TITLE: GCN CIRCULAR NUMBER: 42852 SUBJECT: GRB 251127A: Fermi GBM Final Real-time Localization DATE: 25/11/27 03:28:10 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 03:17:42 UT on 27 Nov 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 251127A (trigger 785906267.770746 / 251127137).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 155.6, Dec = 30.2 (J2000 degrees, equivalent to J2000 10h 22m, 30d 11'), with a statistical uncertainty of 4.1 degrees.
The angle from the Fermi LAT boresight is 24.0 degrees.
The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251127137/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/bn251127137/q...
The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251127137/q...
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