STARITHM
Fermi GBM detected a Terrestrial Gamma-ray Flash (TGF) on 2026-09-29
AI Summary
Fermi GBM triggered on event 812352027 at 05:20:22.41 UTC, classified with 100% confidence as a Terrestrial Gamma-ray Flash (TGF) rather than a cosmological GRB. The burst had a duration of 16 ms with a significance of 5.2-6.2 sigma and intensity of 1002 counts, detected across energy channels from 291 keV to infinity. TGFs are atmospheric phenomena of non-astrophysical origin, originating from thunderstorm activity in Earth's upper atmosphere rather than distant cosmic sources.
Measurements
| Event ID | 812352027 |
|---|---|
| Source | Fermi GBM |
| Alert type | GRB |
| Significance | low |
| Trigger time (UTC) | Tue, 29 Sep 2026 05:20:22 GMT |
| Right ascension (J2000) | 242.0167° |
| Declination (J2000) | -47.2667° |
| Position error radius | 25.2333° |
| GCN notices | 2 |
| GCN circulars | 0 |
Notices (1)
Fermi GBM — GRB · Tue, 29 Sep 2026 05:20:22 GMT
AI summary generated Tue, 29 Sep 2026 07:19:06 GMT.