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The Cambridge-Cambridge ROSAT Serendipity Survey -- V. Catalogue and optical identifications
(Oxford University Press (OUP), 1997)
We report the results of a medium-depth X-ray survey of 20 ROSAT Position Sensitive Proportional Counter (PSPC) fields. 123 X-ray sources were detected down to a flux limit of S(0.5–2 keV) > 2 × 10−14 erg s−1 cm−2 lying ...
Multiwavelength Observations of Short-Timescale Variability in NGC 4151. I. Ultraviolet Observations
(IOP Publishing, 1996)
We present the results of an intensive ultraviolet monitoring campaign on the Seyfert I galaxy NGC 4151, as part of an effort to study its short-timescale variability over a broad range in wavelength. The nucleus of NGC ...
Optical Detection of the Hidden Nuclear Engine in NGC 4258
(IOP Publishing, 1995)
The subparsec masing disk recently found to be orbiting a central mass of ~3.6 × 107 M☉ in the Seyfert/LINER galaxy NGC 4258 (Miyoshi and coworkers) provides the most compelling evidence to date for the existence of a ...
The Cambridge-Cambridge ROSAT Serendipity Survey -- IV. The X-ray properties
(Oxford University Press (OUP), 1997)
We present a detailed X-ray spectral analysis in the 0.1–2.4 keV ROSAT band of a complete sample of X-ray-selected AGN using the 80 AGNs in the Cambridge-Cambridge ROSAT Serendipity Survey (68 QSOs and 12 narrow-emission-line ...
Testing Unified X-Ray/Ultraviolet Absorber Models with NGC 5548
(IOP Publishing, 1995)
The bright Seyfert galaxy NGC 5548 shows absorption features in its X-ray and UV spectra. The large amount of optical/UV and X-ray monitoring data available for this object makes it an ideal candidate to test our model of ...
The Soft X‐Ray Properties of a Complete Sample of Optically Selected Quasars. II. Final Results
(IOP Publishing, 1997)
We present the final results of a ROSAT PSPC program to study the soft X-ray emission properties of a complete sample of low-z quasars. This sample includes all 23 quasars from the Bright Quasar Survey with z ≤ 0.400 and ...
Optical Continuum and Emission‐Line Variability of the Seyfert 1 Galaxy Markarian 509
(IOP Publishing, 1996)
We 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 ...
Investigation of the Relation between the Spectral Energy Distributions and the Emission Lines in Low‐Redshift Quasars
(IOP Publishing, 1999)
We investigate the relations between the observed emission-line strengths, widths, and continuum properties of a sample of 41 low-redshift (z<1) quasars for which contemporaneous IR/soft X-ray spectral energy distributions ...
Steps toward Determination of the Size and Structure of the Broad‐Line Region in Active Galactic Nuclei. IX. Ultraviolet Observations of Fairall 9
(IOP Publishing, 1997)
An 8 month monitoring campaign on the Seyfert 1 galaxy Fairall 9 has been conducted with the International Ultraviolet Explorer in an attempt to obtain reliable estimates of continuum-continuum and continuum-emission-line ...
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
(IOP Publishing, 1999)
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 for a total of 8 yr. The ...