Carone, T. E.Peterson, B. M.Bechtold, J.Bertram, R.Bischoff, K.Dietrich, M.Filppenko, A. V.Ho, L. C.Huchra, JohnKollatchny, W.Korista, K. T.Matheson, T.Pogge, R. W.Shields, J. C.Smith, P. S.Wagner, R. M.Wilkes, Belinda2017-02-131996Carone, T. E., B. M. Peterson, J. Bechtold, R. Bertram, K. Bischoff, M. Dietrich, A. V. Filppenko, et al. 1996. “Optical Continuum and Emission‐Line Variability of the Seyfert 1 Galaxy Markarian 509.” The Astrophysical Journal 471 (2) (November 10): 737–747. doi:10.1086/178002.0004-637Xhttp://nrs.harvard.edu/urn-3:HUL.InstRepos:30212161We report on the results of a 5 year coordinated program of spectroscopic monitoring of the luminous Seyfert 1 galaxy Markarian 509. The Hβ and He II λ4686 emission lines are found to respond to continuum variations with time lags of ~80 and ~60 days, respectively, considerably longer than the emission-line lags measured for other Seyfert galaxies.en-USGalaxies: activeGalaxies: individual (Markarian 509)Galaxies: SeyfertJournal Article2017-02-1310.1086/178002