GCN Circular 25043

A. Kozlova, S. Golenetskii, R.Aptekar, D. Frederiks,
M. Ulanov, D. Svinkin, A. Tsvetkova, A.Lysenko,
and T. Cline on behalf of the Konus-Wind team, report:

A long GRB was detected by Konus-Wind (KW) in the
waiting mode on July 8, 2019 at ~71160 s UT (19:46:00),
~240 s before the MAXI trigger (GRB 190708B;
Kawakubo et al., GCN 25037
Not found
 
 
).

The burst light curve shows a single pulse
with a duration of ~ 20 s. Taking into account the
proximity of this burst to the MAXI/GSC trigger and
the consistency of the KW ecliptic latitude response with
the position of GRB 190708B we suggest that KW observed
the main part of GRB 190708B.

As observed by KW, the burst had a fluence of
3.44(-0.33,+1.35)x10^-6 erg/cm2 and a 2.944-s peak flux,
measured from ~T0(MAXI)-236.3 s, of 2.54(-0.73,+1.21)x10^-7 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

Modeling the KW 3-channel time-integrated spectrum
(from ~T0(MAXI)-242.2 s to ~T0(MAXI)-221.6 s)
by a simple power-law model yields the power law
index of -2.01(-0.08,+0.16), chi2 = 3.3/1 dof.

Modeling this spectrum by a power law with exponential cutoff model
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with the photon index alpha fixed to -1, yields
Ep = 91.6 (-15.7,+28.7) keV, chi2 = 0.12/1 dof.

The KW light curve of this burst is available at
http://www.ioffe.rssi.ru/LEA/GRBs/GRB190708B

All the quoted errors are estimated at the 1 sigma confidence level.
All the presented results are preliminary.