GCN Circular 29772
Subject
Konus-Wind detection of GRB 210406A
Date
2021-04-07T17:58:39Z (4 years ago)
From
Anna Ridnaia at Ioffe Institute <ridnaia@mail.ioffe.ru>
A. Ridnaia, D. Frederiks, S. Golenetskii, A. Lysenko, D. Svinkin,
A. Tsvetkova, M. Ulanov, and T. Cline, report:
The long GRB 210406A (INTEGRAL detection,
T0 = T0(IBIS/ISGRI)= 17:11:28 UT: Mereghetti, et al., GCN 29767;
Fermi/GBM detection: Malacaria & Meegan, GCN 29771)
was detected by Konus-Wind (KW) in the waiting mode.
A Bayesian block analysis of the KW waiting mode data in the 20-400 keV band
reveals a >10 sigma count rate increase over background in the interval
from ~T0-0.470 s to ~T0+73.130 s.
As observed by Konus-Wind, the burst had a fluence of
9.13(-1.16,+1.40)x10^-6 erg/cm2 and a 2.944-s peak flux,
measured in the interval starting from ~T0+5.418 s,
of 5.74(-0.84,+0.97)x10^-7 erg/cm2/s
(both in the 10 keV - 10 MeV energy range).
Modeling the K-W 3-channel time-integrated spectrum
(from ~T0-0.470 s to ~T0+73.130 s)
by a power law with exponential cutoff (CPL) model
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
yields alpha = -1.04(-0.20,+0.35) and Ep = 176(-36,+54) keV.
The KW light curve of this burst is available at
http://www.ioffe.ru/LEA/GRBs/GRB210406A/
All the quoted errors are estimated at the 1 sigma confidence level.
All the presented results are preliminary.