[vsnet-grb-info 24852] Konus-Wind observation of GRB 200125B

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  26951
SUBJECT: Konus-Wind observation of GRB 200125B
DATE:    20/01/31 16:11:49 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. Ridnaia, and T. Cline
on behalf of the Konus-Wind team, report:

The long-duration, very bright GRB 200125B
(Fermi-GBM observations: The Fermi GBM team, GCN Circ. 26879;
Veres et al., GCN Circ. 26893;
BALROG localization: Biltzinger et al., GCN Circ. 26880;
Insight-HXMT/HE detection: Cai et al., GCN Circ. 26888;
IPN triangulation: Svinkin et al., GCN Circ. 26918)
triggered Konus-Wind at T0=74611.206 s UT (20:43:31.206).

The burst light curve shows a multipeaked structure
which starts at ~T0-0.5 s and has a total duration of ~10 s.
The emission is seen up to ~10 MeV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB200125_T74611/

As observed by Konus-Wind, the burst
had a fluence of 6.01(-0.36,+0.37)x10^-5 erg/cm2,
and a 64-ms peak flux, measured from T0+1.312 s,
of 3.92(-0.44,+0.46)x10^-5 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-averaged spectrum of the burst
(measured from T0 to T0+12.288 s)
is best fit in the 20 keV - 10 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.91(-0.06,+0.07),
the high energy photon index beta = -2.48(-0.15,+0.12),
the peak energy Ep = 211(-15,+16) keV
(chi2 = 98/97 dof).

The spectrum near the maximum count rate
(measured from T0+1.280 to T0+1.536 s)
is best fit in the 20 keV - 4 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.43(-0.14,+0.16),
the high energy photon index beta = -2.64(-0.34,+0.21),
the peak energy Ep = 295(-36,+39) keV
(chi2 = 63/51 dof).

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