{
  "circularId": 45046,
  "submittedHow": "web",
  "format": "text/plain",
  "eventId": "GRB 260623B",
  "body": "D. Svinkin, D. Frederiks, A.Lysenko, A. Ridnaia, A. Tsvetkova,\nM. Ulanov, and T. Cline, on behalf of the Konus-Wind team, report:\n\nThe long-duration GRB 260623B\nwas detected by Konus-Wind (KW) in the waiting mode \nat about T0 = T0(EP) = 10445 s UT (02:54:05).\nA Bayesian block analysis of the KW waiting mode data in\nthe 20-300 keV band reveals a ~10 sigma count-rate increase in\nthe interval from T0-259 s to T0+327 s.\n\nThe burst overlaps in time with EP260623a (EP-WXT detection: Wang et al., GCN 45020; \nWang et al., GCN 45035) and the KW ecliptic latitude response is consistent with the EP260623a localization.\nThe positional and temporal coincidence of GRB 260623B with\nthe EP260623a supports the conclusion that both events have a common origin.\n\nThe KW light curve of this burst is available\nat http://www.ioffe.ru/LEA/GRBs/GRB260623B\n\nThe total burst fluence is 8.2(-1.2,+1.2)x10^-6 erg/cm^2,\nand the 2.944 s peak energy flux, measured from T0+3.366 s,\nis 0.7(-0.3,+0.4)x10^-7 erg/cm^2/s.\n(both in the 20 keV - 1500 keV energy range).\n\nThe time-integrated spectrum of the burst,\nmeasured from T0-258.650 s to T0+327.206 s,\ncan be described by a power law with exponential cutoff (CPL) model\ndN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)\nwith alpha > -1.16 and Ep = 76(-8,+28) keV.\n\nThe spectrum near the maximum count rate\n(measured from T0-2.522 to T0+38.694 s)\ncan be described with the CPL model with alpha > -1.42 and Ep = 87(-15,+83) keV.\n\nAssuming the redshift z=0.703 (Izzo et al., GCN 45022)\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 1.13(-0.16,+0.24)x10^52 erg,\nthe peak luminosity L_iso is 1.71(-0.72,+0.97)x10^50 erg/s,\nthe rest-frame peak energy of the time-averaged spectrum\nEp,i,z is 130(-14,+47) keV and the spectrum near the maximum count rate\nEp,p,z is 148(-26,+143) keV.\n\nWith the obtained estimates, GRB 260623B is inside the 68% prediction band for\nthe 'Amati' and inside the 90% prediction band for the 'Yonetoku' relations derived for the sample of >300 long\nKW GRBs with known redshifts (Tsvetkova et al., 2017; Tsvetkova et al., 2021),\nsee http://www.ioffe.ru/LEA/GRBs/GRB260623B/GRB260623B_rest_frame.pdf\n\nAll the quoted errors are estimated at the 68% confidence level.\nAll the presented results are preliminary.",
  "subject": "Konus-Wind detection of GRB 260623B / EP260623a",
  "createdOn": 1782486711177,
  "submitter": "Dmitry Svinkin at Ioffe Institute <svinkin@mail.ioffe.ru>"
}