TITLE: GCN CIRCULAR NUMBER: 22156 SUBJECT: GRB 171124A: Fermi-LAT detection DATE: 17/11/24 11:56:09 GMT FROM: Elisabetta Bissaldi at U.Innsbruk/IAPP F. Longo (University and INFN, Trieste), M. Arimoto (Waseda University), E. Bissaldi (Politecnico and INFN Bari) and M. Palatiello (University and INFN, Trieste) report on behalf of the Fermi-LAT collaboration: At 05:37:56.50 UT on November 24, 2017, Fermi-LAT detected high-energy emission from GRB 171124A, which was also detected by Fermi-GBM (trigger 533194681 / 171124235). The best LAT on-ground location is found to be RA, Dec = 335.52, 35.22 deg (J2000) with an error radius of 0.18 deg (90 % containment, statistical error only). This was 19 deg from the LAT boresight at the time of the trigger. More than 10 photons with Energy > 100 MeV are associated to the GRB in 350 s. The highest-energy photon is a 3.5 GeV event, which is observed 4 seconds after the GBM trigger. A Swift ToO has been approved for this burst. The Fermi-LAT point of contact for this burst is Francesco Longo (francesco.longo@ts.infn.it). The Fermi-LAT is a pair conversion telescope designed to cover the energy band from 20 MeV to greater than 300 GeV. It is the product of an international collaboration between NASA and DOE in the U.S. and many scientific institutions across France, Italy, Japan and Sweden.