TITLE:   GCN CIRCULAR
NUMBER:  46029
SUBJECT: GRB 261025B: Fermi GBM Final Real-time Localization
DATE:    26/10/25 17:46:25 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 SHORT GRB

At 17:38:31 UT on 25 Oct 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 261025B (trigger 814642716.94305 / 261025735).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 258.2, Dec = 24.8 (J2000 degrees, equivalent to J2000 17h 12m, 24d 48'), with a statistical uncertainty of 4.6 degrees.

The angle from the Fermi LAT boresight is 30.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn261025735/quicklook/glg_skymap_all_bn261025735.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/bn261025735/quicklook/glg_healpix_all_bn261025735.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn261025735/quicklook/glg_lc_medres34_bn261025735.gif