Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Radar Observations and the Shape of Near-Earth Asteroid 2008 EV5   We observed the near-Earth asteroid 2008 EV5 with the Arecibo and Goldstone
planetary radars and the Very Long Baseline Array during December 2008. EV5
rotates retrograde and its overall shape is a 400 /pm 50 m oblate spheroid. The
most prominent surface feature is a ridge parallel to the asteroid's equator
that is broken by a concavity 150 m in diameter. Otherwise the asteroid's
surface is notably smooth on decameter scales. EV5's radar and optical albedos
are consistent with either rocky or stony-iron composition. The equatorial
ridge is similar to structure seen on the rubble-pile near-Earth asteroid
(66391) 1999 KW4 and is consistent with YORP spin-up reconfiguring the asteroid
in the past. We interpret the concavity as an impact crater. Shaking during the
impact and later regolith redistribution may have erased smaller features,
explaining the general lack of decameter-scale surface structure.

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The categories of this paper are: atom-ph
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The categories of this paper are: ao-sci
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The categories of this paper are: adap-org
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The categories of this paper are: funct-an
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The categories of this paper are: dg-ga
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The categories of this paper are: bayes-an
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The categories of this paper are: plasm-ph
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The categories of this paper are: math-ph
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The categories of this paper are: gr-qc
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The categories of this paper are: hep-ph
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The categories of this paper are: hep-th
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The categories of this paper are: cond-mat
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The categories of this paper are: nlin
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The categories of this paper are: supr-con
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The categories of this paper are: nucl-th
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The categories of this paper are: econ