{
  "submitter": "Dmitry Svinkin at Ioffe Institute <svinkin@mail.ioffe.ru>",
  "eventId": "GRB 240218A",
  "createdOn": 1708396433595,
  "circularId": 35758,
  "bibcode": "2024GCN.35758....1S",
  "submittedHow": "email-legacy",
  "subject": "Konus-Wind detection of GRB 240218A",
  "body": "D. Svinkin, D. Frederiks, A.Lysenko, A. Ridnaia,\nA. Tsvetkova,  M. Ulanov, and T. Cline,\non behalf of the Konus-Wind team, report:\n\nThe long-duration GRB 240218A\n(Swift-BAT detection: Page et al., GCN 35742;\nFermi-GBM detection: Veres and Meegan, GCN 35755)\nwas detected by Konus-Wind (KW) in the waiting mode.\n\nA Bayesian block analysis of the KW waiting mode data\nin the 20-400 keV band reveals a >10 sigma count rate increase\nin the interval from T0-12.646 s to T0+25.626 s,\nwhere T0 = T0(BAT) = 02:00:00 UT.\nThe burst light curve shows a multi-peaked structure\nwith the brightest peak around ~T0(BAT)+20 s.\n\nThe Konus-Wind light curve of this GRB is available at\nhttp://www.ioffe.ru/LEA/GRBs/GRB240218_T07200/\n\nAs observed by Konus-Wind, the burst had\na total fluence of 7.62(-2.22,+1.72)x10^-6 erg/cm^2 and\na 2.944-s peak energy flux, measured from T0+19.738 s,\nof 5.29(-1.49,+2.21)x10^-7 erg/cm^2/s\n(both in the 20 keV - 10 MeV energy range).\n\nModelling the 3-channel time-integrated spectrum of the burst\n(measured from T0-12.646 s to T0+25.626 s)\nby a power law with exponential cutoff (CPL) model\ndN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)\nyields alpha > -0.56 and Ep = 180(-74,+77) keV.\n\nModelling the 3-channel spectrum near the peak count rate\n(measured from T0+19.738 to T0+25.626 s) by the CPL model\nyields alpha = -1.33(-0.29,+0.53) and Ep = 293(-120,+207) keV.\n\nAssuming the redshift z=6.782 (Saccardi et al., GCN 35756)\nand a standard cosmology with H_0 = 67.3 km/s/Mpc, Omega_M = 0.315,\nand Omega_Lambda = 0.685 (Planck Collaboration, 2014),we estimate\nthe burst isotropic energy release E_iso to 5.4(-1.6,+1.2)x10^53 erg,\nthe isotropic peak luminosity L_iso to 2.9(-0.8,+1.2)x10^53 erg/s,\nthe rest-frame peak energy of the time-integrated spectrum\nEp,i,z to 1401(-576,+599) keV, and the rest-frame peak energy at\nthe peak of the emission Ep,p,z to 2280(-934,+1611) keV.\n\nWith the obtained estimates, GRB 240218A is inside 68% prediction band\nfor both 'Amati' and 'Yonetoku' relations derived for the sample of\n>300 long KW GRBs with known redshifts (Tsvetkova et al., 2017;\nTsvetkova et al., 2021), see http://www.ioffe.ru/LEA/GRBs/GRB240218_T07200/GRB240218A_rest_frame.pdf\n\nAll the quoted errors are estimated at the 68% confidence level.\nAll the presented results are preliminary.\n\n"
}