1998/02/09 by Bradley M. Peterson, B. M. Peterson, Ignaz Wanders +7 · 6 citations
Decision Sciences · Physics and Astronomy · #Astronomy and Astrophysical Research #Scientific Measurement and Uncertainty Evaluation #Scientific Research and Discoveries #astro-ph
paper · pdf · doi:10.1086/305813
24 pages, 16 figures. Accepted for publication in ApJ
arxiv created 1998/02/09 · openalex publication_date 1998/07/01 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/01
We present the light curves obtained during an 8 yr program of optical spectroscopic monitoring of nine Seyfert 1 galaxies: 3C 120, Akn 120, Mrk 79, Mrk 110, Mrk 335, Mrk 509, Mrk 590, Mrk 704, and Mrk 817. All objects show significant variability in both the continuum and emission-line fluxes. We use cross-correlation analysis to derive the sizes of the broad Hβ-emitting regions based on emission-line time delays, or lags. We successfully measure time delays for eight of the nine sources and find values ranging from about 2 weeks to a little over 2 months. Combining the measured lags and widths of the variable parts of the emission lines allows us to make virial mass estimates for the active nucleus in each galaxy. The virial masses are in the range 10 7 -10 8 M ☉ .