Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Thermal Properties and an Improved Shape Model for Near-Earth Asteroid
  (162421) 2000 ET70   We present thermal properties and an improved shape model for potentially
hazardous asteroid (162421) 2000 ET70. In addition to the radar data from 2000
ET70's apparition in 2012, our model incorporates optical lightcurves and
infrared spectra that were not included in the analysis of Naidu et al. (2013,
Icarus 226, 323-335). We confirm the general "clenched fist" appearance of the
Naidu et al. model, but compared to their model, our best-fit model is about
10% longer along its long principal axis, nearly identical along the
intermediate axis, and about 25% shorter along the short axis. We find the
asteroid's dimensions to be 2.9 km $\times$ 2.2 km $\times$ 1.5 km (with
relative uncertainties of about 10%, 15%, and 25%, respectively). With the
available data, 2000 ET70's period and pole position are degenerate with each
other. The radar and lightcurve data together constrain the pole direction to
fall along an arc that is about twenty-three degrees long and eight degrees
wide. Infrared spectra from the NASA InfraRed Telescope Facility (IRTF) provide
an additional constraint on the pole. Thermophysical modeling, using our
SHERMAN software, shows that only a subset of the pole directions, about twelve
degrees of that arc, are compatible with the infrared data. Using all of the
available data, we find that 2000 ET70 has a sidereal rotation period of 8.944
hours ($\pm$ 0.009 h) and a north pole direction of ecliptic coordinates
$(52^{\circ}, -60^{\circ}) \pm 6^{\circ}$. The infrared data, acquired over
several dates, require that the thermal properties (albedo, thermal inertia,
surface roughness) must change across the asteroid's surface. By incorporating
the detailed shape model and spin state into our thermal modeling, the multiple
ground-based observations at different viewing geometries have allowed us to
constrain the levels of the variations in the surface properties.

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The categories of this paper are: hep-ex
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The categories of this paper are: acc-phys
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The categories of this paper are: mtrl-th
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The categories of this paper are: bayes-an
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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: stat
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The categories of this paper are: hep-ph
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The categories of this paper are: physics
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The categories of this paper are: solv-int
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The categories of this paper are: quant-ph
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The categories of this paper are: chem-ph
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The categories of this paper are: q-bio
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The categories of this paper are: plasm-ph
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The categories of this paper are: comp-gas
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The categories of this paper are: hep-th