GCN 44195: GRB 260403A: Fermi GBM Final Real-time Localization

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

At 02:31:27 UT on 3 Apr 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260403A (trigger 796876292.704364 / 260403105).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 236.2, Dec = -31.0 (J2000 degrees, equivalent to J2000 15h 44m, -31d 00'), with a statistical uncertainty of 5.0 degrees.

The angle from the Fermi LAT boresight is 86.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260403105/quicklook/glg_skymap_all_bn260403105.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/bn260403105/quicklook/glg_healpix_all_bn260403105.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260403105/quicklook/glg_lc_medres34_bn260403105.gif