Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Variability and Period Analysis for the BL Lac AO 0235+164   Variability is one of the extreme observational properties of BL Lacertae
objects. AO 0235+164 is a well studied BL Lac through the whole
electro-magnetic wavebands. In the present work, we show its optical R band
photometric observations carried out during the period of Nov, 2006 to Dec.
2012 using the Ap6E CCD camera attached to the primary focus of the $\rm 70-cm$
meniscus telescope at Abastumani Observatory, Georgia. It shows a large
variation of $\Delta R$ = 4.88 mag (14.19 - 19.07 mag) and a short time scale
of $\Delta T_v$ = 73.5 min during our monitoring period. During the period of
Dec. 2006 to Nov. 2009, we made radio observations of the source using the 25-m
radio telescope at Xinjiang Astronomical Observatory. When a discrete
correlation function (DCF) is adopted to the optical and radio observations, we
found that the optical variation leads the radio variation by 23.2$\pm$12.9
days.

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The categories of this paper are: acc-phys
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The categories of this paper are: dg-ga
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The categories of this paper are: solv-int
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The categories of this paper are: mtrl-th
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The categories of this paper are: nucl-th
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The categories of this paper are: nlin
0
The categories of this paper are: hep-ph
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The categories of this paper are: stat
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The categories of this paper are: chem-ph
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The categories of this paper are: physics
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The categories of this paper are: q-bio
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The categories of this paper are: bayes-an
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The categories of this paper are: atom-ph
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The categories of this paper are: alg-geom
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The categories of this paper are: hep-ex
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The categories of this paper are: cond-mat