{
  "bibcode": "2021GCN.30196....1F",
  "body": "D. Frederiks, S. Golenetskii, A.Lysenko, A. Ridnaia,\nD. Svinkin, A. Tsvetkova,  M. Ulanov, and T. Cline,\non behalf of the Konus-Wind team, report:\n\nThe long GRB 210610B (Swift detection: Page et al., GCN 30170;\nAGILE detection: Ursi et al., GCN 30195)\ntriggered Konus-Wind (KW) at T0=71488.184 s UT (19:51:28.184).\n\nThe burst light curve shows a bright, multi-peaked emission pulse\nwhich starts at ~T0-27 s, and has a total duration of ~100 s.\nThe emission is seen up to ~10 MeV.\n\nThe Konus-Wind light curve of this GRB is available at\nhttp://www.ioffe.ru/LEA/GRBs/GRB210610_T71488/\n\nAs observed by Konus-Wind, the burst had\na fluence of (1.3 �� 0.1)x10^-4 erg/cm^2 and\na 64-ms peak energy flux, measured from T0 + 10.175 s,\nof (1.0 �� 0.1)x10^-5 erg/cm^2/s (both in the 20 keV - 10 MeV energy range).\n\nThe time-integrated spectrum (measured from T0 to T0+80.384 s)\nis best fit in the 20 keV - 20 MeV range\nby the GRB (Band) function with the following model parameters:\nthe low-energy photon index alpha = -0.61 (-0.04,+0.04),\nthe high energy photon index beta = -2.77 (-0.37,+0.21),\nthe peak energy Ep = 257 (-14,+15) keV,\nchi2 = 97/97 dof.\n\nThe spectrum near the peak count rate (measured from T0+8.192\nto T0+11.775 s) is 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 = -0.20 (-0.10,+0.12),\nthe high energy photon index beta = -3.04 (-0.64,+0.34),\nthe peak energy Ep = 333 (-24,+23) keV,\nchi2 = 60/76 dof.\n\nAssuming the redshift z=1.1345 (de Ugarte Postigo et al., GCN 30194)\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 isotropic energy release E_iso to ~4.6x10^53 erg,\nthe isotropic luminosity L_iso to ~7.6x10^52 erg/s,\nand the rest-frame peak energy of the time-integrated spectrum Ep,z to ~550 keV.\nWith these values, GRB 210204A is within 68% prediction bands\nfor both 'Amati' and 'Yonetoku' relations for the sample of >300 long KW GRBs\nwith known redshifts (Tsvetkova et al., 2021, ApJ, 908, 83),\nsee http://www.ioffe.ru/LEA/GRBs/GRB210610_T71488/GRB210610B_rest_frame.pdf\n\nAll the quoted errors are estimated at the 90% confidence level.\nAll the presented results are preliminary.",
  "circularId": 30196,
  "createdOn": 1623407582000,
  "email": "fred@mail.ioffe.ru",
  "subject": "Konus-Wind detection of GRB 210610B",
  "submitter": "Dmitry Frederiks at Ioffe Institute  <fred@mail.ioffe.ru>",
  "eventId": "GRB 210610B"
}