TITLE:   GCN CIRCULAR
NUMBER:  44238
SUBJECT: GRB 260404A: Fermi GBM Final Localization
DATE:    26/04/08 19:07:24 GMT
FROM:    atrigg2@lsu.edu

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

"At 23:57:08.96 UT on 04 April 2026, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 260404A (trigger 797039833/260404998).

The on-ground calculated location, using the Fermi GBM trigger data,
is RA = 165.79, Dec = -48.56 (J2000 degrees, equivalent to J2000 11h 03m, -48d 33'),
with a statistical uncertainty of 18.12 degrees.

The angle from the Fermi LAT boresight is 113 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260404998/quicklook/glg_skymap_all_bn260404998.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/bn260404998/quicklook/glg_healpix_all_bn260404998.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260404998/quicklook/glg_lc_medres34_bn260404998.gif"