TITLE:   GCN CIRCULAR
NUMBER:  33544
SUBJECT: Konus-Wind detection of GRB 230328B
DATE:    23/03/30 14:13:25 GMT
FROM:    Dmitry Svinkin at Ioffe Institute  <svinkin@mail.ioffe.ru>

D. Svinkin, D. Frederiks, M. Ulanov, A. Tsvetkova,
A. Lysenko, A. Ridnaia, and T. Cline
on behalf of the Konus-Wind team, report:

The long-duration GRB 230328B
(Fermi-GBM detection: The Fermi GBM team, GCN Circ. 33526;
Swift-BAT detection: Gropp et al., GCN Circ. 33527;
Markwardt et al., GCN Circ. 33541;
AstroSat-CZTI detection: Waratkar et al., GCN Circ. 33532;
GRBAlpha detection: Dafcikova et al., GCN Circ. 33543;)
triggered Konus-Wind at T0=53688.873 s UT (14:54:48.873).

The burst light curve shows a multi-peaked structure
which starts at ~T0-3.3 s and has a total duration of ~12 s.
The emission is seen up to ~2 MeV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB230328_T53688/

As observed by Konus-Wind, the burst
had a fluence of 7.12(-0.51,+0.58)x10^-6 erg/cm2,
and a 64-ms peak flux, measured from T0+0.430 s,
of 2.87(-0.77,+0.78)x10^-6 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-averaged spectrum of the burst
(measured from T0 to T0+8.448 s)
is best fit in the 20 keV - 5 MeV range
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with  alpha = -1.38(-0.13,+0.14)
and Ep = 151(-21,+29) keV (chi2 = 73/75 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta < -2.2
(chi2 = 74/24 dof).

All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.