[vsnet-grb-info 20451] Konus-Wind observation of GRB 180324A

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  22547
SUBJECT: Konus-Wind observation of GRB 180324A
DATE:    18/03/26 13:27:09 GMT
FROM:    Dmitry Frederiks at Ioffe Institute  <fred at mail.ioffe.ru>

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

GRB 180324A (Swift-BAT trigger 817345:
Sonbas et al., GCN 22524; Krimm et al., GCN 22533)
triggered Konus-Wind at T0=16629.939 s UT (04:37:09.939)

The burst light curve shows a weak pulse,
which started at ~T0-0.4 s and peaked at ~T0 s.
The total duration of the burst is ~0.7 s.
The emission is seen up to ~0.5 MeV.

As observed by Konus-Wind, the burst had a fluence of
(7.4 ± 2.1)x10^-7 erg/cm2 and a 64-ms peak energy flux,
measured from T0, of (1.8 ± 0.5)x10^-6 erg/cm2
(both in the 20 keV - 10 MeV energy range).

The burst spectrum (measured from T0 to T0+0.256 s)
is best fit in the 20 keV - 15 MeV range by a cutoff power-law
(CPL) function with the following model parameters:
the photon index alpha = -0.56(-0.71,+1.16),
and the peak energy Ep = 154(-38,+77) keV,
chi2 = 22/19 dof.
Fitting this spectrum with the GRB (Band) function yields
the same alpha and Ep, and an upper limit on beta of ~-2.2

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB180324_T16629/

All the quoted errors are estimated at the 90% confidence level.
All the presented results are preliminary.