[vsnet-grb-info 16471] Konus-Wind observation of GRB 150424A

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  17752
SUBJECT: Konus-Wind observation of GRB 150424A
DATE:    15/04/24 16:56:48 GMT
FROM:    Dmitry Svinkin at Ioffe Institute  <svinkin at mail.ioffe.ru>

S. Golenetskii, R. Aptekar, D. Frederiks, V. Pal'shin, P. Oleynik,
M. Ulanov, D. Svinkin, A. Tsvetkova, A. Lysenko, and T. Cline
on behalf of the Konus-Wind team, report:

The short-duration, intense GRB 150424A
(Swift/BAT detection: Beardmore et al., GCN Circ. 17743).
triggered Konus-Wind at T0=27781.073 s UT (07:43:01.073).

The burst light curve shows a multipeak structure
with a total duration of ~0.4 s.
The emission is seen up to 4 MeV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB150424_T27781/

As observed by Konus-Wind, the burst
had a fluence of 1.81(-0.11,+0.11)x10^-5 erg/cm2,
and a 2-ms peak flux, measured from T0+0.212 s,
of 1.85(-0.48,+0.48)x10^-4 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-averaged spectrum of the burst
(measured from T0 to T0+0.256 s)
is best fit in the 20 keV - 10 MeV range
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with  alpha = -0.37(-0.09,+0.10)
and Ep = 919(-76,+82) keV (chi2 = 66/57 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta < -3.8
(chi2 = 66/56 dof)

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