*4.2. GRB 180720B*

GRB 180720B is a long GRB at *z* = 0.654 triggered on 20 July 2018 by the Fermi-GBM [158] at *T*<sup>0</sup> = 14 : 21 : 39 UT and 5 s later by the Swift-BAT instrument [159]. The H.E.S.S. telescopes observed and detected GRB 180720B about 11 h after the prompt emission, with a ∼5*σ* statistical significance.
