TITLE: GCN CIRCULAR NUMBER: 37077 SUBJECT: Konus-Wind detection of GRB 240805A DATE: 24/08/06 15:53:16 GMT FROM: Anna Ridnaia at Ioffe Institute ridnaia@mail.ioffe.ru
A. Ridnaia, D. Frederiks, A. Lysenko, D. Svinkin, A. Tsvetkova, M. Ulanov, and T. Cline, on behalf of the Konus-Wind team, report:
The long-duration GRB 240805A (Fermi-GBM observation: The Fermi GBM team, GCN 27031; Godwin et al., GCN 37075; Swift-BAT detection: Dichiara et al., GCN 37032; INTEGRAL IBIS/ISGRI detection: Mereghetti et al., GCN 37037; Götz et al., GCN 37041; Fermi-LAT detection: Gupta et al., GCN 37042; SVOM/GRM observation: Wang et al., GCN 37054) triggered Konus-Wind at T0=7342.029 s UT (02:02:22.029).
The burst light curve shows a multipeaked structure which starts at ~T0-2.3 s and has a total duration of ~15.6 s. The emission is seen up to ~4 MeV.
The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB240805_T07342/
As observed by Konus-Wind, the burst had a fluence of 3.43(-0.31,+0.35)x10^-5 erg/cm2, and a 64-ms peak flux, measured from T0+3.680 s, of 6.61(-1.44,+1.48)x10^-6 erg/cm2/s (both in the 20 keV - 10 MeV energy range).
The time-averaged spectrum of the burst (measured from T0 to T0+15.360 s) is best fit in the 20 keV - 10 MeV range by the GRB (Band) model with the following parameters: the low-energy photon index alpha = -0.46(-0.11,+0.13), the high energy photon index beta = -2.76(-0.43,+0.26), the peak energy Ep = 272(-22,+22) keV (chi2 = 81/80 dof).
The spectrum near the maximum count rate (measured from T0+0.256 to T0+7.168 s) is best fit in the 20 keV - 10 MeV range by the GRB (Band) model with the following parameters: the low-energy photon index alpha = -0.51(-0.12,+0.14), the high energy photon index beta = -2.78(-0.61,+0.29), the peak energy Ep = 279(-26,+27) keV (chi2 = 70/71 dof).
All the quoted errors are at the 90% confidence level. All the quoted values are preliminary.
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