Top: weekly averaged normalized flux at γ-ray and optical V band frequencies plotted vs. time. The flux variations at these two frequencies seem to have a one-to-one correlation with each other. Bottom left: γ-ray vs. optical flux. Bottom right: the DCF curve of γ-ray vs. optical V passband flux using a bin size of 10-day in each case. A: using the complete data as shown in Fig. 2; B: after removing the data covering the duration of the optical flare O6; C: using the data before flare O6.