PATTERNS AND COINCIDENCES IN THE LIGHT CURVES OF ACTIVE GALAXIES

We draw attention to some intriguing coincident patterns in the optica l light curves of NGC 4151 and 5548, Inspecting the light curves of th ese two classic Seyferts, we find evidence for at least five occurrenc es of a similar sequence of variations, This pattern consists of a sim ilar to 2-yr-long sequence of shorter flares, with a total energy of ( 3-5) x 10(50) erg in the B band. We predict that the ongoing monitorin g campaign on NGC 5548 should soon reveal more occurrences of this gen eral pattern if it is truly recurrent. We speculate on the possibility that this pattern is associated with a fundamental/universal 'unit' o f variability in active galaxies, and discuss a possible connection wi th the variability properties of QSOs.