{
  "submittedHow": "web",
  "createdOn": 1742005067458,
  "bibcode": "2025GCN.39726....1N",
  "submitter": "eliza.neights@gmail.com",
  "format": "text/plain",
  "body": "Eliza Neights (George Washington University, NASA Goddard Space Flight Center), M. Godwin (UAH), C. Meegan (UAH) and O.J. Roberts (USRA) report on behalf of\nthe Fermi Gamma-ray Burst Monitor Team:\n\n\"At 14:34:33.69 UT on 13 March 2025, the Fermi Gamma-ray Burst Monitor (GBM)\ntriggered and located GRB 250313A (trigger 763569278/250313607), which was also detected by Fermi LAT (Di Lalla et al. 2025, GCN 39711), AstroSat CZTI (Dasgupta et al. 2025, GCN 39714), \nSVOM/GRM (Wang et al. 2025, GCN 39716), and Konus-Wind (Frederiks et al. 2025, GCN 39721).\n\nThe Fermi GBM Final Position location is consistent with the Fermi LAT position.\n\nThe angle from the Fermi LAT boresight is 4 degrees.\n\nThe GBM light curve consists of two emission episodes, a bright pulse lasting 12 s after the trigger time and a dimmer pulse about 280 s later. The duration (T90)\nis about 295.2 s (50-300 keV). The time-averaged spectrum\nfrom T0-2.2 to T0+389.0 s is best fit by\na power law function with an exponential high-energy cutoff.\nThe power law index is -1.36 +/- 0.01 and the cutoff energy,\nparameterized as Epeak, is 320 +/- 20 keV.\n\nThe event fluence (10-1000 keV) in this time interval is\n(9.4 +/- 0.1)E-05 erg/cm^2. The 1-sec peak photon flux measured\nstarting from T0+4.7 s in the 10-1000 keV band is 55.4 +/- 0.5 ph/s/cm^2.\n\nThe spectrum is fit about equally well by a Band function with Epeak = 280 +/- 20 keV, alpha = -1.34 +/- 0.02, and beta = -2.23 +/- 0.13.\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": 39726,
  "eventId": "GRB 250313A",
  "subject": "GRB 250313A: Fermi GBM Detection"
}