TITLE:   GCN CIRCULAR
NUMBER:  41993
SUBJECT: GRB 250926A: Fermi GBM Final Real-time Localization
DATE:    25/09/26 00:31:52 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 00:21:23 UT on 26 Sep 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250926A (trigger 780538888.96614 / 250926015).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 83.0, Dec = -7.0 (J2000 degrees, equivalent to J2000 05h 31m, -7d 00'), with a statistical uncertainty of 1.8 degrees.

The angle from the Fermi LAT boresight is 79.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250926015/quicklook/glg_skymap_all_bn250926015.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250926015/quicklook/glg_healpix_all_bn250926015.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250926015/quicklook/glg_lc_medres34_bn250926015.gif