D. M. Crenshaw

Multiwavelength Observations of Short-Timescale Variability in NGC 4151. IV. Analysis of Multiwavelength Continuum Variability

This paper combines data from the three preceding papers in order to analyze the multi-waveband variability and spectral energy distribution of the Seyfert~1 galaxy NGC~4151 during the December 1993 monitoring campaign. The source, which was near its peak historical brightness, showed strong, correlated variability at X-ray, ultraviolet, and optical wavelengths. The strongest variations were seen in medium energy (

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

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Steps toward determination of the size and structure of the broad-line region in active galactic nuclei. 5: Variability of the ultraviolet continuum and emission lines of NGC 3783

1.5~keV) X-rays, with a normalized variability amplitude (NVA) of 24%. Weaker (NVA = 6%) variations (uncorrelated with those at lower energies) were seen at soft

Steps toward determination of the size and structure of the broad-line region in active galactic nuclei. IX. Ultraviolet observations of Fairall 9

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A Kinematic Model for the Narrow-Line Region in NGC 4151*

-ray energies of

Steps toward Determination of the Size and Structure of the Broad-Line Region in Active Galactic Nuclei. XIII. Ultraviolet Observations of the Broad-Line Radio Galaxy 3C 390.3

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Space Telescope Imaging Spectrograph Long-Slit Spectroscopy of the Narrow-Line Region of NGC 4151. II. Physical Conditions along Position Angle 221° *

100~keV. No significant variability was seen in softer (0.1--1~keV) X-ray bands. In the ultraviolet/optical regime, the NVA decreased from 9% to 1% as the wavelength increased from 1275~AA to 6900~AA. These data do not probe extreme ultraviolet (1200~AA to 0.1~keV) or hard X-ray (2--50~keV) variability. The phase differences between variations in different bands were consistent with zero lag, with upper limits of

The Variability and Spectrum of NGC 5548 in the Extreme Ultraviolet

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Space Telescope Imaging Spectrograph Long-Slit Spectroscopy of the Narrow-Line Region of NGC 4151. I. Kinematics and Emission-Line Ratios

0.15~day between 1275~AA and the other ultraviolet bands,

MULTIWAVELENGTH MONITORING OF THE NARROW-LINE SEYFERT 1 GALAXY ARAKELIAN 564. II. ULTRAVIOLET CONTINUUM AND EMISSION-LINE VARIABILITY

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