GCN 45618: GRB 260917C: Fermi GBM Final Real-time Localization

2026-09-18T00:04:34.516Z | rev 0 | event: GRB 260917C

The Fermi GBM team reports the detection of a likely LONG GRB

At 23:54:04 UT on 17 Sep 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260917C (trigger 811382049.420122 / 260917996).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 155.6, Dec = -46.8 (J2000 degrees, equivalent to J2000 10h 22m, -46d 47'), with a statistical uncertainty of 5.2 degrees.

The angle from the Fermi LAT boresight is 103.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260917996/quicklook/glg_skymap_all_bn260917996.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/bn260917996/quicklook/glg_healpix_all_bn260917996.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260917996/quicklook/glg_lc_medres34_bn260917996.gif