TITLE: GCN CIRCULAR NUMBER: 38526 SUBJECT: Konus-Wind detection of GRB 241209D DATE: 24/12/10 14:55:58 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 241209D (Fermi-GBM detection: Fermi GBM team, GCN 38488; Malacaria & Meegan, GCN 38507; Swift-BAT detection: Parsotan et al., GCN 38489; AstroSat CZTI detection: Tembhurnikar et al., GCN 38518) was detected by Konus-Wind (KW) in the waiting mode. A Bayesian block analysis of the KW waiting mode data in the 20-300 keV band reveals a >13 sigma count rate increase in the interval from T0-2.0 s to T0+42.160 s where T0 = T0(BAT) = 10:59:45.649 UT. The KW light curve of this burst is available at http://www.ioffe.ru/LEA/GRBs/GRB241209D/ Modeling a time-integrated spectrum of the burst (from T0-2.0 s to T0+42.160 s) by a power law with exponential cutoff (CPL) model dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep): yields alpha = -1.16 (-0.37, +4.03) and Ep = 90(-12,+14) keV. The total burst fluence is 8.79(-0.87,+1.74)x10^-6 erg/cm^2, and the 2.944 s peak energy flux, measured from T0-2.0 s, is 5.86(-0.75,+1.25)x10^-7 erg/cm^2. (both in the 20 keV - 10 MeV energy range). All the quoted errors are estimated at the 68% confidence level. All the presented results are preliminary. View this GCN Circular online at https://gcn.nasa.gov/circulars/38526. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...