TITLE:   GCN CIRCULAR
NUMBER:  43579
SUBJECT: GRB 260131A: Fermi GBM Final Real-time Localization
DATE:    26/01/31 06:50:08 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 06:39:30 UT on 31 Jan 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260131A (trigger 791534375.436908 / 260131277).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 21.9, Dec = 26.9 (J2000 degrees, equivalent to J2000 01h 27m, 26d 53'), with a statistical uncertainty of 1.8 degrees.

The angle from the Fermi LAT boresight is 104.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260131277/quicklook/glg_skymap_all_bn260131277.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/bn260131277/quicklook/glg_healpix_all_bn260131277.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260131277/quicklook/glg_lc_medres34_bn260131277.gif