TITLE: GCN CIRCULAR NUMBER: 17731 SUBJECT: GRB 150413A: Konus-Wind and Swift/BAT joint spectral analysis DATE: 15/04/23 10:46:32 GMT FROM: Anastasia Tsvetkova at Ioffe Institute S. Golenetskii, R.Aptekar, D. Frederiks, V. Pal'shin, P. Oleynik, M. Ulanov, D. Svinkin, A. Tsvetkova, A.Lysenko, and T. Cline on behalf of the Konus-Wind team, and T. Sakamoto (AGU), S. D. Barthelmy (GSFC), W. Baumgartner (GSFC/UMBC), J. Cummings (GSFC/UMBC), E. Fenimore (LANL), N. Gehrels (GSFC), H. Krimm (GSFC/USRA), C. Markwardt (GSFC), D. Palmer (LANL), M. Stamatikos (OSU) and T. Ukwatta (GWU), report: We performed the Konus-Wind and the Swift/BAT joint spectral analysis of GRB 150413A (Swift/BAT trigger #637899: Markwardt et al., GCN Circ. 17688; Stamatikos et al., GCN Circ. 17701). Since the Konus-Wind observed this GRB in the waiting mode, we only have 3 channel spectral data for the Konus-Wind which cover the energy range from 20 keV to 1.2 MeV. The joint spectral analysis of the Konus-Wind and the Swift/BAT data allows us to derive the broad-band spectral parameters of this burst. The time intervals of the spectral data for each instrument are chosen from T0(BAT)-102.150 s to T0(BAT)+159.866 s (the time-integrated spectrum) and from T0(BAT)+95.098 s to T0(BAT)+118.650 s (the spectrum of the most prominent pulse) where T0(BAT) is the trigger time of BAT at 13:54:58 UTC. The energy ranges which we used in the joint spectral analysis are 20-1200 keV and 15-150 keV for the Konus-Wind and the Swift/BAT respectively. The spectral data of two instruments are fitted with the spectral model multiplied by the constant factor to take into account the systematic effective area uncertainties in the response matrices of each instrument. The spectrum of the most prominent pulse is well fitted with a power-law with exponential cutoff model: dN/dE ~ E^{alpha}*exp(-(2+alpha)*E/Epeak). No systematic residual from the best fit model is seen in the spectral data of each instrument. The BAT constant factor is 0.71(-0.12,+0.16) (the KW constant factor is fixed to 1). The best fit spectral parameters are: alpha = -1.01(-0.44,+0.65), and Epeak = 96(-22,+56) keV (chi2/dof = 60/57). The best fit spectral parameters for the GRB (Band) model fixing beta = -2.5 are: alpha = -1.00(-0.51,+0.84), and Epeak = 91(-26,+77) keV (chi2/dof = 63/57). The time-integrated spectrum is well fitted with a power-law model with the the photon index 1.77(-0.09,+0.09), chi2/dof = 68/58. The BAT constant factor is 0.70(-0.09,+0.11) (the KW constant factor is fixed to 1). The energy fluence in the 15-1200 keV band calculated by a power-law model for this 262.016 s interval is 1.42(-0.19,+0.20)x10^-5 erg/cm2. Assuming a redshift of 3.139 (de Ugarte Postigo and Tomasella, GCN Circ. 17710) and a standard cosmology model with H_0 = 67.3 km/s/Mpc, Omega_M = 0.315, Omega_Lambda = 0.685, the isotropic energy release in the 1 keV - 10 MeV energy range is E_iso = 6.53(-1.29,+1.62)x10^53 erg. All the quoted errors are at the 90% confidence level. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB150413A/