{
  "bibcode": "2020GCN.29150....1F",
  "body": "D. Frederiks, S. Golenetskii, R.Aptekar, A. Kozlova, A.Lysenko,\nD. Svinkin, A. Tsvetkova,  M. Ulanov, T. Cline, on behalf of the Konus-Wind team,\nand A. Lien (GSFC/UMBC), report:\n\nThe long GRB 201221A (Swift-BAT trigger #1013852, T0 = T0(BAT)= 07:09:01.4258 UT:\nPage et al., GCN 29096; Breadmore et al., GCN 29108;\nFermi GBM Sub-Threshold Detection: Veres, GCN 29110, 29111)\nwas detected by Konus-Wind (KW) in the waiting mode.\n\nA Bayesian block analysis of the KW waiting mode data in the 20-400 keV band\nreveals a ~11 sigma count rate increase over background in the interval\nfrom ~T0(BAT)-10 s to ~T0(BAT)+20 s.\nThe KW light curve of this burst is available\nat http://www.ioffe.ru/LEA/GRBs/GRB201221A/\n\nTo derive the broad-band spectral parameters of this burst, we performed\na joint spectral analysis of the Swift/BAT data (15-150 keV) and the Konus-Wind\n3-channel spectral data, which cover the energy range from ~20 keV to ~1.5 MeV.\n\nThe time-averaged spectrum, measured from T0(BAT)-9.6 s to T0(BAT)+19.8 s,\nis best fit in the 15 keV - 1.5 MeV range by the GRB (Band)\nfunction with the following model parameters:\nthe low-energy photon index alpha = -0.95 (-0.22,+0.31),\nthe high energy photon index beta = -2.39 (-0.89,+0.38),\nand the peak energy Ep = 194 (-63,+81) keV, chi2 = 65/58 dof.\n\nIn the 15-1500 keV band, the total burst fluence S is 4.3(-0.4, + 0.7)x10^-6 erg/cm^2,\nand the 2.944 s peak energy flux Fp is 2.0 (-0.2, + 0.3)x10^-7 erg/cm^2.\nIn the 10-10000 keV band, standard for the KW analysis, S = 5.3(-1.0, + 2.3)x10^-6 erg/cm^2\nand Fp = 2.4 (-0.4, + 1.0)x10^-7 erg/cm^2.\n\nAssuming the redshift z=5.70 (Malesani et al., GCN 29100)\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 isotropic energy release E_iso to 3.0(-0.5,+1.3)x10^53 erg,\nthe isotropic luminosity L_iso to 9.0(-1.6,+3.9)x10^52 erg/s,\nand the rest-frame peak energy of the time-integrated spectrum Ep,z to 1300(-420,+540) keV.\nWith these values, GRB 201221A is within 90% prediction bands\nfor both 'Amati' and 'Yonetoku' relations for the sample of >300 long KW GRBs\nwith known redshifts (part I: Tsvetkova et al., ApJ 850 161, 2017;\npart II: Tsvetkova et al., ApJ, accepted),\nsee http://www.ioffe.ru/LEA/GRBs/GRB201221A/GRB201221A_rest_frame.pdf\n\nAll the quoted errors are estimated at the 68% confidence level.\nAll the presented results are preliminary.",
  "circularId": 29150,
  "createdOn": 1608738703000,
  "email": "fred@mail.ioffe.ru",
  "subject": "GRB 201221A: Konus-Wind detection and joint Konus-Wind + Swift-BAT spectral analysis",
  "submitter": "Dmitry Frederiks at Ioffe Institute  <fred@mail.ioffe.ru>",
  "eventId": "GRB 201221A"
}