Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A seasonal cycle and an abrupt change in the variability characteristics
  of the intraday variable source S4 0954+65   The BLLac object S4 0954+65 is one of the main targets of the Urumqi
monitoring program targeting IntraDay Variable (IDV) sources. Between August
2005 and December 2009, the source was included in 41 observing sessions,
carried out at a frequency of 4.8 GHz. The time analysis of the collected light
curves, performed by applying both a structure function analysis and a
specifically developed wavelet-based algorithm, discovered an annual cycle in
the variability timescales, suggesting that there is a fundamental contribution
by interstellar scintillation to the IDV pattern of the source. The combined
use of the two analysis methods also revealed that there was a dramatic change
in the variability characteristics of the source between February and March
2008, at the starting time of a strong outburst phase. The analysis' results
suggest that the flaring state of the source coincides with the appearance of
multiple timescales in its light curves, indicating that changes in the
structure of the relativistically moving emitting region may strongly influence
the variability observed on IDV timescales.

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The categories of this paper are: solv-int
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The categories of this paper are: bayes-an
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The categories of this paper are: q-fin
30
The categories of this paper are: q-alg
11
The categories of this paper are: hep-lat
18
The categories of this paper are: econ
20
The categories of this paper are: acc-phys
14
The categories of this paper are: math-ph
2
The categories of this paper are: math
34
The categories of this paper are: chem-ph
35
The categories of this paper are: mtrl-th
28
The categories of this paper are: alg-geom
1
The categories of this paper are: cs
27
The categories of this paper are: comp-gas
12
The categories of this paper are: nucl-th
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The categories of this paper are: nucl-ex