TITLE:   GCN CIRCULAR
NUMBER:  45603
SUBJECT: GRB 260917A: Fermi GBM Final Real-time Localization
DATE:    26/09/17 02:34:35 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 02:24:08 UT on 17 Sep 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260917A (trigger 811304653.400746 / 260917100).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 311.6, Dec = -32.8 (J2000 degrees, equivalent to J2000 20h 46m, -32d 47'), with a statistical uncertainty of 1.7 degrees.

The angle from the Fermi LAT boresight is 121.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260917100/quicklook/glg_skymap_all_bn260917100.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/bn260917100/quicklook/glg_healpix_all_bn260917100.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260917100/quicklook/glg_lc_medres34_bn260917100.gif