TITLE: GCN CIRCULAR NUMBER: 43981 SUBJECT: GRB 260310A / AT 2026fgk: Location in the Epeak - Eiso diagram DATE: 26/03/13 08:04:42 GMT FROM: Jean-Luc Atteia at IRAP <jean-luc.atteia@irap.omp.eu> Jean-Luc Atteia (IRAP), Enrique Moreno Méndez (UNAM), Massimiliano Lincetto (CPPM), Damien Dornic (CPPM), Rosa L. Becerra (UNAM), Alan M. Watson (UNAM), Camila Angulo (UNAM), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Edilberto Aguilar-Ruiz (UNAM), Dalya Akl (NYUAD), Sarah Antier (IJCLAB), Nathaniel R. Butler (ASU), Jean-Grégoire Ducoin (CPPM), Francis Fortin (IRAP), Leonardo García García (UNAM), Ramandeep Gill (UNAM), Noémie Globus (UNAM), Marion Guelfand (CPPM), Asuka Kuwata (UNAM), Nikos Mandarakas (LAM), Diego López-Cámara (UNAM), Francesco Magnani (CPPM), Margarita Pereyra (UNAM), Ny Avo Rakotondrainibe (LAM), Fredd Sánchez Álvarez (UNAM), Benjamin Schneider (LAM), and Antonio de Ugarte Postigo (LAM) report: we computed the isotropic equivalent energy of GRB 260310A (Fermi GBM Team, GCN Circ. 43951) , using the spectral information on the prompt emission measured by Fermi GBM (Hamburg & Meegan, GCN Circ. 43975), in order to locate the GRB in the Amati diagram. At z = 0.153 (Hinds et al. GCN 43977), Ep,i = 198 keV, Eiso = 3.5e50 erg and GRB 260310A clearly lies in the Type I (mergers) region of the Amati plot, which is unusual for a long GRB. In order to locate GRB 260310A in the Type II (collapsars) region of the Amati plot, it has to be at z ≥ 0.7, and not associated with the bright galaxy noticed by the LAST team (Konno et al., GCN Circ. 43974). View this GCN Circular online at https://gcn.nasa.gov/circulars/43981. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...