Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Ultraviolet Observations of Comet 96/P Machholz at Perihelion   Ultraviolet spectra of Comet 96/P Machholz were obtained during its 2002
perihelion with the UVCS instrument aboard the SOHO satellite. Emission from H
I, C II, C III, and O I, is detected near the nucleus. The outgassing rate is
in line with the value extrapolated from rates at larger distances from the
Sun, and abundances of C and O are estimated. Reconstructed images show a
nearly spherical cloud in H I Ly$\alpha$ emission and an ion tail seen in C
III. Radiation pressure on the hydrogen atoms produces a modest distortion of
the shape of the Ly$\alpha$ cloud as seen from SOHO, and it produces Doppler
shifts up to 30 km s$^{-1}$ in the outer parts of the cloud. We estimate a
ratio of C to H$_2$O similar to what is observed in other comets, so low carbon
abundance does not account for the anomalously low C$_2$ and C$_3$ ratios to
NH$_2$ observed at optical wavelengths.

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The categories of this paper are: adap-org
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The categories of this paper are: ao-sci
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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: stat
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The categories of this paper are: solv-int
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The categories of this paper are: chem-ph
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The categories of this paper are: funct-an
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The categories of this paper are: chao-dyn
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The categories of this paper are: mtrl-th
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The categories of this paper are: hep-lat
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The categories of this paper are: supr-con
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The categories of this paper are: econ
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The categories of this paper are: physics
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The categories of this paper are: q-fin
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The categories of this paper are: plasm-ph