{"paper":{"title":"The extraordinarily bright optical afterglow of GRB 991208 and its host galaxy","license":"","headline":"","cross_cats":[],"primary_cat":"astro-ph","authors_text":"A. Henden, A. J. Castro-Tirado, A.K. Pandey, A. Magazzu, A. Shlyapnikov, A.V. Moiseev, B.L. Jensen, B. Stecklum, C. Blake, C. Kouveliotou, D. Hartmann, D. Heinlein, E. Palazzi, E. Pian, E. Rol, E. Xanthopoulos, F. Ghinassi, G. Feulner, H. Boehnhardt, H.E. Kristen, H. Hurley, H. Pedersen, J. Gorosabel, J. Greiner, J. Hjorth, J. Marti, J. M. Castro Cer\\'on, J.M. Paredes, J. Smoker, J. Wall, L. Tommasi, M. Bremer, M.R. Zapatero-Osorio, N. Caon, N. Masetti, P. Vreeswijk, R.A.M.J. Wijers, R. Hudec, R. Sagar, S. Benetti, S.B. Pandey, S. Dreizler, S. Guziy, S. Klose, S.N. Dodonov, S. Toft, T.A. Fatkhullin, U. Hopp, V.L. Afanasiev, V. Mohan, V.N. Komarova, V. Simon, V. V. Sokolov","submitted_at":"2001-02-09T22:33:50Z","abstract_excerpt":"Observations of the extraordinarily bright optical afterglow (OA) of GRB 991208 started 2.1 d after the event. The flux decay constant of the OA in the R-band is -2.30 +/- 0.07 up to 5 d, which is very likely due to the jet effect, and after that it is followed by a much steeper decay with constant -3.2 +/- 0.2, the fastest one ever seen in a GRB OA. A negative detection in several all-sky films taken simultaneously to the event implies either a previous additional break prior to 2 d after the occurrence of the GRB (as expected from the jet effect). The existence of a second break might indica"},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"astro-ph/0102177","kind":"arxiv","version":2},"verdict":{"id":null,"model_set":{},"created_at":null,"strongest_claim":"","one_line_summary":"","pipeline_version":null,"weakest_assumption":"","pith_extraction_headline":""},"integrity":{"clean":true,"summary":{"advisory":0,"critical":0,"by_detector":{},"informational":0},"endpoint":"/pith/astro-ph/0102177/integrity.json","findings":[],"available":true,"detectors_run":[],"snapshot_sha256":"c28c3603d3b5d939e8dc4c7e95fa8dfce3d595e45f758748cecf8e644a296938"},"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"}