TITLE:   GCN CIRCULAR
NUMBER:  29388
SUBJECT: Fermi GBM Observations of a bright burst from SGR J1935+2154
DATE:    21/02/03 17:20:33 GMT
FROM:    Elisabetta Bissaldi at INFN,Bari  <elisabetta.bissaldi@ba.infn.it>

E. Bissaldi (Politecnico and INFN Bari)
reports on behalf of the Fermi GBM Team:


"At 12:54:27.00 UT on 2 February 2021, the Fermi Gamma-Ray Burst Monitor (GBM)
triggered and located a burst from SGR J1935+2154 (trigger 633963272/210202538).
The same burst was also reported by INTEGRAL (Ricciarini et al. 2021, GCN 29383).

The GBM on-ground location is consistent with the known position of the SGR.

The angle from the Fermi LAT boresight at the GBM trigger time is 90 degrees.

The burst has a duration (T90) of about 0.1 seconds
in the energy range 10-200 keV.

The time-averaged spectrum from T0-0.048 s to T0+0.96 s is
adequately fit by a power law function with an exponential
high-energy cutoff.  The power law index is 0.28 +/- 0.13 and
the cutoff energy, parameterized as Epeak, is 34.1 +/- 0.6 keV.

The event fluence (10-1000 keV) in this time interval is
(8.25 +/- 0.14)E-07 erg/cm^2.
The 64-ms peak photon flux measured starting from T0
in the 10-1000 keV band is 152 +/- 5 ph/s/cm^2.

The spectral analysis results presented above are preliminary.

GBM will continue to monitor the source and issue GCNs for bright bursts
from SGR J1935+2154 that have been observed by other instruments
with improved localizing capabilities, and for SGR bursts
initially misclassified as GRBs.


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