TITLE: GCN CIRCULAR NUMBER: 30062 SUBJECT: GRB 210520A: Fermi-LAT detection DATE: 21/05/21 05:15:00 GMT FROM: Magnus Axelsson at Stockholm U. N. Di Lalla (Stanford Univ.), M. Arimoto (Kanazawa Univ.), M. Axelsson (KTH & Stockholm Univ.), D. Kocevski (NASA/MSFC), N. Omodei (Stanford Univ.) report on behalf of the Fermi-LAT Collaboration: On May 20, 2021 Fermi-LAT detected high-energy emission from GRB 210520A, which was also detected by Fermi-GBM (trigger 643230427.939988 / 210520797, GCN 30059). The best LAT on-ground location is found to be (RA, Dec) = 123.0, -69.4 (degrees, J2000) with an error radius of 0.7 deg (90% containment, statistical error only). This was 21 deg from the LAT boresight at the time of the GBM trigger: T0 = 19:07:02 UT. The data from the Fermi-LAT show a significant increase in the event rate after the GBM trigger that is spatially and temporally correlated with the GBM emission (9 degrees from the GBM location) with high significance. The photon flux above 100 MeV in the time interval 0-100s after the GBM trigger is (2.5 +/- 0.7) e-05 ph/cm2/s. The estimated photon index above 100 MeV is -2.6 +/- 0.4. A Swift ToO has been approved for this burst. The Fermi-LAT point of contact for this burst is Niccolo' Di Lalla (niccolo.dilalla@stanford.edu). 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.