TITLE:   GCN CIRCULAR
NUMBER:  39001
SUBJECT: Konus-Wind detection of GRB 250117A
DATE:    25/01/20 16:32:53 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 short-duration GRB 250117A
(GECAM-B detection: Wang et al., GCN 38982;
Swift/BAT-GUANO localization: DeLaunay et al., GCN 38988;
SVOM/GRM detection: Wang et al., GCN 38994;
IPN triangulation: Ridnaia et al., GCN 39000)
triggered Konus-Wind at T0=73313.657 s UT (20:21:53.657).

The burst light curve shows a weak count rate increase (from
~T0-0.412 s to ~T0-0.288) followed by a bright, multi-peaked pulse,
which starts at ~T0-0.126 s and has a duration of ~0.138 s.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB250117_T73313/

As observed by Konus-Wind, the burst had
the total fluence of 7.70(-0.02,+2.44)x10^-7 erg/cm^2
and a 16-ms peak flux, measured from T0-0.008 s,
of 1.87(-0.25,+0.64)x10^-5 erg/cm^2/s
(both in the 20 keV - 10 MeV energy range).

Since a major part of the burst emission
was detected before the trigger time, the spectral analysis
was performed using the KW 3-channel light curve data.

Modelling the KW 3-channel spectrum of the main pulse
(measured from T0-0.126 s to T0+0.012 s)
by a power law with exponential cutoff (CPL) model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep),
yields alpha = 0.52 (-0.54, + 0.75) and Ep = 459(-62,+84) keV.

All the quoted errors are estimated at the 68% confidence level.
All the presented results are preliminary.