TITLE: GCN CIRCULAR NUMBER: 43844 SUBJECT: GRB 260226A: Fermi-LAT detection of a bright burst DATE: 26/02/26 13:34:45 GMT FROM: Davide Depalo at Politecnico and INFN Bari <davide.depalo@ba.infn.it> D. Depalo (Politecnico and INFN Bari), E. Bissaldi (Politecnico and INFN Bari), S. Zhu (DESY), R. Gupta (NASA/GSFC), J. L. Racusin (NASA/GSFC), F. Longo (Univ and INFN Trieste) report on behalf of the Fermi-LAT Collaboration: At 10:38:18.84 UT on Feb 26, 2026, Fermi-LAT triggered on high-energy emission from GRB 260226A, also detected by GBM (trigger 793795080.95811 / 260226443, GCN Circular 43840) at 10:37:55 UT. Note that this is a rare onboard detection seeded by LAT, independent of the GBM trigger, which is why the trigger times differ. LAT-seeded alerts have a very high threshold and this is only the second GRB to have passed this alert after GRB 090510. The onboard location is RA, Dec 42.050, +8.033 with an approximate error radius of 0.5 deg (90% containment, systematic error only). This was 17 deg from the LAT boresight at the time of the trigger. We anticipate providing a refined location within the next 12 hours when the LAT science data for this burst are downlinked and processed. The Fermi-LAT point of contact for this burst is Niccolò 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. View this GCN Circular online at https://gcn.nasa.gov/circulars/43844. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...