TITLE: GCN CIRCULAR NUMBER: 42497 SUBJECT: GRB 251028A: Fermi GBM Final Real-time Localization DATE: 25/10/28 03:36:52 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 03:26:31 UT on 28 Oct 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 251028A (trigger 783314796.860488 / 251028143).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 149.5, Dec = 20.2 (J2000 degrees, equivalent to J2000 09h 58m, 20d 11'), with a statistical uncertainty of 1.0 degrees.

The angle from the Fermi LAT boresight is 53.0 degrees.

The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251028143/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/bn251028143/q...

The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251028143/q...

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