[vsnet-grb-info 27433] Fermi GBM Sub-Threshold Detection of GRB 210217A

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  29536
SUBJECT: Fermi GBM Sub-Threshold Detection of GRB 210217A
DATE:    21/02/18 22:22:40 GMT
FROM:    Joshua Wood at MSFC/Fermi-GBM  <joshua.r.wood at 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