[vsnet-grb-info 25574] Fermi GBM observation of a flare from the magnetar SGR 1806-20

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  27674
SUBJECT: Fermi GBM observation of a flare from the magnetar SGR 1806-20
DATE:    20/05/01 15:38:19 GMT
FROM:    Christian Malacaria at NASA-MSFC/USRA  <cmalacaria at usra.edu>

C. Malacaria (NASA/MSFC/USRA) reports on behalf of the Fermi GBM Team:

"At 12:56:41 UT on 30 April 2020, the Swift Burst Alert Telescope (BAT) 
triggered and located SGR 1806-20 (GCN 27672).

There was no Fermi-GBM onboard trigger around the event time.
However, the GBM targeted search [1], the most sensitive, coherent search
for sub-threshold signals, was run from +/-5 s around the trigger time, 
and identified a significant signal whose location is consistent with SGR 1806-20.
The search was run down to a timescale of 4 ms and finds the most significant 
timescale at 32 ms, with a log likelihood ratio of 50.

The flare spectrum is well fit by a blackbody model with a best-fit temperature 
value of kT=7.5+/-1.1 keV. The event fluence (8-100 keV)
in this time interval is (1.5 +/- 0.3)E-7 erg/cm^2.

The spectral analysis results presented above are preliminary.

For Fermi GBM data and info, please visit the official Fermi GBM Support Page:
https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/

[1] Goldstein et al. 2019 arXiv:1903.12597"