{
  "bibcode": "2013GCN.15145....1G",
  "body": "S. Golenetskii, R.Aptekar, D. Frederiks, V. Pal'shin,\nP. Oleynik, M. Ulanov, D. Svinkin, and T. Cline on behalf\nof the Konus-Wind team, report:\n\nThe long-duration soft-spectrum GRB 130831A\n(Swift-BAT trigger 568849: Hagen, et al., GCN 15139)\ntriggered Konus-Wind at T0=47062.044 s UT (13:04:22.044)\n\nThe light curve shows a smooth pulse peaked at ~T0+1.6 s\nfollowed by a weaker emission till ~T0+35~s.\nThe emission is seen up to ~6 MeV.\n\nThe Konus-Wind light curve of this GRB is available at\nhttp://www.ioffe.ru/LEA/GRBs/GRB130831_T47062/\n\nAs observed by Konus-Wind, the burst\nhad a fluence of (7.6 �� 0.4)x10-6 erg/cm2,\nand a 64-ms peak flux, measured from T0+1.600 s,\nof (2.5 �� 0.3)x10-6 erg/cm2/s\n(both in the 20 keV - 10 MeV energy range).\n\nThe time-averaged spectrum (measured from T0 to T0+24.832 s)\nis best fit in the 20 keV - 15 MeV range\nby the GRB (Band) function with the following model parameters:\nthe low-energy photon index alpha = -1.61 �� 0.06,\nthe high energy photon index beta = -3.3 �� 0.3,\nthe peak energy Ep = 55 �� 4 keV,\nchi2 = 118/97 dof.\n\nThe spectrum at the maximum count rate (measured from T0 to T0+8.448 s)\nis best fit in the 20 keV - 15 MeV range\nby the GRB (Band) function with the following model parameters:\nthe low-energy photon index alpha = -1.51 �� 0.10,\nthe high energy photon index beta = -2.8 �� 0.1,\nthe peak energy Ep = 67 �� 4 keV,\nchi2 = 91/96 dof.\n\nAssuming Gemini-North redshift z=0.4791 (Cucchiara & Perley, GCN 15144),\nand a standard cosmology model with H_0 = 70 km/s/Mpc,\nOmega_M = 0.27, and Omega_Lambda = 0.73,\nwe estimate the following rest-frame parameters of GRB 130831A:\nthe isotropic energy release E_iso is (4.6 �� 0.2)x10^51 erg,\nthe peak luminosity (L_iso)_max is (2.7 �� 0.3)x10^51 erg/s,\nand the rest-frame peak energy Ep,i = (81 �� 6) keV\n\nAll the quoted results are preliminary.",
  "circularId": 15145,
  "createdOn": 1377975031000,
  "email": "fred@mail.ioffe.ru",
  "subject": "Konus-Wind observation of GRB 130831A",
  "submitter": "Dmitry Frederiks at Ioffe Institute  <fred@mail.ioffe.ru>",
  "eventId": "GRB 130831A"
}