Unbinned light curve (Pacciani 2018) for PKS 1510–08, obtained with P_thr = 1.3 × 10⁻³. Horizontal lines are the statistically relevant clusters. The set of statistically relevant clusters is a tree, and a hierarchy among clusters exists. For each child cluster there is a probability ≤P_thr to be obtained starting from its parent cluster by chance. Vertical bars are the errors on the flux estimate. Background is not subtracted.