TITLE:   GCN CIRCULAR
NUMBER:  46044
SUBJECT: GRB 261026C: Fermi GBM Final Real-time Localization
DATE:    26/10/26 14:05:13 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 13:55:43 UT on 26 Oct 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 261026C (trigger 814715748.208736 / 261026580).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 129.1, Dec = 7.0 (J2000 degrees, equivalent to J2000 08h 36m, 7d 00'), with a statistical uncertainty of 3.8 degrees.

The angle from the Fermi LAT boresight is 45.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn261026580/quicklook/glg_skymap_all_bn261026580.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/bn261026580/quicklook/glg_healpix_all_bn261026580.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn261026580/quicklook/glg_lc_medres34_bn261026580.gif