Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Sloan Digital Sky Survey: Technical Summary   The Sloan Digital Sky Survey (SDSS) will provide the data to support detailed
investigations of the distribution of luminous and non- luminous matter in the
Universe: a photometrically and astrometrically calibrated digital imaging
survey of pi steradians above about Galactic latitude 30 degrees in five broad
optical bands to a depth of g' about 23 magnitudes, and a spectroscopic survey
of the approximately one million brightest galaxies and 10^5 brightest quasars
found in the photometric object catalog produced by the imaging survey. This
paper summarizes the observational parameters and data products of the SDSS,
and serves as an introduction to extensive technical on-line documentation.

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The categories of this paper are: q-bio
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The categories of this paper are: nucl-ex
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The categories of this paper are: hep-ex
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The categories of this paper are: alg-geom
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The categories of this paper are: atom-ph
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The categories of this paper are: chem-ph
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The categories of this paper are: comp-gas
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The categories of this paper are: mtrl-th
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The categories of this paper are: eess
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The categories of this paper are: ao-sci
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The categories of this paper are: adap-org
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The categories of this paper are: stat
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The categories of this paper are: bayes-an
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The categories of this paper are: gr-qc
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The categories of this paper are: dg-ga
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The categories of this paper are: chao-dyn