GCN Circular 46007
Subject
GRB 261021A: Fermi GBM Final Real-time Localization
Event
Date
2026-10-21T19:03:40Z (19 hours 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 LONG GRB
At 18:53:09 UT on 21 Oct 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 261021A (trigger 814301594.113176 / 261021787).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 245.7, Dec = 42.9 (J2000 degrees, equivalent to J2000 16h 22m, 42d 53'), with a statistical uncertainty of 6.1 degrees.
The angle from the Fermi LAT boresight is 119.0 degrees.
The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn261021787/quicklook/glg_skymap_all_bn261021787.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/bn261021787/quicklook/glg_healpix_all_bn261021787.fit
The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn261021787/quicklook/glg_lc_medres34_bn261021787.gif