TITLE: GCN CIRCULAR NUMBER: 27797 SUBJECT: GRB 200524A: Fermi-LAT detection DATE: 20/05/24 14:49:12 GMT FROM: Masanori Ohno at Hiroshima University F. Fana Dirirsa (Univ. of Johannesburg), M. Axelsson (KTH & Stockholm Univ.), M. Ohno (Hiroshima Univ.), F. Piron (CNRS/IN2P3/LUPM) and F. Longo (University and INFN, Trieste) report on behalf of the Fermi-LAT Collaboration: On May 24, 2020, Fermi-LAT detected high-energy emission from GRB 200524A, which was also detected by Fermi-GBM (trigger 611989445). At the time of the trigger (T0 = 05:04:00.36 UT) Fermi-LAT was passing through the SAA, and observations started at roughly T0+110 seconds. The GRB is detected at high energy (>100 MeV) by Fermi-LAT at a location of: RA, Dec = 212.8, 61.0 (degrees, J2000) with an error radius of 0.2 deg (90% containment, statistical error only). This was ~25 deg from the LAT boresight when observations started (T0+110s), and is ~3 deg from the GBM final ground position. The photon flux above 100 MeV in the time interval 110-900 s after the GBM trigger is 2.2e-06 +/- 0.8e-06 ph/cm2/s. The estimated photon index above 100 MeV is -1.7 +/ - 0.2. The highest-energy photon is a 9.2 GeV event which is observed 748 seconds after the GBM trigger. After ~T0+900s, the GRB location moved outside the LAT FoV. A Swift ToO has been approved for this burst. The Fermi-LAT point of contact for this burst is Feraol Fana Dirirsa (fdirirsa@uj.ac.za ). 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.