Estimate of the cross-correlation function for different time lags for long-term light curve of PKS 0048−097 (see Fig. 1). All data are binned in weekly averaged intervals. The following subplots show the CCF for a) optical flux in V band, F_V versus optical flux in R band, F_R as a function of time delay; b) optical flux in V band, F_V versus radio flux F_RADIO as a function of time delay; c) optical flux in V band, F_V versus γ-ray integrated flux I_γ as a function of time delay; d) radio flux, F_RADIO versus γ-ray integrated flux, I_γ as a function of time delay.