Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: An extensive photometric study of the recently discovered intermediate
  polar V647 Aur (1RXS J063631.9+353537)   We report the results of photometry of the intermediate polar V647 Aur.
Observations were obtained over 42 nights in 2012 and 2013. The total duration
of the observations was 246 h. We clearly detected three oscillations with
periods of 932.9123+\-0.0011, 1008.30797+\-0.00038 and 1096.955+\-0.004 s,
which may be the white dwarf spin period and two orbital sidebands,
accordingly. The oscillation with a period of 932.9123 s has a quasi-sinusoidal
pulse profile with a slightly changeable semi-amplitude from 10.9 mmag in 2012
to 12.5 mmag in 2013. The oscillation with a period of 1008.30797 s has a
slightly asymmetric pulse profile with a remarkable small hump on the ascending
part. The semi-amplitude of this oscillation is highly changeable both in a
time-scale of days (26-77 mmag) and in a time-scale of years (47 mmag in 2012
and 34 mmag in 2013). The oscillation with a period of 1096.955 s has a highly
asymmetric pulse profile with a semi-amplitude of about 6 mmag. The three
detected oscillations imply an orbital period of 3.46565+\-0.00006 h. By
comparing our data with the data of B. T. Gansicke et al., which were obtained
8 years ago, we discovered that the spin period of the white dwarf in V647 Aur
decreases with dP/dt=(-1.36+\-0.08) X 10^-10. This important result should be
confirmed by future observations. Our oscillation ephemeredes and times of
maxima can be useful for this confirmation.

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The categories of this paper are: atom-ph
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The categories of this paper are: econ
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The categories of this paper are: nucl-ex
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The categories of this paper are: nucl-th
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The categories of this paper are: q-bio
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The categories of this paper are: chem-ph
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The categories of this paper are: stat
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The categories of this paper are: dg-ga
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The categories of this paper are: ao-sci
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The categories of this paper are: patt-sol
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The categories of this paper are: comp-gas
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The categories of this paper are: quant-ph
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The categories of this paper are: hep-ph
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The categories of this paper are: hep-lat
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The categories of this paper are: q-fin
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The categories of this paper are: cs