Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: X-ray observations of NGC 1365: time-resolved eclipse of the X-ray
  source   We present an extraordinary variation of the X-ray spectrum of the obscured
AGN in NGC 1365, which was observed by Chandra to change from Compton-thin to
Compton-thick and back to Compton-thin in four days. This fast variation imply
a a size of ~10^14 cm for the emitting region, and an extremely compact size
(~10^16 cm) of the clumpy circumnuclear absorber.

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The categories of this paper are: plasm-ph
0
The categories of this paper are: hep-ph
1
The categories of this paper are: cs
24
The categories of this paper are: dg-ga
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The categories of this paper are: atom-ph
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The categories of this paper are: alg-geom
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The categories of this paper are: hep-th
11
The categories of this paper are: hep-lat
17
The categories of this paper are: q-fin
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The categories of this paper are: funct-an
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The categories of this paper are: mtrl-th
16
The categories of this paper are: stat
23
The categories of this paper are: solv-int
14
The categories of this paper are: math-ph
10
The categories of this paper are: q-bio
31
The categories of this paper are: ao-sci