TITLE:   GCN CIRCULAR
NUMBER:  45888
SUBJECT: GRB 261010A: Fermi GBM Final Real-time Localization
DATE:    26/10/10 19:27:41 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 19:17:03 UT on 10 Oct 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 261010A (trigger 813352628.162212 / 261010804).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 244.7, Dec = 27.6 (J2000 degrees, equivalent to J2000 16h 18m, 27d 36'), with a statistical uncertainty of 3.3 degrees.

The angle from the Fermi LAT boresight is 25.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn261010804/quicklook/glg_skymap_all_bn261010804.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/bn261010804/quicklook/glg_healpix_all_bn261010804.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn261010804/quicklook/glg_lc_medres34_bn261010804.gif