TITLE: GCN CIRCULAR NUMBER: 35256 SUBJECT: Konus-Wind detection of GRB 231129C DATE: 23/12/04 15:14:55 GMT FROM: Alexandra Lysenko at Ioffe Institute alexandra.lysenko@mail.ioffe.ru
A. Lysenko, D. Frederiks, A. Ridnaia, D. Svinkin, A. Tsvetkova, M. Ulanov, and T. Cline on behalf of the Konus-Wind team, report:
The bright long-duration GRB 231129C (Fermi-GBM detection: Sharma et al., GCN Circ. 35227; MAXI/GSC detection: Kawakubo et al., GCN Circ. 35223; CALET detection: Kawakubo et al., GCN Circ. 35228; AstroSat CZTI detection: Waratkar et al., GCN Circ. 35230; GECAM-B detection: Zheng et al., GCN Circ. 35231; Swift-XRT detection: Gropp et al., GCN Circ. 35234; Glowbug detection: Cheung et al., GCN Circ. 35235; GRBAlpha detection: Dafcikova et al., GCN Circ. 35236; Fermi-LAT detection: Arimoto et al., GCN Circ. 35238; AGILE detection: Panebianco et al., GCN Circ. 35244) triggered Konus-Wind at T0=69016.319 s UT (19:10:16.319).
The burst light curve shows a bright, multi-peaked pulse featuring a very strong hard-to-soft spectral evolution. The pulse starts at ~T0-0.2 and has a total duration of ~9.6 s. The emission is seen up to ~15 MeV.
The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB231129_T69016/
As observed by Konus-Wind, the burst had a fluence of 8.60(-0.23,+0.24)x10^-5 erg/cm2, and a 64-ms peak flux, measured from T0+0.106s, of 4.16(-0.52,+0.54)x10^-5 erg/cm2/s (both in the 20 keV - 10 MeV energy range).
The time-averaged spectrum of the burst (measured from T0 to T0+12.800 s) is best fit in the 20 keV - 20 MeV range by the GRB (Band) model with the following parameters: the low-energy photon index alpha = -0.17(-0.06,+0.06), the high energy photon index beta = -2.95(-0.12,+0.10), the peak energy Ep = 202(-6,+6) keV (chi2 = 151/97 dof).
The spectrum near the maximum count rate (measured from T0 to T0+0.256 s) is best fit in the 20 keV - 20 MeV range by a power law with exponential cutoff model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep) with alpha = -0.20(-0.14,+0.15) and Ep = 782(-52,+55) keV (chi2 = 69/51 dof). Fitting by a GRB (Band) model yields the same alpha and Ep, and an upper limit on the high energy photon index: beta < -3.3 (chi2 = 69/50 dof).
All the quoted errors are at the 90% confidence level. All the quoted values are preliminary.
View this GCN Circular online at https://gcn.nasa.gov/circulars/35256. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...