TITLE:   GCN CIRCULAR
NUMBER:  43951
SUBJECT: GRB 260310A: Fermi GBM Final Real-time Localization
DATE:    26/03/10 05:07:50 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 04:57:10 UT on 10 Mar 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260310A (trigger 794811435.80987 / 260310206).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 213.6, Dec = 78.7 (J2000 degrees, equivalent to J2000 14h 14m, 78d 42'), with a statistical uncertainty of 4.3 degrees.

The angle from the Fermi LAT boresight is 124.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260310206/quicklook/glg_skymap_all_bn260310206.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/bn260310206/quicklook/glg_healpix_all_bn260310206.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260310206/quicklook/glg_lc_medres34_bn260310206.gif