{"paper":{"title":"Spectroscopic Observations and Analysis of the Unusual Type Ia SN 1999ac","license":"","headline":"","cross_cats":[],"primary_cat":"astro-ph","authors_text":"A. Amadon, A. Conley, A. G. Kim, A. Goobar, A. L. Spadafora, A. Mourao, B. C. Lee C. Lidman, B. E. Schaefer, B. Frye, B. Goldman, C. Balland, D. A. Howell, D. E. Groom, D. Hardin, E. L. Gates, E. Smith, G. Aldering, G. Blanc, G. Folatelli, G. Goldhaber, G. J. Miller, G. T. Richards, H. Newberg, I. Hook, J. Haissinski, J. Mendez, J. Rich, K. Schahmaneche, L. Wang, M. Kowalski, M. Moniez, M. Mouchet, N. A. Walton, N. Kuznetsova, N. Regnault, O. Perdereau, P. Astier, P. E. Nugent, P. Ruiz-Lapuente, R. A. Knop, R. Amanullah, R. C. Thomas, R. Ellis S. Fabbro, R. Gibbons, R. Pain, R. Quimby, S. E. Deustua, S. Kent, S. Nobili, S. Perlmutter, T. Dahlen, The Supernova Cosmology Project: G. Garavini, V. Fadeyev, V. Stanishev, W. M. Wood-Vasey, X. Fan","submitted_at":"2005-07-12T14:04:54Z","abstract_excerpt":"We present optical spectra of the peculiar Type Ia supernova (SN Ia) 1999ac. The data extend from -15 to +42 days with respect to B-band maximum and reveal an event that is unusual in several respects. Prior to B-band maximum, the spectra resemble those of SN 1999aa, a slowly declining event, but possess stronger SiII and CaII signatures (more characteristic of a spectroscopically normal SN). Spectra after B-band maximum appear more normal. The expansion velocities inferred from the Iron lines appear to be lower than average; whereas, the expansion velocity inferred from Calcium H and K are hi"},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"astro-ph/0507288","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"}