TITLE: GCN CIRCULAR NUMBER: 40050 SUBJECT: GRB 250404A: Fermi GBM Final Real-time Localization DATE: 25/04/04 14:30:25 GMT FROM: Fermi GBM Team at MSFC/Fermi-GBM do_not_reply@GIOC.nsstc.nasa.gov
The Fermi GBM team reports the detection of a likely LONG GRB
At 14:19:46 UT on 4 Apr 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250404A (trigger 765469191.347644 / 250404597).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 123.4, Dec = 34.1 (J2000 degrees, equivalent to J2000 08h 13m, 34d 06'), with a statistical uncertainty of 1.2 degrees.
The angle from the Fermi LAT boresight is 42.0 degrees.
The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250404597/q...
The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250404597/q...
The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250404597/q...
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