{
  "createdOn": 1776745356864,
  "circularId": 44360,
  "subject": "GRB 260421B: Fermi GBM Final Real-time Localization",
  "body": "The Fermi GBM team reports the detection of a likely LONG GRB\n\nAt 04:13:21 UT on 21 Apr 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260421B (trigger 798437606.166588 / 260421176).\n\nThe on-ground calculated location, using the Fermi GBM trigger data, is RA = 188.8, Dec = -17.8 (J2000 degrees, equivalent to J2000 12h 35m, -17d 48'), with a statistical uncertainty of 2.4 degrees.\n\nThe angle from the Fermi LAT boresight is 58.0 degrees.\n\nThe skymap can be found here:\nhttps://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260421176/quicklook/glg_skymap_all_bn260421176.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/2026/bn260421176/quicklook/glg_healpix_all_bn260421176.fit\n\nThe GBM light curve can be found here:\nhttps://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260421176/quicklook/glg_lc_medres34_bn260421176.gif\n",
  "eventId": "GRB 260421B",
  "submitter": "Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply@GIOC.nsstc.nasa.gov>",
  "submittedHow": "email"
}