TITLE: GCN CIRCULAR NUMBER: 42683 SUBJECT: Konus-Wind detection of GRB 251103A DATE: 25/11/14 16:45:00 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 251103A (SVOM-ECLAIRs detection: Hu et al., GCN 42534; Fermi-GBM detection: The Fermi GBM team, GCN 42536; Sonawane and Godwin, GCN 42553; SVOM-GRM detection: Wang et al., GCN 42552; Insight-HXMT/HE detection: Ren et al., GCN 42572) triggered Konus-Wind at T0=17189.335 s UT (04:46:29.335). The burst light curve shows a single pulse which starts at ~T0-0.5 s and has a total duration of ~5.5 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/GRB251103_T17189/ As observed by Konus-Wind, the burst had the total fluence of 9.48(-0.93,+1.02)x10^-6 erg/cm2, and the 64-ms peak flux, measured from T0+0.022 s, of 6.52(-2.04,+2.79)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+8.448 s) is best fit in the 20 keV - 15 MeV range by the GRB (Band) model with the following parameters: the low-energy photon index alpha = -0.33(-0.71,+1.08), the high energy photon index beta = -2.21(-0.11,+0.09), the peak energy Ep = 86(-15,+25) keV (chi2 = 86/80 dof). The spectrum near the maximum count rate (measured from T0 to T0+0.256 s) is best fit in the 20 keV - 2 MeV range by the GRB (Band) model with the following parameters: the low-energy photon index alpha = -0.97(-0.42,+0.99), the high energy photon index beta = -2.25(-7.75,+0.39), the peak energy Ep = 292(-160,+184) keV (chi2 = 16/18 dof). Assuming the redshift z=0.76 (Izzo et al., GCN 42540) and a standard cosmology with H_0 = 67.3 km/s/Mpc, Omega_M = 0.315, and Omega_Lambda = 0.685 (Planck Collaboration, 2014), we estimate the following rest-frame parameters: the isotropic energy release E_iso is 1.53(-0.15,+0.16)x10^52 erg, the peak luminosity L_iso is 1.85(-0.58,+0.79)x10^52 erg/s, the rest-frame peak energy of the time-averaged spectrum Ep,i,z is 151(-27,+44) keV and the spectrum near the maximum count rate Ep,p,z is 513(-281,+324) keV. With the obtained estimates, GRB 251103A is inside 68% prediction bands for both the 'Amati' and the 'Yonetoku' relations derived for the sample of >300 long KW GRBs with known redshifts (Tsvetkova et al., 2017; Tsvetkova et al., 2021), see http://www.ioffe.ru/LEA/GRBs/GRB251103_T17189/GRB251103A_rest_frame.pdf 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/42683. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...