KonusWind detection of GRB 210204A (correction to GCN 29415)
Abstract
The KW spectral data and energetics of GRB 210204A reported in Frederiks et al., GCN 29415 contain errors due to an incorrect detector response matrix used in the calculations. The correct spectra and energetics are provided below, we are sorry for the inconvenience. The burst timeintegrated spectrum (measured from T0 to T0+49.408 s) is best fit in the 20 keV  20 MeV range by the GRB (Band) function with the following model parameters: the lowenergy photon index alpha = 1.45 (0.08,+0.09), the high energy photon index beta = 2.63 (0.41,+0.20), the peak energy Ep = 136 (16,+21) keV, chi2 = 76/97 dof. The spectrum near the peak count rate (measured from T0 to T0+8.448 s) is best fit in the 20 keV  20 MeV range by the GRB (Band) function with the following model parameters: the lowenergy photon index alpha = 1.12 (0.18,+0.34), the high energy photon index beta = 2.45 (0.46,+0.26), the peak energy Ep = 175 (42,+34) keV, chi2 = 104/96 dof. As observed by KonusWind, the burst had a fluence of (7.0 ± 0.9)x10^5 erg/cm^2 and a 64ms peak energy flux, measured from T0+2.304, of (5.2 ± 0.9)x10^6 erg/cm^2/s (both in the 20 keV  10 MeV energy range). Assuming the redshift z=1.466 (Izzo et al., GCN 29411) and a standard cosmology with H_0 = 67.3 km/s/Mpc, Omega_M = 0.315, and Omega_Lambda = 0.685 (Planck Collaboration, 2014), we estimate the isotropic energy release E_iso to ~3.9x10^53 erg, the isotropic luminosity L_iso to ~7.1x10^52 erg/s, and the restframe peak energy of the timeintegrated spectrum Ep,z to ~333 keV. With these values, GRB 210204A is within 68% prediction bands for both 'Amati' and 'Yonetoku' relations for the sample of >300 long KW GRBs with known redshifts (Tsvetkova et al., ApJ, in press), see http://www.ioffe.ru/LEA/GRBs/GRB210204_T23570/GRB210204A_rest_frame.pdf All the quoted errors are estimated at the 90% confidence level. All the presented results are preliminary.
 Publication:

GRB Coordinates Network
 Pub Date:
 February 2021
 Bibcode:
 2021GCN.29424....1F