STARITHM
Fermi GBM detected long GRB 260921B on 2026-09-21 at 21:44:37 UT
AI Summary
Fermi GBM triggered on a likely long gamma-ray burst (GRB 260921B) with trigger ID 811719882 on September 21, 2026. The burst was localized to RA = 62.12°, Dec = 31.21° (J2000) with a statistical uncertainty of 2.22 degrees and detected in the energy range 44-280 keV. Ground-based analysis confirmed the localization with burst significance of 24.6 sigma over a 2.048 second timescale, though some flight-based classifiers suggested AGN contamination (59-82% probability), indicating possible source confusion at the initial detection stage.
Measurements
| Event ID | 811719882 |
|---|---|
| Source | Fermi GBM |
| Alert type | GRB |
| Significance | high |
| Trigger time (UTC) | Mon, 21 Sep 2026 21:44:37 GMT |
| Right ascension (J2000) | 62.12° |
| Declination (J2000) | 31.21° |
| Position error radius | 2.22° |
| GCN notices | 7 |
| GCN circulars | 1 |
Notices (1)
Fermi GBM — GRB · Mon, 21 Sep 2026 21:44:37 GMT
GCN Circulars (1)
GCN-45685 — GRB 260921B
· Mon, 21 Sep 2026 23:19:25 GMT
The Fermi Gamma-ray Burst Monitor (GBM) detected a likely long gamma-ray burst (GRB 260921B) on September 21, 2026, at 21:44:37.15 UT. The event was localized to RA = 62.12, Dec = 31.21 (J2000) with a statistical uncertainty of 2.22 degrees.
AI summary generated Tue, 22 Sep 2026 00:03:02 GMT.