Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: XMM-Newton and VLT observations of the isolated neutron star 1E
  1207.4-5209   In August 2002, XMM-Newton devoted two full orbits to the observation of 1E
1207.4-5209, making this isolated neutron star the most deeply scrutinized
galactic target of the mission. Thanks to the high throughput of the EPIC
instrument, ~360,000 photons were collected from the source, allowing for a
very sensitive study of the temporal and spectral behaviour of this object. The
spectral data, both time-averaged and phase-resolved, yield one compelling
interpretation of the observed features: cyclotron absorption from one
fundamental (~0.7 keV) and three harmonics, at ~1.4, ~2.1 and ~2.8 keV.
Possible physical consequences are discussed, also on the basis of the obvious
phase variations of the features' shapes and depths. We also present deep VLT
optical data which we have used to search for a counterpart, with negative
results down to ~27.

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The categories of this paper are: econ
2
The categories of this paper are: math
8
The categories of this paper are: hep-ex
31
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: math-ph
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The categories of this paper are: alg-geom
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The categories of this paper are: chao-dyn
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The categories of this paper are: adap-org
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The categories of this paper are: acc-phys
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The categories of this paper are: patt-sol
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The categories of this paper are: solv-int
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The categories of this paper are: nlin
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The categories of this paper are: nucl-th
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The categories of this paper are: bayes-an
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The categories of this paper are: atom-ph