{
  "bibcode": "2025GCN.42683....1S",
  "eventId": "GRB 251103A",
  "circularId": 42683,
  "submittedHow": "web",
  "format": "text/plain",
  "subject": "Konus-Wind detection of GRB 251103A",
  "createdOn": 1763138700423,
  "submitter": "Dmitry Svinkin at Ioffe Institute <svinkin@mail.ioffe.ru>",
  "body": "D. Svinkin, D. Frederiks, A. Lysenko, A. Ridnaia,\nA. Tsvetkova, M. Ulanov, and T. Cline\non behalf of the Konus-Wind team, report: \n\nThe long-duration GRB 251103A\n(SVOM-ECLAIRs detection: Hu et al., GCN 42534;\nFermi-GBM detection: The Fermi GBM team, GCN 42536;\nSonawane and Godwin, GCN 42553;\nSVOM-GRM detection: Wang et al., GCN 42552;\nInsight-HXMT/HE detection: Ren et al., GCN 42572)\ntriggered Konus-Wind at T0=17189.335 s UT (04:46:29.335).\n\nThe burst light curve shows a single pulse\nwhich starts at ~T0-0.5 s and has a total duration of ~5.5 s.\nThe emission is seen up to ~2 MeV.\n\nThe Konus-Wind light curve of this GRB is available at\nhttp://www.ioffe.ru/LEA/GRBs/GRB251103_T17189/\n\nAs observed by Konus-Wind, the burst\nhad the total fluence of 9.48(-0.93,+1.02)x10^-6 erg/cm2,\nand the 64-ms peak flux, measured from T0+0.022 s,\nof 6.52(-2.04,+2.79)x10^-6 erg/cm2/s\n(both in the 20 keV - 10 MeV energy range).\n\nThe time-averaged spectrum of the burst\n(measured from T0 to T0+8.448 s)\nis best fit in the 20 keV - 15 MeV range\nby the GRB (Band) model with the following parameters:\nthe low-energy photon index alpha = -0.33(-0.71,+1.08),\nthe high energy photon index beta = -2.21(-0.11,+0.09),\nthe peak energy Ep = 86(-15,+25) keV\n(chi2 = 86/80 dof).\n\nThe spectrum near the maximum count rate\n(measured from T0 to T0+0.256 s)\nis best fit in the 20 keV - 2 MeV range\nby the GRB (Band) model with the following parameters:\nthe low-energy photon index alpha = -0.97(-0.42,+0.99),\nthe high energy photon index beta = -2.25(-7.75,+0.39),\nthe peak energy Ep = 292(-160,+184) keV\n(chi2 = 16/18 dof).\n\nAssuming the redshift z=0.76 (Izzo et al., GCN 42540)\nand a standard cosmology with H_0 = 67.3 km/s/Mpc, Omega_M = 0.315,\nand Omega_Lambda = 0.685 (Planck Collaboration, 2014),\nwe estimate the following rest-frame parameters:\nthe isotropic energy release E_iso is 1.53(-0.15,+0.16)x10^52 erg,\nthe peak luminosity L_iso is 1.85(-0.58,+0.79)x10^52 erg/s,\nthe rest-frame peak energy of the time-averaged spectrum\nEp,i,z is 151(-27,+44) keV and the spectrum near the maximum count rate\nEp,p,z is 513(-281,+324) keV.\n\nWith the obtained estimates, GRB 251103A is inside 68% prediction bands \nfor both the 'Amati' and the 'Yonetoku' relations derived for the sample \nof >300 long KW GRBs with known redshifts (Tsvetkova et al., 2017; Tsvetkova et al., 2021),\nsee http://www.ioffe.ru/LEA/GRBs/GRB251103_T17189/GRB251103A_rest_frame.pdf\n\nAll the quoted errors are at the 68% confidence level.\nAll the quoted values are preliminary."
}