First four panels (from left to right and top to bottom): Same as Fig. 1, NOAA AR 11591 for Stonyhurst longitude of the centroid (during the first disc passage) of −60°, −30°, 30° & 60°. Last two panels: Same but for the second disc passage (NOAA AR 11612) at longitudes of the centroid around −60° & −30°. All panels are screenshots of the movies corresponding to Figs. 1 & 4, available at online