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Date and Time of the Query: 2019-06-24 T11:49:42 PDT
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For refcode 1997ApJ...476...70N:
Retrieve 18 NED objects in this reference.
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Copyright by American Astronomical Society. Reproduced by permission
1997ApJ...476...70N ASCA Observations of Seyfert 1 Galaxies. I. Data Analysis, Imaging, and Timing K. NANDRA, I. M. GEORGE, R. F. MUSHOTZKY, T. J. TURNER, AND T. YAQOOB Received 1996 March 25; accepted 1996 September 3 ABSTRACT We present the first in a series of papers describing the X-ray properties of a sample of 18 Seyfert 1 galaxies, using data obtained by ASCA. The imaging data reveal a number of serendipitous hard X-ray sources in some source fields, but none contribute significantly to the hard X-ray flux of the active galactic nuclei. All but one of the Seyferts show evidence for variability on timescales of minutes to hours, with the amplitude anticorrelated with the source luminosity, confirming previous results. In at least eight sources there is evidence that the variability amplitude below 2 keV is greater than that in the hard X-ray band, perhaps indicating variable components other than the power law in the soft band. Ultrarapid variability, implying significant power at frequencies greater than 10-3 Hz is detected in at least five sources but is difficult to detect in most cases, because of the sampling and signal- to-noise ratio. In Mrk 766 and MCG -6-30-15 there is also an indication that the high-frequency power spectra are variable in shape and/or intensity. There is similar evidence in NGC 4151 but on longer timescales. Subject headings: galaxies: active-galaxies: nuclei-galaxies: Seyfert-X- rays: galaxies
Retrieve 18 NED objects in this reference.
Please click here for ADS abstract

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