TITLE:   GCN CIRCULAR
NUMBER:  43939
SUBJECT: GRB 260307A: Fermi GBM Final Localization
DATE:    26/03/07 13:08:25 GMT
FROM:    A. Holzmann Airasca at University of Trento and INFN Bari <a.holzmannairasca@unitn.it>

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

"At 11:27:59.32 UT on 07 March 2026, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 260307A (trigger 794575684/260307478).

The on-ground calculated location, using the Fermi GBM trigger data,
is RA = 209.07, Dec = 29.03 (J2000 degrees, equivalent to J2000 13h 56m, 29d 01'),
with a statistical uncertainty of 2.88 degrees.

The angle from the Fermi LAT boresight is 77 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260307478/quicklook/glg_skymap_all_bn260307478.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/bn260307478/quicklook/glg_healpix_all_bn260307478.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260307478/quicklook/glg_lc_medres34_bn260307478.gif"