TITLE:   GCN CIRCULAR
NUMBER:  44812
SUBJECT: GRB 260604A: Fermi GBM Final Real-time Localization
DATE:    26/06/04 02:36:52 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 02:24:27 UT on 4 Jun 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260604A (trigger 802232672.54125 / 260604100).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 60.4, Dec = -12.8 (J2000 degrees, equivalent to J2000 04h 01m, -12d 48'), with a statistical uncertainty of 9.3 degrees.

The angle from the Fermi LAT boresight is 94.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260604100/quicklook/glg_skymap_all_bn260604100.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/bn260604100/quicklook/glg_healpix_all_bn260604100.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260604100/quicklook/glg_lc_medres34_bn260604100.gif