TITLE:   GCN CIRCULAR
NUMBER:  43511
SUBJECT: GRB 260125B: Fermi GBM Final Real-time Localization
DATE:    26/01/25 10:36:26 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 10:25:45 UT on 25 Jan 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260125B (trigger 791029550.226442 / 260125435).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 77.1, Dec = 17.6 (J2000 degrees, equivalent to J2000 05h 08m, 17d 36'), with a statistical uncertainty of 11.6 degrees.

The angle from the Fermi LAT boresight is 28.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260125435/quicklook/glg_skymap_all_bn260125435.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260125435/quicklook/glg_healpix_all_bn260125435.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260125435/quicklook/glg_lc_medres34_bn260125435.gif