TITLE: GCN CIRCULAR NUMBER: 35658 SUBJECT: Konus-Wind detection of GRB 240123C DATE: 24/02/02 15:53:58 GMT FROM: Alexandra Lysenko at Ioffe Institute <alexandra.lysenko@mail.ioffe.ru> A. Lysenko, D. Frederiks, A. Ridnaia, D. Svinkin, A. Tsvetkova, M. Ulanov, and T. Cline on behalf of the Konus-Wind team, report: The short-duration GRB 240123C (IPN triangulation: Ridnaia et al., GCN circ. 35627; AstroSat CZTI detection: Joshi et al., GCN circ. 35635; GRBAlpha detection: Dafcikova et al., GCN circ. 35643) triggered Konus-Wind at T0=83553.043 s UT (23:12:33.043). The burst light curve shows a single-pulse structure which starts at ~T0-0.1 s and has a total duration of ~1.0 s. The emission is seen up to 1 MeV. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB240123_T83553/ As observed by Konus-Wind, the burst had a fluence of 2.91(-0.22,+0.23)x10^-6 erg/cm2, and a 16-ms peak flux, measured from T0+0.160s, of 1.17(-0.32,+0.33)x10^-5 erg/cm2/s (both in the 20 keV - 10 MeV energy range). A time-averaged spectrum of the burst (measured from T0 to T0+0.256 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 = 0.85(-0.40,+0.46) and Ep = 210(-17,+19) keV (chi2 = 24/38 dof). Fitting by a GRB (Band) model yields the close alpha and Ep, and an upper limit on the high energy photon index: beta < -2.8 (chi2 = 22/37 dof). All the quoted errors are at the 90% confidence level. All the quoted values are preliminary. View this GCN Circular online at https://gcn.nasa.gov/circulars/35658. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...