TITLE: GCN CIRCULAR NUMBER: 14587 SUBJECT: Konus-Wind observation of GRB 130504C DATE: 13/05/06 11:08:40 GMT FROM: Dmitry Frederiks at Ioffe Institute S. Golenetskii, R.Aptekar, D. Frederiks, E. Mazets, V. Pal'shin, P. Oleynik, M. Ulanov, D. Svinkin, and T. Cline on behalf of the Konus-Wind team, report: The long-duration intense GRB 130504C (Fermi-LAT detection: Kocevski et al., GCN 14574; Fermi-GBM detection: Burgess et al., GCN 14583) triggered Konus-Wind at T0=84544.491s UT (23:29:04.491) The light curve shows multiple partly overlapped peaks from ~T0-15 s to ~T0+105s. The emission is seen up to 12 MeV. A possible hard precursor is seen in the 360-1400 keV light curve at ~T0-50s, but its attribution to GRB 130504C is yet unclear. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB130504_T84544/ As observed by Konus-Wind, the burst had a fluence of (2.0 ± 0.1)x10-4 erg/cm2, and a 64-ms peak flux, measured from T0+21.440s, of (2.6 ± 0.2)x10-5 erg/cm2/s (both in the 20 keV - 10 MeV energy range). The time-integrated spectrum (measured from T0 to T0+105.216 s) is best fit in the 20 keV - 15 MeV range by the GRB (Band) function with the following model parameters: the low-energy photon index alpha = -1.32 ± 0.04, the high energy photon index beta = -2.15 ± 0.1, the peak energy Ep = 452 ± 49 keV, chi2 = 110/97 dof. The spectrum at the maximum count rate (measured from T0+21.248 to T0+23.296 s) is best fit in the 20 keV - 15 MeV range by the GRB (Band) function with the following model parameters: the low-energy photon index alpha = -0.74 ± 0.12, the high energy photon index beta = -1.93 ± 0.06, the peak energy Ep = 251 ± 38 keV, chi2 = 61/66 dof. All the quoted results are preliminary.