TITLE: GCN CIRCULAR NUMBER: 43517 SUBJECT: Konus-Wind detection of GRB 260120B DATE: 26/01/26 13:06:35 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 260120B (Fermi GBM detection: Fermi GBM team, GCN 43477; Godwin & Meegan, GCN 43489; Swift-BAT detection: Ferro et al., GCN 43479; Palmer et al., GCN 43493; AstroSat CZTI detection: Goyal et al., GCN 43504) triggered Konus-Wind at T0=64826.649 s UT (18:00:26.649). The burst light curve shows a single pulse, which starts at ~T0-3.2 s and has a total duration of ~5.9 s. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB260120_T64826/ As observed by Konus-Wind, the burst had a fluence of 3.41(-0.52,+0.58)x10^-6 erg/cm2, and a 64-ms peak flux, measured from T0-0.064 s, of 1.97(-0.58,+0.60)x10^-6 erg/cm2/s (both in the 20 keV - 10 MeV energy range). Since a major part of the burst emission was detected before the trigger, the spectral analysis was performed using the KW 3-channel light curve data. Modelling the KW 3-channel time-integrated spectrum (measured from T0-3.173 s to T0+2.720 s) by a power law with exponential cutoff (CPL) model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep), yields alpha = -0.56(-0.23,+0.30) and Ep = 246(-53,+67) keV. All the quoted errors are at the 68% confidence level. All the quoted values are preliminary. View this GCN Circular online at https://gcn.nasa.gov/circulars/43517. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...