TITLE:   GCN CIRCULAR
NUMBER:  45797
SUBJECT: GRB 261003A: Fermi GBM Final Real-time Localization
DATE:    26/10/03 01:29:04 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 SHORT GRB

At 01:18:35 UT on 3 Oct 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 261003A (trigger 812683120.140818 / 261003055).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 306.5, Dec = 45.7 (J2000 degrees, equivalent to J2000 20h 26m, 45d 42'), with a statistical uncertainty of 20.7 degrees.

The angle from the Fermi LAT boresight is 87.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn261003055/quicklook/glg_skymap_all_bn261003055.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/bn261003055/quicklook/glg_healpix_all_bn261003055.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn261003055/quicklook/glg_lc_medres34_bn261003055.gif