[vsnet-grb-info 21170] Konus-Wind observation of GRB 180923A

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  23269
SUBJECT: Konus-Wind observation of GRB 180923A
DATE:    18/09/25 15:02:50 GMT
FROM:    Anna Kozlova at Ioffe Institute  <ann_kozlova at mail.ioffe.ru>

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:

The long-duration GRB 180923A localized by MAXI/GSC (Maruyama et al., GCN
23257) and observed by CALET (GBM: Penacchioni et al., GCN 23259) was
detected by Konus-Wind (KW) in the waiting mode.

The burst light curve shows two episodes, started at ~T0(MAXI)-19 s
with a total duration of ~ 127 s.

As observed by KW, the burst had a fluence of
5.42(-0.65,+1.26)x10^-6 erg/cm2 and a 2.944-s peak flux,
measured from ~T0(MAXI)+93.3 s, of 3.47(-0.92,+1.15)x10^-7 erg/cm2/s
(both in the 20 - 1000 keV energy range).

Modeling the KW 3-channel time-integrated spectrum
(from ~T0(MAXI)-18.6 s to ~T0(MAXI)+108 s)
by a simple power-law model yields a power law
index of -2.2(-0.2,+0.2), chi2=0.2/1 dof.

The KW light curve of this burst is available at
http://www.ioffe.rssi.ru/LEA/GRBs/GRB180923A

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