{"paper":{"title":"Steps Toward Determination of the Size and Structure of the Broad-Line Region in Active Galactic Nuclei. XV. Long-Term Optical Monitoring of NGC 5548","license":"","headline":"","cross_cats":[],"primary_cat":"astro-ph","authors_text":"A.I. Shapovalova, A.J. Barth, A.N. Burenkov, A.V. Filippenko, B.J. Wilkes, B.M. Peterson, B. Nelson, D.C. Leonard, E.A. Sergeeva, E. Giannuzzo, F.-Z. Cheng, G.M. Stirpe, H. Wu, I. Wanders, J. Hunley, J. Peters, J.P. Huchra, J.-Y. Wei, K. Bischoff, L.C. Ho, M. Dietrich, M. Mignoli, N.G. Bochkarev, P. Berlind, P. Papaderos, R. Bertram, R.M. Wagner, R.W. Pogge, S.G. Sergeev, S.-J. Xue, S. Kaspi, S. Tokarz, T. Matheson, V.I. Pronik, W. Kollatschny, Yu.F. Malkov, Z.-L. Zou","submitted_at":"1998-08-21T17:30:40Z","abstract_excerpt":"We present the results of three years of ground-based observations of the Seyfert 1 galaxy NGC 5548, which combined with previously reported data, yield optical continuum and broad-line H-beta light curves for a total of eight years. The light curves consist of over 800 points, with a typical spacing of a few days between observations. During this eight-year period, the nuclear continuum has varied by more than a factor of seven, and the H-beta emission line has varied by a factor of nearly six. The H-beta emission line responds to continuum variations with a time delay or lag of 10-20 days, t"},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"astro-ph/9808236","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":""},"integrity":{"clean":true,"summary":{"advisory":0,"critical":0,"by_detector":{},"informational":0},"endpoint":"/pith/astro-ph/9808236/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"}