GCN Circular 45809
GRB 261002A: Fermi GBM Final Localization
From: unknown
Issued: 2026-10-05 15:23 UTC
Type: GRB, Gamma-ray Transient
Why this event is posted: every one of the gamma-ray bursts is posted.
The Fermi GBM team reports the detection of a likely LONG GRB.
"At 20:48:03.81 UT on 02 October 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 261002A (trigger 812666888/261002867).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 155.0, Dec = -1.9 (J2000 degrees, equivalent to J2000 10h 20m, -1d 54'), with a statistical uncertainty of 5.5 degrees.
The angle from the Fermi LAT boresight is 83 degrees.
The skymap can be found here: 
The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn261002867/quicklook/glg_healpix_all_bn261002867.fit
The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn261002867/quicklook/glg_lc_medres34_bn261002867.gif";
Every one of the gamma-ray bursts GCN reports is posted here.
Relayed automatically from NASA's General Coordinates Network.
In plain words Routine
NASA's Fermi space telescope detected a burst of gamma rays (the most energetic form of light) on 2 October 2026 at about 20:48 UT. It came from the direction of the constellation region near 10h 20m right ascension and about 2 degrees south of the celestial equator. The position is only rough, uncertain by about 5.5 degrees, which is roughly the width of a few fingers held at arm's length. The Fermi team classes it as a likely long gamma-ray burst, the kind usually linked to the collapse of a massive star. No distance, afterglow or follow-up observations are reported yet.
How unusual is it? This is one of the few hundred gamma-ray bursts Fermi and Swift catch each year, with only an initial rough location and no distance or counterpart reported. A measured distance or a found afterglow in other light would make it notable.
Written by an AI model (claude-sonnet-5-5) from the official reports in this thread; last updated . It may contain mistakes: the reports themselves are the authority.
GRB 261002A — GRB, Gamma-ray Transient