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8 papers · 2 filters
Quasi-Periodic Oscillation in Seyfert galaxies: Significance levels. The Case of Mrk 766
S. Benlloch, J. Wilms, R. Edelson +2
We discuss methods to compute significance levels for the existence of quasi-periodic oscillations (QPOs) in Active Galactic Nuclei (AGN) which take the red-noise character of the…
X-ray Spectral Variability and Rapid Variability of the Soft X-ray Spectrum Seyfert 1 Galaxies Ark 564 and Ton S180
Rick Edelson, T. J. Turner, Ken Pounds +5
The bright, soft X-ray spectrum Seyfert 1 galaxies Ark 564 and Ton S180 were monitored for 35 days and 12 days with ASCA and RXTE (and EUVE for Ton S180). The short time scale (hou…
Multiwavelength Monitoring of the Narrow-Line Seyfert 1 Galaxy Akn 564. II. Ultraviolet Continuum and Emission-line Variability
S. Collier, D. M. Crenshaw, B. M. Peterson +15
We present results of an intensive two-month campaign of approximately daily spectrophotometric monitoring of the narrow-line Seyfert 1 galaxy Akn 564 with HST. The fractional vari…
Multiwavelength Monitoring of the Narrow-Line Seyfert 1 Galaxy Akn 564. I. ASCA Observations and the Variability of the X-ray Spectral Components
T. J. Turner, P. Romano, I. M. George +4
We present a 35 day ASCA observation of the NLS1 Akn 564, which was part of a multiwavelength AGN Watch monitoring campaign. Akn 564 shows a photon index varying across the range 2…
A complete sample of Seyfert galaxies selected at 1/4 keV
S. Vaughan, R. Edelson, R. S. Warwick +2
We have used the ROSAT Bright Source Catalogue to extract a complete sample of sources selected in the band from 0.1-0.4 keV. This 1/4 keV-selected sample is comprised of 54 Seyfer…
High Temporal Resolution XMM Monitoring of PKS 2155-304
Rick Edelson, Gareth Griffiths, Alex Markowitz +3
The bright, strongly variable BL Lac object PKS 2155-304 was observed by XMM for two essentially uninterrupted periods of ~11 and 16 hr on 30-31 May 2000. The strongest variations…
Monitoring of the optical and 2.5-11.7 micron spectrum and mid-IR imaging of the Seyfert 1 galaxy Mrk279 with ISO
The AGN Watch collaboration, M. Santos-Lleo, J. Clavel +19
Mid-infrared images of the Seyfert 1 galaxy Mrk 279 obtained with the ISO satellite are presented together with the results of a one-year monitoring campaign of the 2.5-11.7 micron…
X-ray Power Density Spectrum of the Narrow Line Seyfert 1 Galaxy Akn 564
Ken Pounds, Rick Edelson, Alex Markowitz +1
Beginning in 1999 January, the bright, strongly variable Narrow-Line Seyfert 1 (NLS1) galaxy Akn 564 has been observed by RXTE once every ~4.3 days. It was also monitored every ~3.…