Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Variability of sub-mJy radio sources   We present 1.4 GHz VLA observations of the variability of radio sources in
the Lockman Hole region at the level of > 100 uJy on timescales of 17 months
and 19 days. These data indicate that the areal density of highly variable
sources at this level is < 0.005 arcmin^{-2}. We set an upper limit of 2% to
the fraction of 50 to 100uJy sources that are highly variable (> 50%). These
results imply a lower limit to the beaming angle for GRBs of 1deg, and give a
lower limit of 200 arcmin^2 to the area that can be safely searched for GRB
radio afterglows before confusion might become an issue.

31
The categories of this paper are: ao-sci
23
The categories of this paper are: solv-int
37
The categories of this paper are: supr-con
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The categories of this paper are: quant-ph
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The categories of this paper are: math-ph
5
The categories of this paper are: gr-qc
35
The categories of this paper are: mtrl-th
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The categories of this paper are: hep-ex
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The categories of this paper are: nlin
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The categories of this paper are: stat
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The categories of this paper are: chao-dyn
7
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: econ
1
The categories of this paper are: cs
24
The categories of this paper are: dg-ga