Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Swift observations of SAX J1808.4-3658: monitoring the return to
  quiescence   The transient accreting millisecond pulsar SAX J1808.4-3658 has shown several
outbursts to date but the transition from outburst to quiescence has never been
investigated in detail. Thanks to the Swift observing flexibility, we monitored
for the first time the decay to quiescence during the 2005 outburst. At
variance with other transients, wide luminosity variations are observed. In
addition, close to quiescence, SAX J1808.4-3658 seems to switch between two
different states. We interpret them in terms of the accretion states accessible
to a magnetized, fast rotating neutron star.

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The categories of this paper are: mtrl-th
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The categories of this paper are: comp-gas
4
The categories of this paper are: cond-mat
7
The categories of this paper are: hep-th
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The categories of this paper are: hep-ex
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The categories of this paper are: ao-sci
1
The categories of this paper are: cs
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The categories of this paper are: nlin
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The categories of this paper are: alg-geom
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The categories of this paper are: nucl-th
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The categories of this paper are: math
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The categories of this paper are: solv-int
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The categories of this paper are: plasm-ph
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The categories of this paper are: gr-qc
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The categories of this paper are: adap-org
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The categories of this paper are: funct-an