Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A Search for Stars of Very Low Metal Abundance. V. Photoelectric UBV
  Photometry of Metal-Weak Candidates from the Northern HK Survey   We report photoelectric UBV data for 268 metal-poor candidates chosen from
the northern HK objective-prism/interference-filter survey of Beers and
colleagues. Over 40 % of the stars have been observed on more than one night,
and most have at least several sets of photometric measurements. Reddening
estimates, preliminary spectroscopic measurements of abundance, and type
classifications are reported.

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The categories of this paper are: physics
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The categories of this paper are: econ
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The categories of this paper are: acc-phys
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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: nlin
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The categories of this paper are: hep-th
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The categories of this paper are: ao-sci
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The categories of this paper are: quant-ph
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The categories of this paper are: eess
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The categories of this paper are: cond-mat
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The categories of this paper are: q-fin
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The categories of this paper are: q-bio
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The categories of this paper are: plasm-ph
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The categories of this paper are: atom-ph
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The categories of this paper are: bayes-an