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/quicklook/glg_skymap_all_bn251028143.png

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/quicklook/glg_healpix_all_bn251028143.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251028143/quicklook/glg_lc_medres34_bn251028143.gif