[vsnet-grb-info 22353] Konus-Wind observation of GRB 190501A

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  24452
SUBJECT: Konus-Wind observation of GRB 190501A
DATE:    19/05/10 12:50:16 GMT
FROM:    Anastasia Tsvetkova at Ioffe Institute  <tsvetkova at mail.ioffe.ru>

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

The long-duration, bright GRB 190501A
(AGILE/MCAL and scientific ratemeters detection:
Ursi  et al., GCN 24360;
AGILE/GRID detection: Lucarelli et al., GCN 24361;
Verrecchia et al., GCN 24363;
IPN Triangulation: Hurley et al., GCN 24372;
CALET Gamma-Ray Burst Monitor detection: Ricciarini t al., GCN 24406)
triggered Konus-Wind at T0=19401.146 s UT (05:23:21.146).

The burst light curve shows a bright, multi-peaked pulse with a duration 
of ~50 s
followed by a weak tail up to 137 s.
The emission is seen up  to ~1200 keV,  no KW data above 1.2 MeV are
available at the time of writing.

As observed by Konus-Wind, the burst
had a fluence of 2.04(-0.13,+0.13)x10^-4 erg/cm2,
and a 64-ms peak energy flux, measured from T0+4.272 s,
of 3.55(-0.99,+0.99)x10^-5 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-integrated spectrum of the burst
(measured from T0 to T0+22.784 s)
is best fit in the 20 keV - 1.2 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.91(-0.04,+0.04),
the high energy photon index beta = -2.10(-0.09,+0.08),
the peak energy Ep = 316(-23,+24) keV,
chi2 = 70/59 dof.

The spectrum near the peak count rate
(measured from T0+3.840 to T0+4.352 s)
is best fit in the 20 keV - 1.2 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.65(-0.11,+0.14),
the high energy photon index beta = -2.28(-1.52,+0.31),
the peak energy Ep = 410(-72,+77) keV,
chi2 = 53/47 dof.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB190501_T19401/

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