[vsnet-grb-info 22039] Konus-Wind observation of GRB 190415A

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  24138
SUBJECT: Konus-Wind observation of GRB 190415A
DATE:    19/04/21 18:33:57 GMT
FROM:    Dmitry Frederiks at Ioffe Institute  <fred at mail.ioffe.ru>

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

The long GRB 190415A (Insight-HXMT/HE detection: Luo et al.,
GCN 24125; IPN triangulation: Svinkin et al., GCN 24128)
triggered Konus-Wind (KW) at T0=14986.024 s UT (04:09:46.024).

The light curve of the burst shows a bright, hard-spectrum,
multi-peaked pulse, which started at ~T0 s and had a duration of ~ 19s. 
This pulse was followed by a weaker and softer emission tail
of the emission detectable until ~T0+57 s.
The emission is seen up to ~2 MeV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB190415_T14986/

As observed by Konus-Wind, the burst had
a fluence of (8.8 ± 0.8)x10^-5 erg/cm2 and
a 64-ms peak energy flux, measured from T0+5.824,
of (2.33 ± 0.14)x10^-5 erg/cm2 (both in the 20 keV - 10 MeV
energy range).

The time-integrated spectrum (measured from T0 to T0+56.512 s)
is best fit in the 20 keV - 15 MeV range by a cutoff power-law
(CPL) function with the following model parameters:
the photon index alpha = -0.65(-0.10,+0.11),
and the peak energy Ep = 892(-99,+120) keV,
chi2 = 94/98 dof.
Fitting this spectrum with the GRB (Band) function yields
the same alpha and Ep, and an upper limit on beta (-3.1).

The spectrum near the peak count rate (measured from T0 to T0+7.360)
is best fit in the 20 keV - 15 MeV range by
the CPL function with the following model parameters:
the photon index alpha = -0.17(-0.09,+0.10),
and the peak energy Ep = 994(-62,+67) keV,
chi2 = 89/98 dof.
Fitting this spectrum with the GRB (Band) function yields
the same alpha and Ep, and an upper limit on beta (-3.8).

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