TITLE: GCN CIRCULAR NUMBER: 24452 SUBJECT: Konus-Wind observation of GRB 190501A DATE: 19/05/10 12:50:16 GMT FROM: Anastasia Tsvetkova at Ioffe Institute A. Tsvetkova, S. Golenetskii, R.Aptekar, D. Frederiks, M. Ulanov, D. Svinkin, A. Lysenko, A. Kozlova and T. Cline on behalf of the Konus-Wind team, report: The long-duration, bright GRB 190501A (AGILE/MCAL and scientific ratemeters detection: Ursi  et al., GCN 24360; AGILE/GRID detection: Lucarelli et al., GCN 24361; Verrecchia et al., GCN 24363; IPN Triangulation: Hurley et al., GCN 24372; CALET Gamma-Ray Burst Monitor detection: Ricciarini t al., GCN 24406) triggered Konus-Wind at T0=19401.146 s UT (05:23:21.146). The burst light curve shows a bright, multi-peaked pulse with a duration of ~50 s followed by a weak tail up to 137 s. The emission is seen up  to ~1200 keV,  no KW data above 1.2 MeV are available at the time of writing. As observed by Konus-Wind, the burst had a fluence of 2.04(-0.13,+0.13)x10^-4 erg/cm2, and a 64-ms peak energy flux, measured from T0+4.272 s, of 3.55(-0.99,+0.99)x10^-5 erg/cm2/s (both in the 20 keV - 10 MeV energy range). The time-integrated spectrum of the burst (measured from T0 to T0+22.784 s) is best fit in the 20 keV - 1.2 MeV range by the GRB (Band) model with the following parameters: the low-energy photon index alpha = -0.91(-0.04,+0.04), the high energy photon index beta = -2.10(-0.09,+0.08), the peak energy Ep = 316(-23,+24) keV, chi2 = 70/59 dof. The spectrum near the peak count rate (measured from T0+3.840 to T0+4.352 s) is best fit in the 20 keV - 1.2 MeV range by the GRB (Band) model with the following parameters: the low-energy photon index alpha = -0.65(-0.11,+0.14), the high energy photon index beta = -2.28(-1.52,+0.31), the peak energy Ep = 410(-72,+77) keV, chi2 = 53/47 dof. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB190501_T19401/ All the quoted errors are at the 90% confidence level. All the quoted values are preliminary.