Variations of different colour indices of RU Vir. The dotted curves were derived from the sinusoidal fits in Fig. 8 as no simultaneous measurements of the individual magnitudes are available for (V − I) and (V − K). To get an idea of how representative these estimates are the same simulated colour curve was derived for (J − K), where photometry at the same epochs is available as well. On the right hand side the amplitudes of the respective colour indices are listed (in brackets if only derived from the simulated variations).