GCN Circular 46075
Subject
GRB 261029B: Fermi GBM Final Real-time Localization
Event
Date
2026-10-29T02:34:51Z (4 days ago)
From
Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply@GIOC.nsstc.nasa.gov>
Via
email
The Fermi GBM team reports the detection of a likely SHORT GRB
At 02:24:10 UT on 29 Oct 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 261029B (trigger 814933455.723852 / 261029100).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 48.5, Dec = 4.3 (J2000 degrees, equivalent to J2000 03h 14m, 4d 17'), with a statistical uncertainty of 9.4 degrees.
The angle from the Fermi LAT boresight is 71.0 degrees.
The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn261029100/quicklook/glg_skymap_all_bn261029100.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/bn261029100/quicklook/glg_healpix_all_bn261029100.fit
The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn261029100/quicklook/glg_lc_medres34_bn261029100.gif