Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The OGLE-II event sc5_2859 : a Classical Nova outburst?   The OGLE-II event sc5_2859 was previously identified as the third longest
microlensing event ever observed. Additional photometric observations from the
EROS (Experience de Recherche d'Objets Sombres) survey and spectroscopic
observations of the candidate star are used to test the microlensing
hypothesis.The combined OGLE and EROS data provide a high quality coverage of
the light curve. The colour of the sc5_2859 event is seen to change with time.
A spectrum taken in 2003 exhibits a strong Halpha emission line. The
additionnal data show that the OGLE-II sc5_2859 event is actually a classical
nova outburst.

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The categories of this paper are: math-ph
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The categories of this paper are: q-bio
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The categories of this paper are: econ
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The categories of this paper are: q-alg
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The categories of this paper are: gr-qc
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The categories of this paper are: stat
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The categories of this paper are: hep-lat
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The categories of this paper are: math
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The categories of this paper are: bayes-an
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The categories of this paper are: physics
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The categories of this paper are: nucl-th
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The categories of this paper are: dg-ga
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The categories of this paper are: plasm-ph
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The categories of this paper are: cs
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The categories of this paper are: quant-ph
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The categories of this paper are: comp-gas