TITLE:   GCN CIRCULAR
NUMBER:  43335
SUBJECT: GRB 260105A: Fermi GBM Final Real-time Localization
DATE:    26/01/05 22:57:42 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 22:47:11 UT on 5 Jan 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260105A (trigger 789346036.667754 / 260105949).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 64.5, Dec = 55.5 (J2000 degrees, equivalent to J2000 04h 17m, 55d 30'), with a statistical uncertainty of 3.3 degrees.

The angle from the Fermi LAT boresight is 99.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260105949/quicklook/glg_skymap_all_bn260105949.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/bn260105949/quicklook/glg_healpix_all_bn260105949.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260105949/quicklook/glg_lc_medres34_bn260105949.gif