The distributions of the spotted area vs. longitude at the labelled times (HJD−2  454  000.0) for Q = 0.0. The plots have been vertically shifted to show the migration of individual spots (relative maxima of the distributions) versus time. The vertical short-dashed lines mark longitudes 0° and 360°, beyond which the distributions have been repeated to help following the spot migration. The long-dashed lines labelled with capital letters from A to E trace the migration of the most conspicuous spots detected in the plots, respectively (see the text).