{
  "submitter": "Rushikesh Digambar Sonawane PHD231014 at IISER, TVM <rushikesh23@iisertvm.ac.in>",
  "circularId": 41919,
  "subject": "GRB 250920B: Fermi GBM Observation",
  "createdOn": 1758402218304,
  "submittedHow": "web",
  "eventId": "GRB 250920B",
  "format": "text/plain",
  "bibcode": "2025GCN.41919....1S",
  "body": "R. Sonawane (IISER, TVM) and C. Meegan (UAH) report on behalf of\nthe Fermi Gamma-ray Burst Monitor Team:\n\n\"At 08:46:26.16 UT on 20 September 2025, the Fermi Gamma-ray Burst Monitor (GBM)\ntriggered and located GRB 250920B (trigger 780050791/250920366).\nwhich was also detected by Swift BAT (R. Gupta et al. 2025, GCN 41898),\nSVOM C-GFT (WU et al. 2025, GCN 41908), and Swift UVOT (Kuin et al. 2025, GCN 41915) .\nThe Fermi GBM Final Real-time localization (GCN 41897) is consistent with the Swift BAT position.\n\nThe angle from the Fermi LAT boresight is 56 degrees.\n\nThe GBM light curve consists of multiple emission episodes with a duration (T90)\nof about 127.7 s (50-300 keV). The time-averaged spectrum\nfrom T0-3.6 to T0+141.8 s is best fit by\na Band function with Epeak = 118 +/- 7 keV,\nalpha = -0.85 +/- 0.05, and beta = -2.09 +/- 0.05.\n\nThe event fluence (10-1000 keV) in this time interval is\n(3.33 +/- 0.07)E-05 erg/cm^2. The 1-sec peak photon flux measured\nstarting from T0+9.4 s in the 10-1000 keV band is 8.8 +/- 0.3 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/\""
}