{
  "createdOn": 1750895872606,
  "body": "O. Mukherjee (USRA) and C. Meegan (UAH) report on behalf of\nthe Fermi Gamma-ray Burst Monitor Team:\n\n\"At 13:22:56.94 UT on 20 June 2025, the Fermi Gamma-ray Burst Monitor (GBM)\ntriggered and located GRB250620B (trigger 772118581/250620558).\nwhich was also detected by Swift/BAT-GUANO (S. Ronchini et al. 2025, GCN 40800).\nThe Fermi GBM on-ground location is consistent with the Swift/BAT-GUANO position.\n\nThe angle from the Fermi LAT boresight is 90 degrees.\n\nThe GBM light curve consists of a single emission episode with a duration (T90)\nof about 23 s (50-300 keV). The time-averaged spectrum\nfrom T0-2 to T0+23.6 s is best fit by\na power law function with an exponential high-energy cutoff.\nThe power law index is -1.3 +/- 0.1 and the cutoff energy,\nparameterized as Epeak, is 430 +/- 236 keV.\n\nThe event fluence (10-1000 keV) in this time interval is\n(2.7 +/- 0.4)E-06 erg/cm^2. The 1-sec peak photon flux measured\nstarting from T0+0.7 s in the 10-1000 keV band is 1.9 +/- 0.2 ph/s/cm^2.\n\nThe spectral analysis results presented above are preliminary;\nfinal results will be published in the GBM GRB Catalog:\nhttps://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html\n\nFor Fermi GBM data and info, please visit the official Fermi GBM Support Page:\nhttps://fermi.gsfc.nasa.gov/ssc/data/access/gbm/\"",
  "circularId": 40829,
  "eventId": "GRB 250620B",
  "subject": "GRB 250620B: Fermi GBM Observation",
  "submittedHow": "web",
  "format": "text/plain",
  "bibcode": "2025GCN.40829....1M",
  "submitter": "oindabimukherjee@gmail.com"
}