Peterson, B. M.Berlind, PerryBertram, R.Bischoff, K.Bochkarev, N. G.Borisov, N.Burenkov, A. N.Calkins, MichaelCarrasco, L.Chavushyan, V. H.Chornock, RDietrich, M.Doroshenko, V. T.Ezhkova, O. V.Filippenko, A. V.Gilbert, A. M.Huchra, J. P.Kollatschny, W.Leonard, D. C.Li, W.Lyuty, V. M.Malkov, Yu. F.Matheson, T.Merkulova, N. I.Mikhailov, V. P.Modjaz, M.Onken, C. A.Pogge, R. W.Pronik, V. I.Qian, B.Romano, P.Sergeev, S. G.Sergeeva, E. A.Shapovalova, A. I.Spiridonova, O. I.Tao, J.Tokarz, S.Valdes, J. R.Vlasiuk, V. V.Wagner, R. M.Wilkes, Belinda2017-02-142002Peterson, B. M., P. Berlind, R. Bertram, K. Bischoff, N. G. Bochkarev, N. Borisov, A. N. Burenkov, et al. 2002. “Steps Toward Determination of the Size and Structure of the Broad‐Line Region in Active Galactic Nuclei. XVI. A 13 Year Study of Spectral Variability in NGC 5548.” The Astrophysical Journal 581 (1) (December 10): 197–204. doi:10.1086/344197.0004-637Xhttp://nrs.harvard.edu/urn-3:HUL.InstRepos:30239240We present the final installment of an intensive 13 year study of variations of the optical continuum and broad Hβ emission line in the Seyfert 1 galaxy NGC 5548. The database consists of 1530 optical continuum measurements and 1248 Hβ measurements. The Hβ variations follow the continuum variations closely, with a typical time delay of about 20 days. However, a year-by-year analysis shows that the magnitude of emission-line time delay is correlated with the mean continuum flux. We argue that the data are consistent with the simple model prediction between the size of the broad-line region and the ionizing luminosity, r ∝ Lion. Moreover, the apparently linear nature of the correlation between the Hβ response time and the nonstellar optical continuum Fopt arises as a consequence of the changing shape of the continuum as it varies, specifically Fopt ∝ FUV.en-USGalaxies: activegalaxies: individual (NGC 5548)Galaxies: nucleiGalaxies: SeyfertJournal Article2017-02-1410.1086/344197