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Steps toward Determination of the Size and Structure of the Broad-Line Region in Active Galactic Nuclei. XI. Intensive Monitoring of the Ultraviolet Spectrum of NGC 7469
From 1996 June 10 to July 29, the International Ultraviolet Explorer monitored the Seyfert 1 galaxy NGC 7469 continuously in an attempt to measure time delays between the continuum and emission-lineExpand
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Intermediate resolution Hβ spectroscopy and photometric monitoring of 3C 390.3 I. Further evidence of a nuclear accretion disk
We have monitored the AGN 3C 390.3 between 1995 and 2000. A historical B-band light curve dating back to 1966 shows a large increase in brightness during 1970{1971, followed by a gradual decreaseExpand
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Long-term variability of the optical spectra of NGC 4151 - II. Evolution of the broad Hα and Hβ emission-line profiles
Aims. We present the results of a long-term monitoring (11 years, between 1996 and 2006) of Hα and Hβ line variations of the active galactic nucleus of NGC 4151. Methods. High quality spectra (S /N >Expand
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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
We present the results of 3 yr of ground-based observations of the Seyfert 1 galaxy NGC 5548, which, combined with previously reported data, yield optical continuum and broad-line Hβ light curves forExpand
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Long-term variability of the optical spectra of NGC 4151. I. Light curves and flux correlations
Aims. Results of long-term spectral monitoring of the active galactic nucleus of NGC 4151 are presented (11 years, from 1996 to 2006). Methods. High quality spectra (S /N > 50 in the continuum nearExpand
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Spectral optical monitoring of 3C 390.3 in 1995–2007 - I. Light curves and flux variation in the continuum and broad lines
Context. We present the results of the long-term (1995-2007) spectral monitoring of the broad-line radio galaxy 3C 390.3, a well known AGN with double-peaked broad emission lines, usually assumed toExpand
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The First Spectroscopically Resolved Sub-parsec Orbit of a Supermassive Binary Black Hole
One of the most intriguing scenarios proposed to explain how active galactic nuclei are triggered involves the existence of a supermassive binary black hole (BH) system in their cores. Here, weExpand
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Spectral optical monitoring of a double-peaked emission line AGN Arp 102B Variability of spectral lines and continuum
Context. We present results of long-term (1987‐2010) optical spectral monitoring of the broad-line radio galaxy Arp 102B, a prototype of an active galactic nucleus with double-peaked broad emissionExpand
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Spectral optical monitoring of the double-peaked emission line AGN Arp 102B - II. Variability of the broad line properties
We investigate a long-term (26 years, from 1987 to 2013) variability in the broad spectral line properties of the radio galaxy Arp 102B, an active galaxy with broad double-peaked emission lines. WeExpand
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Steps toward determination of the size and structure of the broad-line region in active nuclei. 7: Variability of the optical spectrum of NGC 5548 over years
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 1990Expand
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