TITLE:   GCN CIRCULAR
NUMBER:  35603
SUBJECT: Konus-Wind detection of GRB 240112A
DATE:    24/01/23 11:56:59 GMT
FROM:    Anna Ridnaia at Ioffe Institute <ridnaia@mail.ioffe.ru>

A. Ridnaia, D. Frederiks, A. Lysenko, D. Svinkin,
A. Tsvetkova,  M. Ulanov, and T. Cline,
on behalf of the Konus-Wind team, report:

The long-duration GRB 240112A
(GECAM-B detection: Wang and Xiong, GCN 35520;
IPN triangulation: Kozyrev et al., GCN 35554)
triggered Konus-Wind at T0=20481.732 s UT (05:41:21.732).

The burst light curve shows the main multi-peaked episode,
which starts at ~T0-0.2 s and has a total duration of ~2.8 s.
A fainter broad pulse is observed in the KW data from ~T0+113 s
to ~T0+120 s after the main pulse, whose association with
GRB 240112A is supported by the consistent KW ecliptic
latitude response. 

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB240112_T20481/

As observed by Konus-Wind, the burst (main episode)
had a fluence of 7.58(-1.05,+1.13)x10^-6 erg/cm2,
and a 64-ms peak flux, measured from T0+1.376 s,
of 1.03(-0.19,+0.20)x10^-5 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The spectrum of the main episode
(measured from T0 to T0+8.448 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 = -1.04(-0.21,+0.23),
the high energy photon index beta = -2.67(-0.73,+0.26),
the peak energy Ep = 120(-15,+20) keV
(chi2 = 118/75 dof).

The spectrum of the fainter broad pulse
(measured from T0+106.752 to T0+123.136 s)
is best fit in the 20 keV - 10 MeV range
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with  alpha = -1.67(-0.32,+0.53)
and Ep = 206(-195,+1360) keV (chi2 = 71/86 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta < -2.0
(chi2 = 71/85 dof).

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