{
  "bibcode": "2024GCN.35835....1F",
  "eventId": "GRB 240225B",
  "submittedHow": "email-legacy",
  "createdOn": 1709217996694,
  "circularId": 35835,
  "subject": "Konus-Wind detection of GRB 240225B (long)",
  "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\nGRB 240225B (MAXI/GCS detection: Nakajima et al., GCN 35796;\nAstroSat CZTI detection: Joshi al., GCN 35798)\ntriggered Konus-Wind (KW) at T0=72727.251 s UT (20:12:07.251),\ni.e., ~3.5 min before the MAXI trigger.\n\nThe burst light curve shows a multi-peaked emission\npulse, which starts at ~T0 - 2 s, peaks around ~T0 + 6 s,\nand has a total duration of ~35 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/GRB240225_T72727/\n\nAs observed by Konus-Wind, the burst had\na fluence of (2.16 ± 0.35)x10^-5 erg/cm^2 and\na 64-ms peak energy flux, measured from T0 + 6.144 s,\nof (2.87 ± 0.41)x10^-6 erg/cm^2/s (both in the 20 keV - 10 MeV energy range).\n\nA time-averaged spectrum (measured from T0 to T0+41.216 s)\nis best fit in the 20 keV - 15 MeV range\nby a GRB (Band) function with the following model parameters:\nthe low-energy photon index alpha = -1.37 (-0.14,+0.15),\nthe high energy photon index beta = -2.74 (-7.26,+0.43),\nthe peak energy Ep = 270 (-43,+64) keV,\nchi2 = 107/97 dof.\n\nA spectrum near the peak count rate (measured from T0 to T0+8.448 s)\nis best fit in the 20 keV - 15 MeV range\nby a GRB (Band) function with the following model parameters:\nthe low-energy photon index alpha = -0.85 (-0.110,+0.10),\nthe high energy photon index beta = -2.43 (-0.55,+0.24),\nthe peak energy Ep = 287 (-47,+59) keV,\nchi2 = 75/79 dof.\n\nAssuming the redshift z=0.946 (Schneider et al., GCN 35832)\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 (5.38 ± 0.95)x10^52 erg,\nthe isotropic peak luminosity L_iso to (1.87 ± 0.27)x10^52 erg/s,\nthe rest-frame peak energy of the time-integrated spectrum Ep,i,z to ~525 keV,\nand the rest-frame peak energy at the peak of the emission Ep,p,z to ~558 keV.\nWith the obtained estimates, GRB 240225B is inside 68% prediction bands for\nboth 'Amati' and '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/GRB240225_T72727/GRB240225B_rest_frame.pdf\n\nAll the quoted errors are estimated at the 68% confidence level.\nAll the presented results are preliminary.\n\n",
  "submitter": "Dmitry Frederiks at Ioffe Institute <fred@mail.ioffe.ru>"
}