[vsnet-grb-info 16360] Konus-Wind observation of GRB 150323B

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  17641
SUBJECT: Konus-Wind observation of GRB 150323B
DATE:    15/03/25 16:39:15 GMT
FROM:    Anastasia Tsvetkova at Ioffe Institute  <tsvetkova 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 long-duration GRB 150323B
(Swift-BAT trigger #635929: Cummings, GCN 17619;
Fermi-GBM observation: von Kienlin, GCN 17623)
triggered Konus-Wind at T0=34121.196 s UT (09:28:41.196).

The burst light curve shows several bright peaks during first ~60 s 
after the trigger.
In the instrument's soft energy channel, the flaring can be traced up to 
~T0+150 s.

As observed by Konus-Wind, the burst
had a fluence of 2.0(-0.1,+0.2)x10^-5 erg/cm2,
and a 64-ms peak energy flux, measured from T0+22.656 s,
of 1.4(-0.6,+0.6)x10^-6 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-integrated spectrum of the burst
(measured from T0 to T0+65.792 s)
is best fit in the 20 keV - 15 MeV range
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with  alpha = -1.53(-0.10,+0.11),
and Ep = 109(-12,+15) keV (chi2 = 109/98 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index:
beta < -2.90 (chi2 = 109/97 dof).

The spectrum near the peak count rate
(measured from T0+16.640 to T0+24.832 s)
is best fit in the 20 keV - 1 MeV range
by the power law with exponential cutoff model
with  alpha = -1.15(-0.25,+0.29),
and Ep = 215(-51,+108) keV (chi2 = 35/59 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index:
beta < -1.97 (chi2 = 35/58 dof).

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB150323_T34121/

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