TITLE: GCN CIRCULAR NUMBER: 5848 SUBJECT: GRB 061121: Ep,i - Eiso correlation DATE: 06/11/24 00:40:19 GMT FROM: Lorenzo Amati at INAF-IASF/Bologna L. Amati (INAF-IASF Bologna), F. Frontera (Univ.Ferrara and INAF-IASF Bologna), C. Guidorzi (Univ.Bicocca/INAF and Osservatorio Astronomico di Brera), E. Montanari (Univ.Ferrara) and M. Della Valle (INAF-Osservatorio Astrofisico di Arcetri) report: "Based on the redshift of 1.314 (GCN 5826) and the fluence and spectral properties of the prompt emission as measured by Konus-Wind (GCN 5837) and RHESSI (GCN 5838), we estimate for GRB 061121 a total isotropic released energy, Eiso, of ~(3+/-0.3)x10^(53) erg (1-10000 keV cosmological rest-frame, H0=65 km/s/Mpc, Omega_m=0.3, Omega_lambda=0.7) and an intrinsic peak energy, Ep,i, of ~1200+/-400 keV. These values are consistent with the best fit of the Ep,i-Eiso correlation within ~0.9 - 2.3 sigma (see, e.g., Figure 1 of Amati et al. 2006, astro-ph/0607148v4). Given that the Konus-Wind and RHESSI spectra were measured during the brighter and harder portion of the event (~20s), the inclusion in the spectral analysis of the BAT and XRT data covering the whole prompt emission (i.e. up to ~120 s from the Swift trigger, see GCN Report 15.1) may provide a lower value of Ep,i and a slightly higher value of Eiso, improving the match with the Ep,i-Eiso correlation." This message may be cited.