TITLE: GCN CIRCULAR NUMBER: 30687 SUBJECT: GRB 210822A: Fermi-LAT detection DATE: 21/08/22 20:02:07 GMT FROM: Masanori Ohno at Hiroshima U M. Ohno (Eotvos U./Hiroshima U.), D. Kocevski (NASA/MSFC), F. Longo (University and INFN, Trieste), a F. Dirirsa (LAPP, Annecy) report on behalf of the Fermi-LAT Collaboration: On August 22th, 2021, Fermi-LAT detected high-energy emission from GRB 210822A, which was also detected by Swift-BAT (trigger1069788; Page et al. GCN Circ. 30677) and GECAM (Wang et al., GCN Circ. 30678). The best LAT on-ground location is found to be RA, Dec 304.6, 4.9 (degrees, J2000) with an error radius of 0.5 deg (90% containment, statistical error only). This was 83 deg from the LAT boresight at the time of the Swift trigger: T0 = 09:18:18 UT. And the burst came into the LAT boresight about 500 s after the Swift trigger time. The data from the Fermi-LAT show a significant increase in the event rate after the Swift trigger that is spatially correlated with the Swift emission with high significance. The photon flux above 100 MeV in the time interval 500-10000 s after the Swift trigger is 2.5(-/+ 0.8) ph/cm2/s. The estimated photon index above 100 MeV is -2.4 (-/+ 0.3). The highest-energy photon is a 1.0 GeV event which is observed 855 seconds after the Swift trigger. The Fermi-LAT point of contact for this burst is Feraol F. Dirirsa (dirirsa@lapp.in2p3.fr ). 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.