Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A Transit of Venus Possibly Misinterpreted as an Unaided-Eye Sunspot
  Observation in China on 9 December 1874   Large sunspots can be observed with the unaided eye under suitable
atmospheric seeing conditions. Such observations are of particular value
because the frequency of their appearance provides an approximate indication of
the prevailing level of solar activity. Unaided-eye sunspot (UES) observations
can be traced back well before the start of telescopic observations of the Sun,
especially in the East Asian historical records. It is therefore important to
compare more modern, UES observations with the results of telescopic sunspot
observations, to gain a better understanding of the nature of the UES records.
A previous comparison of Chinese UES records and Greenwich photo-heliographic
results between 1874 and 1918 indicated that a few of the UES were apparently
not supported by direct photographic evidence of at least one sunspot with a
large area. This article reveals that one of the Chinese unaided-eye
observations had possibly captured the transit of Venus on 9 December 1874. The
Chinese sunspot records on this date are compared with Western sunspot
observations on the same day. It is concluded that sunspots on the solar disk
were quite small and the transit of Venus was probably misinterpreted as a
sunspot by the Chinese local scholars. This case indicates that sunspots or
comparable "obscuring" objects with an area as large as 1000 millionths of the
solar disk could easily have been seen with the unaided eye under suitable
seeing conditions. It also confirms the visibility of sunspots near the solar
limb with the unaided eye. This study provides an explanation of the apparent
discrepancy between the Chinese UES observation on 9 December 1874 and the
Western sunspot observations using telescopes, as well as a basis for further
discussion on the negative pairs in 1900 and 1911, apparently without
sufficiently large area.

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The categories of this paper are: patt-sol
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The categories of this paper are: hep-th
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The categories of this paper are: stat
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The categories of this paper are: math-ph
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The categories of this paper are: nucl-th
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The categories of this paper are: cmp-lg
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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: chem-ph
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The categories of this paper are: plasm-ph
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The categories of this paper are: q-bio
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The categories of this paper are: ao-sci
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The categories of this paper are: acc-phys
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The categories of this paper are: dg-ga
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The categories of this paper are: funct-an
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The categories of this paper are: alg-geom