A visualization of the time delay between the 1.3-mm and 3-mm lightcurves of 3C 84. Left panel: the 1.3-mm and 3-mm lightcurves. Each lightcurve is normalized to zero mean and unity standard deviation, in analogy to the calculation of the unbinned discrete correlations according to Eq. (7). Here S_ν indicates the flux density,  ⟨ S_ν ⟩  is the average flux density, and σ denotes the standard deviation of each lightcurve. Right panel: same as left panel, but with the 1.3-mm lightcurve artificially retarded by 300 days. Comparison of the two panel shows improved agreement of the two lightcurves when taking into account the time delay τ ≈ −300 days found from the discrete correlation function; see also Fig. 7, bottom right panel.