[vsnet-grb-info 21684] Konus-Wind observation of GRB 190122A

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  23783
SUBJECT: Konus-Wind observation of GRB 190122A
DATE:    19/01/24 14:34:28 GMT
FROM:    Dmitry Svinkin at Ioffe Institute  <svinkin at mail.ioffe.ru>

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

The long-duration GRB 190122A
(Fermi-LAT detection: Longo et al., GCN Circ. 23767;
Fermi-GBM detection: Bissaldi et al., GCN Circ. 23768)
triggered Konus-Wind at T0=26347.426 s UT (07:19:07.426).

The burst light curve shows a FRED-like pulse
which starts at ~T0-0.4 s and has a total duration of ~67 s.
The emission is seen up to ~6 MeV.

As observed by Konus-Wind, the burst
had a fluence of 3.52(-0.74,+0.85)x10^-5 erg/cm2,
and a 64-ms peak flux, measured from T0-0.046 s,
of 3.77(-1.47,+3.90)x10^-6 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-averaged spectrum of the burst
(measured from T0 to T0+73.984 s)
is best fit in the 20 keV - 15 MeV range
by a simple power-law function with the
photon index = -1.58(-0.08,+0.08), chi2 = 80/99 dof.
Fitting by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
yields alpha = -1.48(-0.12,+0.16)
and only an upper limit on Ep: Ep > 560 keV
(chi2 = 76/98 dof).

The spectrum near the maximum count rate
(measured from T0 to T0+8.448 s)
is best fit in the 20 keV - 15 MeV range
by a power law with exponential cutoff model:
with  alpha = -1.43(-0.16,+0.17)
and Ep = 718(-337,+7104) keV (chi2 = 99/98 dof).

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB190122_T26347/

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