[vsnet-grb-info 23561] Konus-Wind observation of GRB 190829A

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  25660
SUBJECT: Konus-Wind observation of GRB 190829A
DATE:    19/09/04 17:16:45 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 GRB 190829A which triggered Swift/BAT
at T0=T0(BAT)=19:56:44.60 UT
(Swift/BAT detection: Dichiara et al., GCN 25552; Lien et al., GCN 25579;
Fermi GBM detection: Lesage et al., GCN 25575)
was detected by Konus-Wind in the waiting mode.

The burst light curve shows two emission episodes:
the first pulse lasts from ~T0-51.6 s to ~T0-42.8 s,
and the second pulse lasts from ~T0-4.5 s to ~T0+10.2 s.
The total duration of the burst is ~61.8 s.

As observed by Konus-Wind, the burst had a fluence of
1.29(-0.13,-0.15)x10^-5 erg/cm2 and a 2.944-s peak flux,
measured from ~T0(BAT)-1.58 s, of 1.13(-0.11,+0.13)x10^-6 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

Fitting the K-W 3-channel time-integrated spectrum
(from ~T0(BAT)-51.628 s to ~T0(BAT)+10.196 s)
in the 20 keV - 2 MeV range
by a simple power law model yields
the PL index = 2.30(-0.08,+0.09),
chi2 = 0.61 / 1 dof.

Modelling the K-W 3-channel spectrum of the initial pulse
(from ~T0(BAT)-51.628 s to ~T0(BAT)-48.684 s)
in the 20 keV - 2 MeV range
by a power law with exponential cutoff model
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep) yields
alpha = -1.33(-0.23,+0.30),
and Ep =579(-281,+2282) keV.

Assuming the redshift z=0.0785
(Valeev  et al., GCN 25565; De et al., GCN Circ. 25595)
and a standard cosmology model with H_0 = 67.3 km/s/Mpc,
Omega_M = 0.315, and Omega_Lambda = 0.685 (Planck Collaboration, 2014),
we estimate the following rest-frame parameters:
the isotropic energy release E_iso is ~2.0x10^50 erg,
the peak luminosity L_iso is ~1.9x10^49 erg/s,
and the rest-frame peak energy of the initial pulse spectrum,
Ep,z, is ~624 keV.

All the quoted errors are estimated at the 1 sigma confidence level.
All the presented results are preliminary.

The K-W light curve of this burst is available at
http://www.ioffe.rssi.ru/LEA/GRBs/GRB190829A/