TITLE: GCN CIRCULAR NUMBER: 27635 SUBJECT: Konus-Wind observation of GRB 200422A DATE: 20/04/24 13:49:14 GMT FROM: Dmitry Svinkin at Ioffe Institute D. Svinkin, S. Golenetskii, R. Aptekar, D. Frederiks, M. Ulanov, A. Tsvetkova, A. Lysenko, A. Ridnaia, and T. Cline on behalf of the Konus-Wind team, report: The long-duration, very bright GRB 200422A (IPN triangulation: Hurley et al., GCN Circ. 27626; AstroSat-CZTI detection: Gupta et al., GCN Circ. 27630) triggered Konus-Wind at T0=26537.847 s UT (07:22:17.847). The burst light curve shows a multipeaked structure which starts at ~T0-8.3 s and has a total duration of ~40 s. The emission is seen up to ~10 MeV. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB200422_T26537/ As observed by Konus-Wind, the burst had a fluence of 5.12(-0.15,+0.15)x10^-4 erg/cm2, and a 64-ms peak flux, measured from T0+3.728 s, of 1.42(-0.12,+0.12)x10^-4 erg/cm2/s (both in the 20 keV - 10 MeV energy range). The time-averaged spectrum of the burst (measured from T0 to T0+38.656 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 = -0.67(-0.05,+0.05), the high energy photon index beta = -1.94(-0.04,+0.04), the peak energy Ep = 552(-38,+42) keV (chi2 = 105/97 dof). The spectrum near the maximum count rate (measured from T0+3.584 to T0+4.096 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 = -0.63(-0.11,+0.12), the high energy photon index beta = -1.89(-0.09,+0.07), the peak energy Ep = 762(-138,+174) keV (chi2 = 89/79 dof). All the quoted errors are at the 90% confidence level. All the quoted values are preliminary.