Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Quasi-simultaneous five-frequency VLBA observations of PKS 0528+134   We present results of Very Long Baseline Array (VLBA) observations of PKS
0528+134 at five frequencies (2.3, 5.0, 8.4, 15.4, and 22.2 GHz). These
quasi-simultaneous data enable us to study the spectral distribution of Very
Long Baseline Interferometer (VLBI) components for the first time in this
highly variable source, from which the central compact core is identified. Our
observations indicate that there are two bendings for the jet motion at parsec
scale. We provide an approximate spatial fit to the curved jet trajectory using
the Steffen et al. (\cite{Steffen95}) helical model. We further investigate the
proper motions of three jet components, which all show superluminal motion. At
high frequencies (15.4 and 22.2 GHz) we detected a new component, which is
estimated to be related to a radio burst peaking at about 2000.

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The categories of this paper are: nucl-ex
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The categories of this paper are: plasm-ph
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The categories of this paper are: nucl-th
35
The categories of this paper are: mtrl-th
31
The categories of this paper are: ao-sci
3
The categories of this paper are: physics
34
The categories of this paper are: chem-ph
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The categories of this paper are: hep-th
1
The categories of this paper are: cs
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The categories of this paper are: nlin
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The categories of this paper are: solv-int
32
The categories of this paper are: atom-ph
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The categories of this paper are: acc-phys
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The categories of this paper are: funct-an
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The categories of this paper are: eess
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The categories of this paper are: cond-mat