{
  "circularId": 40948,
  "createdOn": 1751635326417,
  "submitter": "Dmitry Frederiks at Ioffe Institute <fred@mail.ioffe.ru>",
  "body": "D. Frederiks, A.Lysenko, A. Ridnaia, D. Svinkin,\nA. Tsvetkova,  M. Ulanov, and T. Cline,\non behalf of the Konus-Wind team, report:\n\nThe long-duration GRB 250702F (Fermi-GBM detection:\nThe Fermi GBM team, GCN 40892; Mukherjee & Meegan, GCN 40927;\nSwift detection: Klingler et al., GCN 40894)\ntriggered Konus-Wind (KW) at T0=76042.205 s UT (21:07:22.205).\n\nThe burst shows multiple emission pulses and has a total duration of ~46 s.\nThe emission is seen up to ~3 MeV.\n\nThe Konus-Wind light curve of this GRB is available at\nhttp://www.ioffe.ru/LEA/GRBs/GRB250702_T76042/\n\nAs observed by Konus-Wind, the burst had\na fluence of (1.60 ± 0.25)x10^-5 erg/cm^2 and\na 64-ms peak energy flux, measured from T0 + 0.512 s,\nof (5.02 ± 1.15)x10^-6 erg/cm^2/s (both in the 20 keV - 10 MeV energy range).\n\nModeling the time-integrated spectrum of the burst\nby a power law with exponential cutoff (CPL) model\ndN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)\nyields alpha = -1.47 (-0.10, + 0.10) and Ep = 480(-130,+250) keV.\n\nThe spectrum near the peak count rate (measured from T0 to T0+8.448 s)\nis best fit in the 20 keV - 15 MeV range by a GRB (Band) function\nwith the following model parameters:\nthe low-energy photon index alpha = -1.22 (-0.12,+0.17),\nthe high energy photon index beta = -2.20 (-7.8,+0.29),\nthe peak energy Ep = 505 (-155,+326) keV,\nchi2 = 85/94 dof.\n\nAssuming the redshift z=1.520 (de Ugarte Postigo et al., GCN 40896)\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 burst isotropic energy release E_iso to (9.9 ± 1.5)x10^52 erg,\nthe isotropic peak luminosity L_iso to (7.8 ± 1.8)x10^52 erg/s, and\nthe rest-frame peak spectral energy Ep,z to ~1250 keV.\nWith the obtained estimates, GRB 250702F is consistent with 90% prediction bands\nof both 'Amati' and 'Yonetoku' relations for the sample of >300 long KW GRBs\nwith known redshifts (Tsvetkova et al., 2017; Tsvetkova et al., 2021),\nsee http://www.ioffe.ru/LEA/GRBs/GRB250702_T76042/GRB250702F_rest_frame.pdf\n\nAll the quoted errors are estimated at the 68% confidence level.\nAll the presented results are preliminary.\n",
  "eventId": "GRB 250702F",
  "submittedHow": "email",
  "bibcode": "2025GCN.40948....1F",
  "subject": "Konus-Wind detection of GRB 250702F"
}