Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: ASCA observations of Seyfert 1 galaxies: I. Data Analysis, Imaging and
  Timing   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 AGN. All but
one of the Seyferts show evidence for variability on timescales of
minutes-hours, with the amplitude anti-correlated with the source luminosity,
confirming previous results. In at least 8 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. Ultra-rapid variability, implying significant power at frequencies $>
10^{-3}$~Hz is detected in at least 5 sources, but is difficult to detect in
most cases, due to 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 time scales.

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The categories of this paper are: mtrl-th
12
The categories of this paper are: nucl-th
5
The categories of this paper are: gr-qc
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The categories of this paper are: cmp-lg
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The categories of this paper are: alg-geom
11
The categories of this paper are: hep-lat
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The categories of this paper are: dg-ga
15
The categories of this paper are: nucl-ex
14
The categories of this paper are: math-ph
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The categories of this paper are: ao-sci
10
The categories of this paper are: q-bio
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The categories of this paper are: funct-an
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The categories of this paper are: q-fin
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The categories of this paper are: chao-dyn
1
The categories of this paper are: cs
16
The categories of this paper are: stat