a) Time lag measurements vs. frequency using 15 GHz as the reference frequency for the radio flare R6. The best fitted power law at radio and mm frequencies is extended up to the optical wavelengths. The near by optical, X-ray and GeV flares are shown with their possible time lags w.r.t. R6. b) The same for the R8 flare (see Fig. 2 for flare labeling) In both plots, the dashed lines indicate the SSC process with simultaneous optical-γ-ray events.