TITLE:   GCN CIRCULAR
NUMBER:  45772
SUBJECT: GRB 260928A: Fermi GBM Final Real-time Localization
DATE:    26/09/28 00:41:50 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 SHORT GRB

At 00:31:16 UT on 28 Sep 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260928A (trigger 812248281.78187 / 260928022).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 290.5, Dec = 8.1 (J2000 degrees, equivalent to J2000 19h 22m, 8d 05'), with a statistical uncertainty of 9.8 degrees.

The angle from the Fermi LAT boresight is 44.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260928022/quicklook/glg_skymap_all_bn260928022.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/bn260928022/quicklook/glg_healpix_all_bn260928022.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260928022/quicklook/glg_lc_medres34_bn260928022.gif