Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Development of a Speckle Interferometer and the Measurement of Fried's
  Parameter (r$_o$) at the Telescope Site   A new optical speckle interferometer for use at the 2.34 meter Vainu Bappu
Telescope (VBT), at Vainu Bappu Observatory (VBO), Kavalur, India, has been
designed and developed. Provisions have been made for observation both at the
prime focus (f/3.25), as well as at the Cassegrain focus (f/13) of the said
telescope. The technical details of this sensitive instrument and the design
features are described. An interface between the telescope and the
afore-mentioned interferometer is made based on a concept of eliminating the
formation of eddies due to the hot air entrapment. The performances of this
instrument has been tested both at the laboratory, as well as at the Cassegrain
end of the telescope. It is being used routinely to observe the speckle-grams
of close-binary (separation $<$1 arc second) stars. The size of the Fried's
parameter, r$_{o}$, is also measured.

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The categories of this paper are: q-fin
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The categories of this paper are: solv-int
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The categories of this paper are: funct-an
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The categories of this paper are: comp-gas
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The categories of this paper are: adap-org
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The categories of this paper are: atom-ph
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The categories of this paper are: dg-ga
5
The categories of this paper are: gr-qc
0
The categories of this paper are: hep-ph
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The categories of this paper are: mtrl-th
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The categories of this paper are: patt-sol
31
The categories of this paper are: ao-sci
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The categories of this paper are: chem-ph
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The categories of this paper are: alg-geom
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The categories of this paper are: acc-phys
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The categories of this paper are: nucl-ex