Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Outstanding Pulkovo latitude observers Lidia Kostina and Natalia
  Persiyaninova   Lidia Dmitrievna Kostina and Natalia Romanovna Persiyaninova left a bright
mark in the history of the Pulkovo Observatory, as well as in the history of
the domestic and international latitude services. In the first place, they were
absolute leaders in the latitude observations with the famous zenith telescope
ZTF-135. In 1954-2001, they obtained together more than 66'000 highly accurate
latitudes, which make about 2/3 of all the observations made by 23 observers
with the ZTF-135 after the WW2. They also provided a large contribution to
investigation of the instrumental errors, methods of the data analysis,
developing of the observing programs. Their results in studies of the latitude
variations and polar motion were also highly recognized by the community.

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The categories of this paper are: plasm-ph
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The categories of this paper are: dg-ga
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The categories of this paper are: patt-sol
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The categories of this paper are: comp-gas
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The categories of this paper are: stat
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The categories of this paper are: supr-con
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The categories of this paper are: solv-int
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The categories of this paper are: alg-geom
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The categories of this paper are: quant-ph
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The categories of this paper are: nlin
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The categories of this paper are: q-alg
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The categories of this paper are: math-ph
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The categories of this paper are: cs