• 천문학논총
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• 제25권4호
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• pp.155-165
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• 2010

In this study, we investigate the changes in the equatorial lodge degrees and polar distance degrees of determinative stars in the ancient Chinese archives. Confirmed is the fact that the coordinate values of those determinative stars defined in B.C. 104 had been used until the 8th century but were modified by the observations of Li Chunfeng (李淳風) in the early 7th century and Yixing (一行) in 723 A.D. The results of this study are compared with those in History of Chinese Astronomical Observations of Pan Nai. By applying the results of comtemporary astrodynamical calculations, their reliability is checked, and the corrected catalogues of Shi Shi (石氏) and Yixing are provided. The positional accuracy of those observations is estimated to be one degree.

• Journal of Astronomy and Space Sciences
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• 제32권1호
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• pp.51-62
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• 2015

I investigated a method for drawing the star chart in the planisphere Cheonsang-yeolcha-bunyajido. The outline of the star chart can be constructed by considering the astronomical information given in the planisphere alone and the drawing method described in Xin-Tangshu; further the chart can be completed by using additional information on the shape and linking method of asterisms out of an inherited star chart. The circles of perpetual visibility, the equator, and the circle of perpetual invisibility are concentric, and their common center locates the Tianshu-xing, which was defined to be a pole star in the Han dynasty. The radius of the circle of perpetual visibility was modified in accordance with the latitude of Seoul, whereas the other circles were drawn for the latitude of $35^{\circ}$, which had been the reference latitude in ancient Chinese astronomy. The ecliptic was drawn as an exact circle by parallel transference of the equator circle to fix the location of the equinoxes at the positions recorded in the epitaph of the planisphere. The positions of equinoxes originated from the Han dynasty. The 365 ticks around the boundary of the circle of perpetual invisibility were possibly drawn by segmenting the circumference with an arc length instead of a chord length with the ratio of the circumference of a circle to its diameter as accurate as 3.14 presumed. The 12 equatorial sectors were drawn on the boundary of the star-chart in accordance with the beginning and ending lodge angles given in the epitaph that originated from the Han dynasty. The determinative lines for the 28 lunar lodges were drawn to intersect their determinative stars, but seven determinative stars are deviated. According to the treatises of the Tang dynasty, these anomalies were inherited from charts of the period earlier than the Tang dynasty. Thus, the star chart in Cheonsang-yeolcha-bunyajido preserves the old tradition that had existed before the present Chinese tradition reformed in approximately 700 CE. In conclusion, the star chart in Cheonsang-yeolcha-bunyajido shows the sky of the former Han dynasty with the equator modified to the latitude of Seoul.

• 천문학회보
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• 제44권2호
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• pp.61.3-61.3
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• 2019

석씨성경과 천상열차분야지도 도설에 있는 이십팔수 거성들의 좌푯값을 측정한 연도를 두 가지 방법을 써서 추정하였다. 이 두 표에 있는 좌푯값들은 자오선 관측 기기를 가지고 측정한 것으로 생각된다. 그래서 이 값들에는 기기 회전축이 어긋나서 생기는 오차와 랜덤 오차가 들어 잇다. 우리는 푸리에 방법을 받아들이고, 또한 최소자승법을 새로 고안하였다. 우리는 관측 연돗값의 분산을 구하기 위해 부트스트랩 리샘플링을 시행하였다. 그 결과, 우리는 두 성표가 모두 기원전 1세기 즉 전한 후기에 만들어졌다는 사실을 알 수 있었다. 석씨성경의 관측 연도가 천상열차분야에 들어 있는 좌푯값보다 약 15-20년 정도 앞선 것으로 보인다. 그러나 그 두 연돗값의 분산이 너무 커서 석씨성경은 기원전 77년 무렵에, 또한 천상열차분야지도의 성표는 기원전 52년에 측정된 것이라는 추정은 확인할 수 없었다. 자료 개수가 더 있거나 또는 측정 오차가 절반 정도라면 검증을 통해 결정을 할 수 있을 것이다. 이러한 점에 비추어 우리는 석씨성경에 수록되어 있는 120개의 별들의 좌표 등에 관해 논의해볼 것이다.

• 천문학회지
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• 제56권2호
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• pp.137-147
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• 2023

Shoushili was the official calendrical method promulgated in 1280 CE by the Yuan dynasty. It contains a list of the angular spans in right ascensions for the 28 lunar lodges. They are known to have been measured by Guo Shoujing with his advanced instruments with an unprecedented precision or reading error of 5'. Such precise data are useful to determine their observational epoch with an error range which is narrow enough to pinpoint on which historical occasion they were observed. Using the precise SIMBAD data based on eDR3 of GAIA and carefully identified determinative stars and considering the precession of equinoxes and proper motions, we apply linear regression methods to those data and obtain the observational epoch of 1271 ± 16 CE and the measurement error of 4.1'. We also have polar distances corresponding to declinations written in another manuscript of the Ming dynasty. Since the two data sets have similar significant digits, they were suggested to have the same origin. However, we obtain their observational epoch of 1364±5 CE and the measurement error of 5.7'. They must have been measured with different instruments and on a different occasion from the observations related to Shoushili. We review the history of the calendrical reform during the 13th century in the Yuan dynasty. We conclude that the observational epoch obtained from lodge spans in Shoushili agrees with the period of observations led by Guo Shoujing or 1276-1279 CE, which is also supported by the fact that the ecliptic lodge span values listed in Shoushili were calculated from the equatorial lodge spans.