GCN Circular 46029
Subject
GRB 261025B: Fermi GBM Final Real-time Localization
Event
Date
2026-10-25T17:46:25Z (2 days ago)
From
Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply@GIOC.nsstc.nasa.gov>
Via
email
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