Same as in Fig. A.3 for Mrk 142 (data taken from C20). To increase the spectra coverage and the number of variance data within the spectral width of the Swift filters we also used light curves from ground-based telescopes for this source. These light curves are well sampled and significantly longer than the Swift light curves. We plot the r−band light curve in this figure; the segments we used to compute the excess variance in the u, g, i and z−band light curves (data taken from C20 as well) are very similar to the ones indicated in the r−band light curve.