TITLE: GCN CIRCULAR NUMBER: 42525 SUBJECT: GRB 251031A: Fermi GBM Final Real-time Localization DATE: 25/10/31 07:31:22 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 07:21:00 UT on 31 Oct 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 251031A (trigger 783588065.486224 / 251031306).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 190.3, Dec = -17.6 (J2000 degrees, equivalent to J2000 12h 41m, -17d 36'), with a statistical uncertainty of 3.3 degrees.
The angle from the Fermi LAT boresight is 49.0 degrees.
The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251031306/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/bn251031306/q...
The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251031306/q...
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