{
  "bibcode": "2022GCN.31659....1O",
  "body": "N. Omodei, N. Di Lalla (Stanford University), R. Pillera (INFN Bari) \nreport on behalf of the Fermi-LAT team:\n\nOn February 28, 2022, Fermi-LAT detected high-energy emission from GRB \n220228A, which was also detected by**Fermi-GBM (trigger 667737010 / \n220228438, GCN 31658).\n\nThe best LAT on-ground location is found to be\n\nRA, Dec = 311.2, -22.7 (degrees, J2000)\n\nwith an error radius of 0.7 deg (90 % containment, statistical error \nonly). This was 23 deg from the LAT boresight at the time of the trigger:\n\nT0 = 10:30:05.92 UT.\n\nThe data from the Fermi-LAT show a significant increase in the event \nrate that is spatially and temporally correlated with the GBM emission \nwith high significance. The photon flux above 90 MeV in the time \ninterval 0-1000s after the GBM trigger is 4E-6 �� 1E-6 ph/cm2/s.\n\nThe estimated photon index above 90 MeV is -2.9 �� 0.4.\n\nThe highest-energy photon is a 323 MeV**event which is observed 77 \nseconds after the GBM trigger.\n\nA Swift ToO has been requested for this burst.\n\nThe Fermi-LAT point of contact for this burst is Roberta \nPillera**(roberta.pillera@ba.infn.it).\n\nThe Fermi-LAT is a pair conversion telescope designed to cover the \nenergy band from 20 MeV to greater than 300 GeV. It is the product of an \ninternational collaboration between NASA and DOE in the U.S. and many \nscientific institutions across France, Italy, Japan and Sweden.",
  "circularId": 31659,
  "createdOn": 1646086003000,
  "email": "niccolo.dilalla@stanford.edu",
  "subject": "GRB 220228A: Fermi-LAT detection",
  "submitter": "Niccolo Di Lalla at Stanford U  <niccolo.dilalla@stanford.edu>",
  "eventId": "GRB 220228A"
}