Triplet distribution. This is the distribution of the time intervals Δt of the photon triplets with (filled green) and without (red line) considering the correction of the bad intervals due to the LAT orbit and field of view. The expected distribution for independent events is shown as a black line. The vertical lines represent the first photon triplet after T₀ (in cyan) and the shortest duration triplet in the two weeks after T₀ (in blue), respectively. The latter is obtained from an analysis of a two-week interval after T₀ in order to account for the uncertainty on the estimated T₀, as well as for a possible delay in the γ-ray emission from the SN. A significant triplet would appear in the left tail of the distribution. This is not the case for either of the highlighted triplets.