TITLE:   GCN CIRCULAR
NUMBER:  43969
SUBJECT: GRB 260312B: Fermi GBM Final Real-time Localization
DATE:    26/03/12 09:57:18 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 09:46:46 UT on 12 Mar 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260312B (trigger 795001611.054834 / 260312407).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 25.9, Dec = -3.9 (J2000 degrees, equivalent to J2000 01h 43m, -3d 53'), with a statistical uncertainty of 1.9 degrees.

The angle from the Fermi LAT boresight is 67.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260312407/quicklook/glg_skymap_all_bn260312407.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/bn260312407/quicklook/glg_healpix_all_bn260312407.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260312407/quicklook/glg_lc_medres34_bn260312407.gif