TITLE: GCN CIRCULAR NUMBER: 39721 SUBJECT: Konus-Wind detection of GRB 250313A DATE: 25/03/14 16:07:45 GMT FROM: Dmitry Frederiks at Ioffe Institute fred@mail.ioffe.ru
D. Frederiks, A.Lysenko, A. Ridnaia, D. Svinkin, A. Tsvetkova, M. Ulanov, and T. Cline, on behalf of the Konus-Wind team, report:
The long GRB 250313A (Fermi-GBM detection: Fermi GBM team, GCN 39703; BALROG localization: Preis & Greiner, GCN 39704; Fermi-LAT detection: Di Lalla et al., GCN 39711; AstroSat CZTI detection: Dasgupta et al., GCN 39714; SVOM/GRM observation: Wang et al., GCN 39716) triggered Konus-Wind (KW) at T0=52473.618 s UT (14:34:33.618).
The burst light curve shows a bright, multi-peaked emission pulse, with the duration of ~15 s, followed by a broad, weaker pulse, peaked at T0+270 s. The total duration of the burst is ~345 s. The emission is seen up to ~1.5 MeV.
The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB250313_T52473/
As observed by Konus-Wind, the burst had a fluence of (1.06 ± 0.19)x10^-4 erg/cm^2 and a 64-ms peak energy flux, measured from T0 + 7.936 s, of (1.23 ± 0.10)x10^-5 erg/cm^2/s (both in the 20 keV - 10 MeV energy range).
The time-integrated spectrum (measured from T0 to T0+345 s) is best fit in the 20 keV - 1.5 MeV range by a GRB (Band) function with the following model parameters: the low-energy photon index alpha = -1.13 (-0.04,+0.04), the high energy photon index beta = -2.64 (-0.73,+0.21), the peak energy Ep = 237 (-15,+18) keV, chi2 = 34/63 dof.
The spectrum near the peak count rate (measured from T0+7.936 s to T0+8.960 s) is best fit in the 20 keV - 1.5 MeV range by a GRB (Band) function with the following model parameters: the low-energy photon index alpha = -0.52 (-0.07,+0.08), the high energy photon index beta = -2.80 (-0.41,+0.25), the peak energy Ep = 294 (-20,+21) keV, chi2 = 34/51 dof.
All the quoted errors are estimated at the 68% confidence level. All the presented results are preliminary.
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