Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Multi-epoch VLBA observations of 3C 66A   We present the results of six-epoch Very Long Baseline Array (VLBA)
observations of 3C~66A. The high-resolution Very Long Baseline Interferometer
(VLBI) maps obtained at multi-frequency (2.3, 8.4, and 22.2 GHz) simultaneously
enabled us to identify the brightest compact component with the core. We find
that the spectrum of the core can be reasonably fitted by the synchrotron
self-absorption model. Our VLBA maps show that the jet of 3C~66A has two
bendings at about 1.2 and 4 mas from the core. We also give possible
identifications of our jet components with the components in previous VLBA
observations by analysing their proper motions. We find consistent differences
of the position from the core in one component between different frequencies at
six epochs.

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The categories of this paper are: ao-sci
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The categories of this paper are: econ
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The categories of this paper are: supr-con
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The categories of this paper are: chem-ph
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The categories of this paper are: solv-int
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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: comp-gas
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The categories of this paper are: physics
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The categories of this paper are: eess
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The categories of this paper are: chao-dyn
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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: q-bio
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The categories of this paper are: hep-ex
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The categories of this paper are: cs