TITLE:   GCN CIRCULAR
NUMBER:  43356
SUBJECT: GRB 260109A: Fermi GBM Final Real-time Localization
DATE:    26/01/09 03:55:04 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 03:44:24 UT on 9 Jan 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260109A (trigger 789623069.789512 / 260109156).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 307.3, Dec = -69.0 (J2000 degrees, equivalent to J2000 20h 29m, -69d 00'), with a statistical uncertainty of 8.0 degrees.

The angle from the Fermi LAT boresight is 90.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260109156/quicklook/glg_skymap_all_bn260109156.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/bn260109156/quicklook/glg_healpix_all_bn260109156.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260109156/quicklook/glg_lc_medres34_bn260109156.gif