TITLE: GCN CIRCULAR NUMBER: 46270 SUBJECT: GRB 261113A: SVOM/ECLAIRs refined analysis DATE: 26/11/14 11:35:24 GMT FROM: SVOM_group Authors: N. Dagoneau, A. Saccardi, S. Bisero (CEA) report on behalf of the SVOM/ECLAIRs team Using the event-by-event data downloaded through the X-band ground station, we report further analysis of SVOM/ECLAIRs observations of GRB 261113A (SVOM burst-id sb26111302 - GCN 46244, trigger time T0 = 2026-11-13T14:31:02 UTC). The burst that triggered ECLAIRs onboard shows a multiple narrow peak structure. The burst duration is T90 = 7.8 -0.1 / +0.1 in the 4-120 keV energy band. The time-averaged spectrum from T0-0.68 s to T0+7.16 s in the 5-120 keV energy range is best fitted by a cutoff power law model with a power-law index alpha = -0.61 ± 0.05 and peak energy of 108 ± 10. With this model, the 4-120 keV fluence is (2.81 ± 0.09)e-6 erg/cm^2 and the 4-120 keV photon flux is 6.89 ± 0.15 ph/cm^2/s. Assuming a redshift of z=3.580 (GCN 46261) and a standard cosmology with H_0 = 67.3 km/s/Mpc and Omega_M = 0.315 (Planck Collaboration, 2014), we estimate the following rest-frame parameters: the isotropic energy released Eiso is (1.10 +/- 0.09)e53 erg, and the rest-frame peak energy of the time-averaged spectrum Ep,z is 495 keV. With these estimates, GRB 261113A is consistent with the distribution of Type II (collapsar-like) GRBs on the Amati relation reported by Willingale et al. 2017. All the quoted errors are at the 68% confidence level. The Space-based multi-band astronomical Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA), French Space Agency (CNES), and the Chinese Academy of Sciences (CAS), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. ECLAIRs was developed jointly by CNES, CEA-IRFU, CNRS-IRAP, CNRS-APC. The SVOM/ECLAIRs point of contact for this burst is: Nicolas Dagoneau (CEA) (nicolas.dagoneau at cea.fr)