{
  "bibcode": "2019GCN.25974....1S",
  "body": "D. Svinkin, S. Golenetskii, R. Aptekar, D. Frederiks,\nM. Ulanov, A. Tsvetkova, A. Lysenko, A. Kozlova, and T. Cline\non behalf of the Konus-Wind team, report:\n\nThe long-duration GRB 191004B\n(Swift-BAT detection: Cenko et al., GCN circ. 25947;\nStamatikos et al., GCN circ. 25955)\ntriggered Konus-Wind at T0=77626.99 s UT (21:33:46.990).\n\nThe burst light curve shows a multi-peaked structure\nwhich starts at ~T0-0.5 s and has a total duration of ~5.5 s.\nThe emission is seen up to ~1 MeV.\n\nThe Konus-Wind light curve of this GRB is available at\nhttp://www.ioffe.ru/LEA/GRBs/GRB191004_T77626/\n\nAs observed by Konus-Wind, the burst\nhad a fluence of 4.13(-0.40,+0.45)x10^-6 erg/cm2,\nand a 64-ms peak flux, measured from T0+3.504 s,\nof 2.56(-0.73,+0.74)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 - 10 MeV range\nby a power law with exponential cutoff model:\ndN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)\nwith  alpha = -0.51(-0.30,+0.34)\nand Ep = 172(-21,+27) keV (chi2 = 59/57 dof).\nFitting by a GRB (Band) model yields the same alpha and Ep,\nand an upper limit on the high energy photon index: beta < -3.0\n(chi2 = 59/56 dof).\n\nAssuming the redshift z=1.260 (D'Elia et al., GCN circ. 25956)\nand a standard cosmology model with H_0 = 67.3 km/s/Mpc,\nOmega_M = 0.315, and Omega_Lambda = 0.685 (Planck Collaboration, 2014),\nwe estimate the following rest-frame parameters:\nthe isotropic energy release E_iso is 1.79(-0.17,+0.20)x10^52 erg,\nthe peak luminosity L_iso is 2.51(-0.72,+0.73)x10^52 erg/s,\nand the rest-frame peak energy of the time-integrated spectrum,\nEp,i, is 389(-47,+61) keV.\nWith these energetics, the burst lies within the 90% prediction bands\nfor both 'Amati' and 'Yonetoku' relations built for the sample\nof 138 long KW GRBs with known redshifts\n(Tsvetkova et al., ApJ 850 161, 2017).\n\nAll the quoted errors are at the 90% confidence level.\nAll the quoted values are preliminary.",
  "circularId": 25974,
  "createdOn": 1570471256000,
  "email": "svinkin@mail.ioffe.ru",
  "subject": "Konus-Wind observation of GRB 191004B",
  "submitter": "Dmitry Svinkin at Ioffe Institute  <svinkin@mail.ioffe.ru>",
  "eventId": "GRB 191004B"
}