{
  "submitter": "Utkarsh Pathak at IIT Bombay <utkarshpathak.07@gmail.com>",
  "eventId": "GRB 250330A",
  "submittedHow": "web",
  "subject": "GRB 250330A: Fermi GBM Observation",
  "format": "text/plain",
  "bibcode": "2025GCN.39964....1P",
  "circularId": 39964,
  "createdOn": 1743403691016,
  "body": "U. Pathak (IITB), R. Sonawane (IISER, TVM) and C. Meegan (UAH) report on behalf of\nthe Fermi Gamma-ray Burst Monitor Team:\n\n\"At 06:07:38.42 UT on 30 March 2025, the Fermi Gamma-ray Burst Monitor (GBM)\ntriggered and located GRB 250330A (trigger 765007663/250330255).\nwhich was also detected by Swift-BAT (Cenko et al. 2025, GCN 39938).\nThe afterglow has been detected by Swift-XRT (Osborne et al. 2025, GCN 39947).\nThe Fermi GBM Final Localization (GCN 39944) is consistent with the Swift-BAT\nand Swift-XRT positions (Page et al. 2025, GCN 39940).\n\nThe angle from the Fermi LAT boresight is 46 degrees.\n\nThe GBM light curve consists of a single emission episode with a duration\n(T90) of about 4.8 s (50-300 keV). The time-averaged spectrum \nfrom T0-0.6 to T0+6.53 s is best fit by\na power law function with an exponential high-energy cutoff.\nThe power law index is -0.9 +/- 0.1 and the cutoff energy,\nparameterized as Epeak, is 95 +/- 8 keV.\n\nThe event fluence (10-1000 keV) in this time interval is\n(1.50 +/- 0.08)E-06 erg/cm^2. The 1-sec peak photon flux measured\nstarting from T0+0.26 s in the 10-1000 keV band is 6.5 +/- 0.3 ph/s/cm^2.\n\nA Band function fits the spectrum equally well\nwith Epeak= 86 +/- 10 keV, alpha = -0.8 +/- 0.2 and beta = -2.7 +/- 0.4.\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/\""
}