{
  "bibcode": "2025GCN.40030....1S",
  "createdOn": 1743701350126,
  "subject": "GRB 250402A: Fermi GBM Observation",
  "format": "text/plain",
  "submitter": "Matt Godwin <msg0028@uah.edu>",
  "circularId": 40030,
  "eventId": "GRB 250402A",
  "submittedHow": "web",
  "body": "Jacob Smith (UAH), Utkarsh Pathak(IIT Bombay), and Matt Godwin (UAH) report on behalf of\nthe Fermi Gamma-ray Burst Monitor Team:\n\n\"At 23:08:09.09 UT on 02 April 2025, the Fermi Gamma-ray Burst Monitor (GBM)\ntriggered and located GRB 250402A (trigger 765328094/250402964).\nwhich was also detected by SVOM (Chen et al. 2025, GCN 40014).\nThe Fermi GBM on-ground location is consistent with the SVOM position.\n\nThe angle from the Fermi LAT boresight is 57 degrees.\n\nThe GBM light curve consists of a double peak with a duration (T90)\nof about 44 s (50-300 keV). The time-averaged spectrum\nfrom T0-5.1 to T0+45.1 s is best fit by\na power law function with an exponential high-energy cutoff.\nThe power law index is -1.1 +/- 0.1 and the cutoff energy,\nparameterized as Epeak, is 115 +/- 10 keV.\n\nThe event fluence (10-1000 keV) in this time interval is\n(4.1 +/- 0.2)E-06 erg/cm^2. The 1-sec peak photon flux measured\nstarting from T0+23 s in the 10-1000 keV band is 2.4 +/- 0.2 ph/s/cm^2.\n\nA Band function fits the spectrum equally well\nwith Epeak= 60 +/- 10 keV, alpha = -0.4 +/- 0.3 and beta = -2.1 +/- 0.1.\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/\""
}