{
  "createdOn": 1758401215448,
  "submitter": "Bagrat Mailyan at Florida Tech <mbagrat@gmail.com>",
  "submittedHow": "web",
  "bibcode": "2025GCN.41917....1M",
  "body": "B. Mailyan (Florida Tech) and C. Meegan (UAH) report on behalf of\nthe Fermi Gamma-ray Burst Monitor Team:\n\n\"At 15:25:17.06 UT on 20 September 2025, the Fermi Gamma-ray Burst Monitor (GBM)\ntriggered and located GRB 250920C (trigger 780074722/250920643)\nwhich was also detected by Swift BAT (R. Gupta et al. 2025, GCN 41904).\nThe Fermi GBM Final Real-time Localization (GCN 41903) is consistent with the Swift BAT position.\n\nThe angle from the Fermi LAT boresight is 94 degrees.\n\nThe GBM light curve consists of multiple emission episodes with a duration (T90)\nof about 36.6 s (50-300 keV). The time-averaged spectrum\nfrom T0+0.003 to T0+37.377 s is best fit by\na Band function with Epeak = 117 +/- 4 keV,\nalpha = -0.76 +/- 0.04, and beta = -2.34 +/- 0.05.\n\nThe event fluence (10-1000 keV) in this time interval is\n(2.97 +/- 0.04)E-05 erg/cm^2. The 1-sec peak photon flux measured\nstarting from T0+26 s in the 10-1000 keV band is 25.1 +/- 0.5 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/\"",
  "eventId": "GRB 250920C",
  "format": "text/plain",
  "circularId": 41917,
  "subject": "GRB 250920C: Fermi GBM Observation"
}