GCN Circular 45788
GRB 260930A: Fermi GBM Final Real-time Localization
From: Fermi GBM Team at MSFC/Fermi-GBM
Issued: 2026-09-30 20:09 UTC
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 19:59:09 UT on 30 Sep 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260930A (trigger 812491154.688938 / 260930833).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 175.2, Dec = -7.3 (J2000 degrees, equivalent to J2000 11h 40m, -7d 17'), with a statistical uncertainty of 8.1 degrees.
The angle from the Fermi LAT boresight is 61.0 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/bn260930833/quicklook/glg_healpix_all_bn260930833.fit
The GBM light curve can be found here:
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 Gamma-ray Burst Monitor, a space telescope that watches the whole sky for flashes of high-energy light, detected a gamma-ray burst on 30 September 2026. The flash is likely a 'long' burst, the kind that usually comes from a massive star collapsing. It came from a patch of sky in the constellation region around 11h 40m right ascension and about 7 degrees south of the celestial equator. That position is only rough, uncertain by about 8 degrees, which is roughly the width of a fist held at arm's length. This is the first, automatic report, and it says nothing yet about distance, brightness or any afterglow seen by other telescopes.
How unusual is it? Fermi and Swift together report a few hundred gamma-ray bursts a year, and this is a typical long burst with only a coarse position and no distance or counterpart reported. A measured distance or an afterglow found in other light would raise it to 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 260930A