GCN Circular 29536
Subject
Fermi GBM Sub-Threshold Detection of GRB 210217A
Date
2021-02-18T22:22:40Z (3 years ago)
From
Joshua Wood at MSFC/Fermi-GBM <joshua.r.wood@nasa.gov>
C. Fletcher (USRA) reports on behalf of the Fermi-GBM Team:
Swift-BAT detected GRB 210217A at 23:25:42 UT (GCN 29521). There was no
Fermi-GBM onboard trigger around the event.
An automated, blind search for short gamma-ray bursts below the onboard
triggering threshold in Fermi-GBM identified a high reliability transient
consistent in both time and location with the Swift BAT event.
Link: https://gcn.gsfc.nasa.gov/notices_gbm_sub/635297147.fermi
The GBM targeted search [1], the most sensitive, coherent search for
GRB-like signals also identified a transient most significantly on the 1.024 s
timescale, with a log likelihood ratio of 72 and a location consistent with
the Swift BAT event. The GBM targeted search event was found with the highest
significance with a "normal" spectrum (Band function with
Epeak = 230 keV, alpha = -1.0, beta = -2.3) for a GRB.
[1] Goldstein et al. 2019 arXiv:1903.12597