{
  "bibcode": "2021GCN.30961....1D",
  "body": "N. Di Lalla (Stanford Univ.), F. Longo (Univ. and INFN, Trieste) and M. Ohno (Hiroshima Univ. & Eotvos Univ) report on behalf of the Fermi-LAT Collaboration:\n\n\nOn October 23rd, 2021, Fermi-LAT detected high-energy emission from GRB 211023A, which was also detected by Fermi GBM (trigger 656687148 / 211023546, GCN 30958). The best LAT on-ground location is found to be:\n\n\nRA, Dec = 72.3, 85.3 (degrees, J2000)\n\n\nwith an error radius of 0.1 deg (90% containment, statistical error only).\n\n\nThe position was 54 deg from the LAT boresight at the time of the GBM trigger:\n\n\nT0 = 13:05:43 UT.\n\n\nThe data from the Fermi-LAT show a significant increase in the event rate after the trigger that is temporally and spatially correlated with the GBM emission with high significance. The photon flux above 100 MeV in the time interval 0-2500 s after the trigger is 3.4 (-/+ 0.6) e-06 ph/cm2/s.\n\n\nThe estimated photon index above 100 MeV is -1.8  (-/+ 0.1).\n\n\nThe highest-energy photon is a 8.6 GeV event which is observed at 1832 seconds after the GBM trigger.\n\n\nA Swift ToO has been requested for this burst.\n\n\nThe Fermi-LAT point of contact for this burst is Donggeun Tak (takdg123@gmail.com<mailto:takdg123@gmail.com>).\n\n\nThe 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.",
  "circularId": 30961,
  "createdOn": 1635027944000,
  "email": "niccolo.dilalla@stanford.edu",
  "subject": "GRB 211023A: Fermi-LAT detection",
  "submitter": "Niccolo Di Lalla at Stanford U  <niccolo.dilalla@stanford.edu>",
  "eventId": "GRB 211023A"
}