[vsnet-grb-info 19154] Konus-Wind observation of GRB 170222A

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  20731
SUBJECT: Konus-Wind observation of GRB 170222A
DATE:    17/02/24 12:52:25 GMT
FROM:    Anna Kozlova at Ioffe Institute  <ann_kozlova at mail.ioffe.ru>

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

The short-duration GRB 170222A
(IPN triangulation: Hurley et al., GCN 20722;
Fermi GBM observation: Hamburg et al., GCN 20728)
triggered Konus-Wind at T0=18056.528 s UT (05:00:56.528).

The burst light curve shows a multi-peaked structure
which starts at ~T0-0.1 s and has a total duration of ~1.9 s.
The emission is seen up to ~10 MeV.

As observed by Konus-Wind, the burst had a fluence of
9.10(-2.43,+3.61)x10^-6 erg/cm2, and a 64-ms peak flux,
measured from T0+1.104 s, of 1.23(-0.46,+0.76)x10^-5 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 - 10 MeV range
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with  alpha = -0.72(-0.26,+0.36)
and Ep = 1210(-418,+830) keV (chi2 = 73/88 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta < -2.28
(chi2 = 73/87 dof)

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB170222_T18056/

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