Fig. 1: The 1∘ × 1∘ Fermi-LAT counts map.
From: A delayed 400 GeV photon from GRB 221009A and implication on the intergalactic magnetic field
The map is centered at the Swift/Ultra-violet Optical Telescope (UVOT) localization (i.e., the blue triangle) for the Fermi-LAT observations in the time interval of 0.05 − 1 days (after the burst). The red filled dot is on behalf of the delayed 397.7 GeV photon we report. The pink filled dots represent other Fermi-LAT event which is in the energy range of 0.5 GeV − 100 GeV. The gold star marks the localization of the Large High Altitude Air Shower Observatory’s Water Cherenkov Detector Array (LHAASO-WCDA)29 and the gray square represents localization of the Very Long Baseline Array (VLBA)32. The 68% and 95% containment angles for Fermi-LAT at 400 GeV40 are also shown as red dashed and dotted circular lines, respectively. Source data are provided as a Source Data file.
