TITLE: GCN CIRCULAR NUMBER: 16265 SUBJECT: Konus-Wind observation of GRB 140512A DATE: 14/05/14 15:26:32 GMT FROM: Dmitry Svinkin at Ioffe Institute S. Golenetskii, R.Aptekar, D. Frederiks, V. Pal'shin, P. Oleynik, M. Ulanov, D. Svinkin, A. Tsvetkova, A.Lyssenko, and T. Cline on behalf of the Konus-Wind team, report: A long-duration GRB 140512A (Swift-BAT trigger 598819: Pagani et al., GCN 16249; Sakamoto et al., GCN 16258; Fermi-GBM detection: Stanbro, GCN 16262) triggered Konus-Wind at T0=70310.769 s UT (19:31:50.769). The light curve shows two separated multipeaked episodes: the first from ~T0-21 s to ~T0+12 s and the second longer and brighter from ~T0+88 s to ~T0+158 s. A total duration of the burst is ~179 s. As observed by Konus-Wind, the burst had a fluence of 4.8(-0.8,+2.0)x10^-5 erg/cm2, and a 256-ms peak flux, measured from T0+121.856 s, of 3.7(-1.2,+1.3)x10^-6 erg/cm2/s (both in the 20 keV - 10 MeV energy range). The time-averaged spectrum of the first bursting episode (measured from T0 to T0+8.448 s) is best fit in the 20 keV - 1.2 MeV range by a power law with exponential cutoff model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep) with alpha = -0.85 (-0.47,+0.61) and Ep = 279 (-69,+148) keV (chi2 = 62/60 dof). Fitting by a GRB (Band) model yields the same alpha and Ep, and an upper limit on the high energy photon index: beta < -2.1 (chi2 = 62/59 dof). The time-averaged spectrum of the second bursting episode (measured from T0+90.368 to T0+155.904 s) is best fit in the 20 keV - 6 MeV range by a power law with exponential cutoff model with the following parameters: alpha = -1.30 (-0.18,+0.21) and Ep = 466 (-124, +287) keV (chi2 = 79/79 dof). Fitting by a GRB (Band) model yields the same alpha and Ep, and an upper limit on the high energy photon index: beta < -1.9 (chi2 = 78/78 dof). The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB140512_T70310/ All the quoted errors are at the 90% confidence level. All the quoted values are preliminary.