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29 March 2024 |
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Article overview
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Revisiting Kunitomo's Sunspot Drawings during 1835-1836 in Japan | Masashi Fujiyama
; Hisashi Hayakawa
; Tomoya Iju
; Toshiki Kawai
; Shin Toriumi
; Kenichi Otsuji
; Katsuya Kondo
; Yusaku Watanabe
; Satoshi Nozawa
; Shinsuke Imada
; | Date: |
Thu, 7 Mar 2019 18:39:40 GMT (1818kb) | Abstract: | We revisit the sunspot drawings made by the Japanese astronomer Kunitomo
Toubei during 1835-1836 and recount the sunspot group number for each image.
There are two series of drawings, preliminary (P, containing 17 days with
observations) and summary (S, covering 156 days with observations), all made
using brush and ink. S is a compilation of drawings for the period from
February 1835, to March 1836. Presently, the P drawings are available only for
one month, September 1835; those of other periods have presumably been lost.
Another drawing (I) lets us recover the raw group count (RGC) for 25 September
1836, on which the RGC has not been registered in the existing catalogs. We
also revise the RGCs from P and S using the Zurich classification and determine
that Kunitomo’s results tend to yield smaller RGCs than those of other
contemporary observers. In addition, we find that Kunitomo’s RGCs and spot
areas have a correlation (0.71) that is not very different from the
contemporary observer Schwabe (0.82). Although Kunitomo’s spot areas are much
larger than those determined by Schwabe due to skill and instrument
limitations, Kunitomo at least captured the growing trend of the spot activity
in the early phase of the Solar Cycle 8. We also determine the solar rotation
axis to estimate the accurate position (latitude and longitude) of the sunspot
groups in Kunitomo’s drawings. | Source: | arXiv, 1903.3092 | Services: | Forum | Review | PDF | Favorites |
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