Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Ten-year optical monitoring of PKS 0735+178: historical comparison,
  multiband behaviour and variability timescales   New data and results on the optical behaviour of the blazar PKS 0735+178 are
presented. In addition the whole historical light curve, and a new photometric
calibration of comparison stars are reported. Optical spectral indexes are
calculated and studied on years scales, while several methods for time-series
analysis are applied to the whole historical series and to each observing
season of our data set. This allowed to search and identify optical variability
modes, characteristic timescales and the signal power spectrum over 3 decades
in time. In the last 10 years the optical flux of PKS 0735+178 exhibited a
rather achromatic long-term behaviour and a variability mode resembling the
shot-noise. The brightness level was in an intermediate/low state with a mild
flaring activity and a superimposition/succession of rapid and slower flares,
with no extraordinary/isolated outbursts but, at any rate, characterized by 1
major active phase in 2001. Several mid-term scales (days, weeks) were found,
the more common falling into values of about 27-28 days, 50-56 days and 76-79
days. The rapid variability in the historical curve appear to be modulated by a
general, slower and rather oscillating trend, where typical timescales of about
4.5, 8.5 and 11-13 years can be identified. This spectral and temporal
analysis, accompanying our data publication, suggests the occurrence of
distinctive variability signatures at days/weeks scales, that can likely be of
transitory nature. On the other hand the possible pseudo-cyclical or
multi-component modulations at long times could be more stable, recurrent and
correlated to the bimodal radio flux behaviour and the twisted radio structure
observed by many years in this blazar.

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The categories of this paper are: alg-geom
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The categories of this paper are: plasm-ph
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The categories of this paper are: atom-ph
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The categories of this paper are: patt-sol
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The categories of this paper are: q-bio
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The categories of this paper are: q-fin
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The categories of this paper are: cond-mat
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The categories of this paper are: hep-ph
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The categories of this paper are: nucl-th
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The categories of this paper are: nucl-ex
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The categories of this paper are: cmp-lg
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The categories of this paper are: mtrl-th
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The categories of this paper are: q-alg
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The categories of this paper are: dg-ga
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The categories of this paper are: funct-an
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The categories of this paper are: solv-int