Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Multi-wavelength Observations of the Flaring Gamma-ray Blazar 3C 66A in
  2008 October   The BL Lacertae object 3C 66A was detected in a flaring state by the Fermi
Large Area Telescope (LAT) and VERITAS in 2008 October. In addition to these
gamma-ray observations, F-GAMMA, GASP-WEBT, PAIRITEL, MDM, ATOM, Swift, and
Chandra provided radio to X-ray coverage. The available light curves show
variability and, in particular, correlated flares are observed in the optical
and Fermi-LAT gamma-ray band. The resulting spectral energy distribution can be
well fit using standard leptonic models with and without an external radiation
field for inverse-Compton scattering. It is found, however, that only the model
with an external radiation field can accommodate the intra-night variability
observed at optical wavelengths.

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The categories of this paper are: cond-mat
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The categories of this paper are: bayes-an
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The categories of this paper are: comp-gas
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The categories of this paper are: dg-ga
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The categories of this paper are: nlin
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The categories of this paper are: physics
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The categories of this paper are: q-alg
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The categories of this paper are: patt-sol
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The categories of this paper are: alg-geom
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The categories of this paper are: adap-org
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The categories of this paper are: hep-th
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The categories of this paper are: chem-ph
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The categories of this paper are: cs
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The categories of this paper are: gr-qc
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The categories of this paper are: nucl-ex
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The categories of this paper are: hep-lat