{
  "format": "text/plain",
  "body": "A. Ridnaia, D. Frederiks, A. Lysenko, V. Panteleeva,\nD. Svinkin, A. Tsvetkova,  M. Ulanov, and T. Cline,\non behalf of the Konus-Wind team, report:\n\nThe long-duration GRB 260924A\n(Fermi-GBM detection: Fermi GBM team, GCN 45712;\nMcDermott & Scotton, GCN 45723;\nSwift detection: D'Elia et al., GCN 45713;\nGupta et al., GCN 45733;\nAstroSat-CZTI detection: Salunke et al., GCN 45720;\nFermi-LAT detection: Airasca et al., GCN 45721;\nNustar detection: Waratkar & Grefenstette, GCN 45732;\nSVOM-GRM detection: Yu et al., GCN 45741)\ntriggered Konus-Wind at T0=04406.079 s UT (01:13:26.079).\n\nThe burst light curve shows two separated multipeaked emission episodes.\nThe first episode starts at ~T0-3.5 s and has a total duration of ~212 s,\nthe second starts at ~T0+328 s and lasts up to ~T0+361 s.\nThe emission is seen up to ~8 MeV.\n\nThe Konus-Wind light curve of this GRB is available at\nhttp://www.ioffe.ru/LEA/GRBs/GRB260924_T04406/\n\nAs observed by Konus-Wind, the burst\nhad the total fluence of 3.83(-0.40,+0.43)x10^-4 erg/cm2,\nand the 64-ms peak flux, measured from T0+108.288 s,\nof 1.10(-0.16,+0.16)x10^-5 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+360.704 s)\nis best fit in the 20 keV - 10 MeV range\nby the GRB (Band) model with the following parameters:\nthe low-energy photon index alpha = -0.62(-0.11,+0.14),\nthe high energy photon index beta = -2.37(-0.31,+0.20),\nthe peak energy Ep = 497(-61,+59) keV\n(chi2 = 91/97 dof).\n\nThe spectrum near the maximum count rate\n(measured from T0+106.752 to T0+114.944 s)\nis best fit in the 20 keV - 10 MeV range\nby the GRB (Band) model with the following parameters:\nthe low-energy photon index alpha = -0.62(-0.09,+0.11),\nthe high energy photon index beta = -2.41(-0.23,+0.17),\nthe peak energy Ep = 596(-60,+63) keV\n(chi2 = 82/86 dof).\n\nAssuming the redshift z=3.510 (Castro-Tirado et al., GCN 45740)\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 1.00(-0.11,+0.11)x10^55 erg\n(on a par with the most energetic to date GRB 221009A, Frederiks et al., 2023),\nthe peak luminosity L_iso is 1.30(-0.19,+0.19)x10^54 erg/s (one of the most \nluminous GRBs to date), the rest-frame peak energy of the time-averaged spectrum\nEp,i,z is 2242(-275,+267) keV and the spectrum near the maximum count rate\nEp,p,z is 2690(-270,+285) keV.\n\nWith the obtained estimates, GRB 260924A is inside 68% prediction bands for\nboth the 'Amati' and 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/GRB260924_T04406/GRB260924A_rest_frame.pdf\n\nAll the quoted errors are at the 68% confidence level.\nAll the quoted values are preliminary.",
  "eventId": "GRB 260924A",
  "eventType": [
    "GRB",
    "Gamma-ray Transient"
  ],
  "circularId": 45751,
  "submitter": "Anna Ridnaia at Ioffe Institute <ridnaia@mail.ioffe.ru>",
  "subject": "Konus-Wind detection of GRB 260924A",
  "submittedHow": "web",
  "createdOn": 1790368637549
}