GCN Circular 30838
Subject
Konus-Wind observation of the recent SGR 1935+2154 activity
Date
2021-09-13T17:56:37Z (3 years ago)
From
Anna Ridnaia at Ioffe Institute <ridnaia@mail.ioffe.ru>
A. Ridnaia, S. Golenetskii, D. Frederiks, M. Ulanov,
D. Svinkin, A. Tsvetkova, A. Lysenko, and T. Cline
on behalf of the Konus-Wind team, report:
Since the last KW GCN on the ongoing SGR 1935+2154 activity
(Ridnaia et al., GCN 30803) the instrument triggered on
four bright bursts from the source.
The following is a list of the Konus-Wind triggers with preliminary
estimates of the burst fluences and peak fluxes.
------------------------------------------------------------------
# Date T0(KW) s UT Fl* PF**
------------------------------------------------------------------
1 20210911 54406.825 s UT(15:06:46.825) 5.38 +/-0.15 22.6 +/-1.6
2 20210911 61274.025 s UT(17:01:14.025) 7.84 +/-0.21 18.5 +/-1.4
3 20210912 24677.185 s UT(06:51:17.185) 4.96 +/-0.14 26.6 +/-1.7
4 20210912 28904.121 s UT(08:01:44.121) 1.25 +/-0.02 17.0 +/-1.4
------------------------------------------------------------------
* - Fluence (20-500 keV) in units of 1e-6 erg/cm2
** - Peak Flux (20-500 keV) on 16-ms time scale
in units of 1e-6 erg/cm2/s
The time-averaged spectra of the bursts are well fit in the
20 - 200 keV range by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep) with the following parameters:
------------------------------------------------------------------
# T100 Tbeg-Tend alpha Ep(keV) chi2/dof
------------------------------------------------------------------
1 0.392 0 - 0.256 0.47(-0.32,+0.33) 42(-2,+2) 30/20
2 1.243 0 - 8.448 0.40(-0.37,+0.39) 37(-2,+1) 36/28
3 0.452 0 - 0.256 0.20(-0.35,+0.37) 38(-2,+2) 17/19
4 1.600 0 - 8.448 -0.10(-0.21,+0.22) 35(-1,+1) 43/29
------------------------------------------------------------------
The emission in all bursts is seen up to ~200 keV.
The Konus-Wind light curves of the bursts are available at
http://www.ioffe.ru/LEA/SGRs/210911_T54406/
http://www.ioffe.ru/LEA/SGRs/210911_T61274/
http://www.ioffe.ru/LEA/SGRs/210912_T24677/
http://www.ioffe.ru/LEA/SGRs/210912_T28904/
All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.