[vsnet-grb-info 19413] Konus-Wind observation of GRB 170522A

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  21129
SUBJECT: Konus-Wind observation of GRB 170522A
DATE:    17/05/23 10:54:42 GMT
FROM:    Dmitry Frederiks at Ioffe Institute  <fred at mail.ioffe.ru>

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

The long GRB 170522A (Fermi-GBM detection: Stanbro & Meegan,
GCN 21126; Fermi-LAT detection: Arimoto & Racusin, GCN 21127)
triggered Konus-Wind at T0=56735.921 s UT (15:45:35.921)

The burst light curve shows a multi-peaked pulse with
a total duration of ~7.4 s.
The emission is seen up to ~10 MeV.

As observed by Konus-Wind, the burst had a fluence of
(3.8 ± 0.4)x10^-5 erg/cm2 and a 64-ms peak energy flux,
measured from T0+2.048 s of (1.41 ± 0.14)x10^-5 erg/cm2
(both in the 20 keV - 10 MeV energy range).

The time-integrated spectrum (measured from T0 to T0+13.568 s)
is best fit in the 20 keV - 15 MeV range
by the GRB (Band) function with the following model parameters:
the low-energy photon index alpha = -0.48 (-0.20,+0.22),
the high energy photon index beta = -2.42 (-0.38,+0.20),
the peak energy Ep = 289 (-37,+49) keV,
chi2 = 97/97 dof.

The spectrum near the peak count rate (measured from T0 to T0+5.376 s)
is best fit in the 20 keV - 15 MeV range
by the GRB (Band) function with the following model parameters:
the low-energy photon index alpha = -0.39 (-0.17,+0.20),
the high energy photon index beta = -2.49 (-0.31,+0.19),
the peak energy Ep = 312 (-36,+42) keV,
chi2 = 88/97 dof.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB170522_T56735/

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