TITLE: GCN CIRCULAR NUMBER: 43405 SUBJECT: Konus-Wind detection of GRB 251230A / EP251230a DATE: 26/01/14 19:13:21 GMT FROM: Dmitry Svinkin at Ioffe Institute <svinkin@mail.ioffe.ru> D. Svinkin, D. Frederiks, A. Lysenko, A. Ridnaia, A. Tsvetkova, M. Ulanov, and T. Cline on behalf of the Konus-Wind team, report: The long-duration GRB 251230A / EP251230a (Swift-BAT detection: Lanava et al., GCN 43252; Einstein Probe-WXT detection: Wang et al., GCN 43259; Wang et al., GCN 43272; Insight-HXMT/HE detection: Guo et al., GCN 43299; GECAM-B detection: Guo et al., GCN 43301) triggered Konus-Wind at T0=04927.542 s UT (01:22:07.542). The burst light curve shows a multipeaked structure which starts at ~T0-25 s and has a total duration of ~73 s. The emission is seen up to ~2 MeV. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB251230_T04927/ As observed by Konus-Wind, the burst had the total fluence of 2.03(-0.15,+0.17)x10^-5 erg/cm2, and the 64-ms peak flux, measured from T0-0.224 s, of 2.51(-0.71,+0.80)x10^-6 erg/cm2/s (both in the 20 keV - 10 MeV energy range). The time-averaged spectrum of the burst (measured from T0 to T0+49.408 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 = -1.04(-0.14,+0.16) and Ep = 354(-47,+64) keV (chi2 = 93/98 dof). Fitting by a GRB (Band) model yields the same alpha and Ep, and an upper limit on the high energy photon index: beta < -2.2 (chi2 = 93/97 dof). The spectrum near the maximum count rate (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 = -0.70(-0.51,+0.72) and Ep = 350(-85,+147) keV (chi2 = 19/15 dof). Fitting by a GRB (Band) model yields the same alpha and Ep, and an upper limit on the high energy photon index: beta < -2.8 (chi2 = 18/14 dof). 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/43405. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...