GCN Circular 29315

Subject
Konus-Wind detection of GRB 210112A
Event
Date
2021-01-17T23:28:52Z (5 years ago)
From
Dmitry Svinkin at Ioffe Institute <svinkin@mail.ioffe.ru>
D. Svinkin, S. Golenetskii, D. Frederiks, M. Ulanov,
A. Tsvetkova, A. Lysenko, A. Ridnaia, and T. Cline
on behalf of the Konus-Wind team, report:

The long-duration GRB 210112A
(Swift-BAT detection: Ambrosi et al., GCN Circ. 29289Loading...
 
 ;
AGILE detection: Ursi et al., GCN Circ. 29293Loading...
 
 )
triggered Konus-Wind at T0=5886.553 s UT (01:38:06.553).

The burst light curve shows a multipeaked structure
which starts at ~T0-73 s and has a total duration of ~143 s.
The emission is seen up to ~5 MeV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB210112_T05886

As observed by Konus-Wind, the burst
had a fluence of 6.72(-0.65,+0.72)x10^-5 erg/cm2,
and a 64-ms peak flux, measured from T0+7.856 s,
of 1.02(-0.18,+0.19)x10^-5 erg/cm2/s
(both in the 20 keV - 16 MeV energy range).

The time-averaged spectrum of the burst
(measured from T0 to T0+68.608 s)
is best fit in the 20 keV - 16 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.96(-0.08,+0.08),
the high energy photon index beta = -2.71(-0.53,+0.25),
the peak energy Ep = 214(-16,+18) keV
(chi2 = 87/97 dof).

The spectrum near the maximum count rate
(measured from T0+7.168 s to T0+9.216 s)
is best fit in the 20 keV - 16 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.85(-0.12,+0.13),
the high energy photon index beta = -2.67(-0.57,+0.27),
the peak energy Ep = 219(-25,+28) keV
(chi2 = 38/65 dof).

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