{"paper":{"title":"The afterglow onset for GRB060418 and GRB060607A","license":"","headline":"","cross_cats":[],"primary_cat":"astro-ph","authors_text":"A. Monfardini, A. Pizarro, D. Guetta, D. Malesani, D. Rizzuto, E.J.A. Meurs, E. Molinari, E. Palazzi, E. Pian, F. D'Alessio, F.M. Zerbi, F. Vitali, G. Chincarini, G. Ihle, G. Malaspina, G. Tagliaferri, G. Tosti, J. Valenzuela, L.A. Antonelli, L. Gonzalez, L. Nicastro, L. Norci, L. Stella, M. Stefanon, N. Masetti, P.A. Ward, P. Conconi, P. D'Avanzo, P. Goldoni, P. Sinclair, S. Campana, S. Covino, S.D. Vergani, S. Piranomonte, V. Testa","submitted_at":"2007-10-03T08:04:46Z","abstract_excerpt":"Gamma-ray burst are thought to be produced by highly relativistic outflows. Although upper and lower limits for the outflow initial Lorentz factor $\\Gamma_0$ are available, observational efforts to derive a direct determination of $\\Gamma_0$ have so far failed or provided ambiguous results. As a matter of fact, the shape of the early-time afterglow light curve is strongly sensitive on $\\Gamma_0$ which determines the time of the afterglow peak, i.e. when the outflow and the shocked circumburst material share a comparable amount of energy. We now comment early-time observations of the near-infra"},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"0710.0727","kind":"arxiv","version":1},"verdict":{"id":null,"model_set":{},"created_at":null,"strongest_claim":"","one_line_summary":"","pipeline_version":null,"weakest_assumption":"","pith_extraction_headline":""},"references":{"count":0,"sample":[],"resolved_work":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57","internal_anchors":0},"formal_canon":{"evidence_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"author_claims":{"count":0,"strong_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"builder_version":"pith-number-builder-2026-05-17-v1"}