{
  "eventId": "GRB 250421A",
  "submitter": "Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply@GIOC.nsstc.nasa.gov>",
  "circularId": 40191,
  "submittedHow": "email",
  "body": "The Fermi GBM team reports the detection of a likely LONG GRB\n\nAt 10:38:31 UT on 21 Apr 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250421A (trigger 766924716.344264 / 250421443).\n\nThe on-ground calculated location, using the Fermi GBM trigger data, is RA = 249.1, Dec = -59.9 (J2000 degrees, equivalent to J2000 16h 36m, -59d 53'), with a statistical uncertainty of 3.8 degrees.\n\nThe angle from the Fermi LAT boresight is 103.0 degrees.\n\nThe skymap can be found here:\nhttps://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250421443/quicklook/glg_skymap_all_bn250421443.png\n\nThe HEALPix FITS file, including the estimated localization systematic, can be found here:\nhttps://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250421443/quicklook/glg_healpix_all_bn250421443.fit\n\nThe GBM light curve can be found here:\nhttps://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250421443/quicklook/glg_lc_medres34_bn250421443.gif\n",
  "bibcode": "2025GCN.40191....1F",
  "createdOn": 1745232539015,
  "subject": "GRB 250421A: Fermi GBM Final Real-time Localization"
}