[vsnet-grb-info 19415] Konus-Wind observation of GRB 170522B

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  21131
SUBJECT: Konus-Wind observation of GRB 170522B
DATE:    17/05/23 14:58:06 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/intense GRB 170522B (IPN triangulation:
Hurley et al., GCN 21130) triggered Konus-Wind
at T0=84124.494 s UT (23:22:04.494)

The burst light curve shows a weak count rate increase (from
~T0-187s to ~T0-167s) followed by a bright, multi-peaked pulse
which started at ~T0-30 s an had a total duration of ~87 s.
The emission is seen up to ~10 MeV.

As observed by Konus-Wind, the burst had a fluence of
(1.75 ± 0.11)x10^-4 erg/cm2 and a 64-ms peak energy flux,
measured from T0+8.640 s of (2.36 ± 0.24)x10^-5 erg/cm2
(both in the 20 keV - 10 MeV energy range).

The time-integrated spectrum (measured from T0 to T0+55.040 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 = -1.16 (-0.05,+0.06),
the high energy photon index beta = -2.15 (-0.09,+0.07),
the peak energy Ep = 252 (-24,+26) keV,
chi2 = 89/97 dof.

The spectrum near the peak count rate (measured from T0+8.448
to T0+9.472 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 = -0.68 (-0.15,+0.16),
the high energy photon index beta = -2.29 (-0.31,+0.16),
the peak energy Ep = 343 (-53,+79) keV,
chi2 = 75/72 dof.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB170522_T84124/

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