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. IV. uvbyCa Observations
  of Metal-Weak Candidates from the Northern HK Survey   CCD photometry on the uvbyCa system has been obtained for 521 candidate
metal-poor stars from the northern hemisphere HK survey of Beers and
colleagues. Reddening corrections, classifications of stars by luminosity
class, and the derivation of metal abundances based on Stromgren indices m1 and
hk are described and presented, along with preliminary spectroscopic estimates
of abundance. A number of extremely metal-poor stars with [Fe/H] less than or
equal to -2.50 are identified.

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The categories of this paper are: bayes-an
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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: stat
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The categories of this paper are: adap-org
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The categories of this paper are: nucl-th
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The categories of this paper are: chao-dyn
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The categories of this paper are: physics
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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: dg-ga
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The categories of this paper are: cond-mat
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The categories of this paper are: acc-phys
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The categories of this paper are: gr-qc
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The categories of this paper are: supr-con
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The categories of this paper are: math