• Steps toward determination of the size and structure of the broad-line region in active galactic nuclei. VII. Variability of the optical spectrum of NGC 5548 over 4 years 

      Peterson, Bradley M.; Berlind, P.; Bertram, R.; Bochkarev, N.G.; Bond, D.; Brotherton, Mike; Busler, J.R.; Chuvaev, K.K.; Cohen, R.D.; Dietrich, Matthias; Elvis, Martin; Filippenko, Alexei V.; Foltz, C.B.; Garnavich, P.M.; Ho, Luis C.; Horine, E.; Horne, Keith; Huchra, John P.; Kollatschny, W.; Korista, Kirk T.; Malkan, M.A.; Matheson, T.; Mignoli, M.; Morris, S.L.; Nazarova, L.; Penfold, J.; Peters, J.; Pogge, Richard William; Pronik, V.I.; Rush, B.; Sergeev, S.G.; Shapovalova, A.I.; Shields, J.C.; Stirpe, Giovanna M.; Tokarz, S.; Wagner, R.M.; Weymann, R.J.; White, R.J.; Wilkes, B.J.; Wills, Derek; Wills, Beverley J.; Winge, Claudia; Younger, P.F. (1994) [Artigo de periódico]
      We report on the results of a continuation of a large monitoring program of optical spectroscopy of the Seyfert 1 galaxy NGC 5548. The new observations presented here were obtained between 1990 December and 1992 October, ...