TITLE: GCN CIRCULAR NUMBER: 38881 SUBJECT: Konus-Wind detection of GRB 250107D (short/hard) DATE: 25/01/09 22:08:34 GMT FROM: Dmitry Frederiks at Ioffe Institute fred@mail.ioffe.ru

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

The short GRB 250107D (IPN triangulation: Kozyrev et al., GCN 38880) triggered Konus-Wind (KW) at T0=19411.897 s UT (05:23:31.897).

The burst light curve shows a single, multi-peaked emission pulse which starts at ~T0-0.112 s and has a duration of ~0.208 s.

The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB250107_T19411/

As observed by Konus-Wind, the burst had the total fluence of 2.06(-0.34,+0.62)x10^-6 erg/cm^2 and a 16-ms peak energy flux, measured from T0-0.064 s, of 1.99(-0.32,+0.59)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 time-averaged spectral analysis was performed using the KW 3-channel light curve data. Modeling the 3-channel time-integrated spectrum (measured from T0-0.112 s to T0+0.096 s) by a power law with exponential cutoff (CPL) model dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep) yields alpha = -0.40 (-0.32, + 0.41) and Ep = 897(-203,+453) keV.

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

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