TITLE:   GCN CIRCULAR
NUMBER:  44174
SUBJECT: GRB 260401A: Fermi GBM Final Real-time Localization
DATE:    26/04/01 11:02:02 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 10:53:26 UT on 1 Apr 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260401A (trigger 796733611.002678 / 260401454).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 219.5, Dec = -17.4 (J2000 degrees, equivalent to J2000 14h 37m, -17d 23'), with a statistical uncertainty of 1.6 degrees.

The angle from the Fermi LAT boresight is 60.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260401454/quicklook/glg_skymap_all_bn260401454.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/bn260401454/quicklook/glg_healpix_all_bn260401454.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260401454/quicklook/glg_lc_medres34_bn260401454.gif