.7 to  − 35.9 km s^-1 and  − 32.8 to  − 28.5 km s^-1 respectively, see Fig. 5 for colour scale. The left-hand feature has rotated counterclockwise, in bulk, and moved slightly S between 1994 and 1999. The right-hand feature has moved to the SW whilst retaining the elongated distribution of the components.