TITLE: GCN CIRCULAR NUMBER: 42696 SUBJECT: GRB 251115A: Fermi-LAT detection DATE: 25/11/15 12:51:17 GMT FROM: A. Holzmann Airasca at University of Trento and INFN Bari <a.holzmannairasca@unitn.it> E. Bissaldi (Politecnico and INFN Bari), A. Holzmann Airasca (UniTrento and INFN Bari), R. Gupta (NASA GSFC), T. Nymark (KTH), F. Longo (University and INFN, Trieste) and S. Lopez (CNRS / IN2P3) report on behalf of the Fermi-LAT Collaboration: On November 15, 2025, Fermi-LAT detected high-energy emission from GRB 251115A, which was also detected by Fermi-GBM (trigger 784869607 / 251115139, GCN 42692) and Global MASTER (GCN 42694). The best LAT on-ground location is found to be: RA, Dec = 330.18, -9.18 (J2000) with an error radius of 0.36 deg (90 % containment, statistical error only). This was 80 deg from the LAT boresight at the time of the GBM trigger (T0 = 03:20:02.67 UT). The data from the Fermi-LAT shows a significant increase in the event rate that is spatially and temporally correlated with the GBM emission with high significance. The photon flux above 100 MeV in the time interval 0 - 600 s after the GBM trigger is (1.04 ± 0.34) E-5 ph/cm2/s. The estimated photon index above 100 MeV is -2.5 ± 0.4. The highest-energy photon is a 1.6 GeV event which is observed ~ 490 seconds after the GBM trigger. A Swift ToO has been approved for this burst. The Fermi-LAT point of contact for this burst is Tanja Kramer Nymark (tanjan@kth.se). 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/42696. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...