Analysis of Korean astronomical records with Chinese equatorial coordinates

Lee, K.W.

doi:10.1002/asna.201111700

Cited by 4 publications

(2 citation statements)

References 17 publications

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“…Furthermore, Kiang (1972) seems to have interpreted the reference to the Taemi Enclosure to refer to the Taemi constellation. The Enclosure covers a large area in the sky and contains several constellations including the Taemi, Samtae, and Nangwi constellations (see Figure 1 of Lee 2012). As can be seen in the figure, the Korean record seems to be reasonable considering the large territory of the Taemi Enclosure.…”

Section: Halley's Comet In 1531mentioning

confidence: 86%

“…For the English translation of all Korean records on Halley's comet observations during the Joseon Dynasty, except for those from 1456 and 1910, refer to Lee (2012). Because the records in the Ilgi are more detailed in description and extensive in number than those in the Sillok, the records of the former book for the years after 1623 are given in his work.…”

Section: Joseon Dynastymentioning

confidence: 99%

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Korean Historical Records on Halley's Comet Revisited

Lee¹,

Mihn²,

Ahn³

2014

Journal of Astronomy and Space Sciences

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Section: Halley's Comet In 1531mentioning

confidence: 86%

Section: Joseon Dynastymentioning

confidence: 99%

Korean Historical Records on Halley's Comet Revisited

Lee¹,

Mihn²,

Ahn³

2014

Journal of Astronomy and Space Sciences

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Geomagnetic declination derived from the positional records of Martian retrograde motion in 1491

Ahn

2021

Publications of the Astronomical Society of Japan

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Mars exhibited retrograde motions from January 4 to March 26 in 1491 CE. The Annals of the Joseon Dynasty has more than 40 records of observations with 38 lodge angles and 4 polar angles corresponding to the equatorial coordinates measured with an observing device called a small abridged armilla, as well as 34 angular separations of Mars with respect to neighboring stars estimated by eye. Accurate positions for Mars are calculated for comparison with the records, and we find a number of interesting aspects to those observations. A length unit of chi, used for reporting angular separations, is equivalent to 1 du or a Chinese angular unit. We find that the axis of the observing device might have been misaligned with the north celestial pole (NCP), and that some court astronomers might have rounded down their measurements while other astronomers might have rounded them up. In order to correct the misalignment, we apply a χ2 minimization scheme to the lodge and polar angles simultaneously, and find that the device was misaligned with the NCP by −0.°8 ± 0.°3 in elevation and −1.°3 ± 0.°3 in azimuth if the measurements had been rounded down, while it was misaligned with the NCP by −0.°4 ± 0.°3 in elevation and −2.°2 ± 0.°3 in azimuth if the measurements had been rounded up. The axis of the device was off from the NCP and aligned with a point below and to the west of the NCP. Since a magnetic compass was used for the alignment, the misalignment angle of the polar axis in azimuth is equal to the geomagnetic declination at Seoul in 1491 CE. The misalignment angles in azimuth we have obtained are in agreement with recent geomagnetic models within the 1–2 σ uncertainties of the models. Moreover, the single measurement error characterizing the observing device is estimated to be 0.°3.

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Precision of measurements and the biases due to the geomagnetic declination in the Korean observations of the comet C/1723 T1

Ahn

2021

Publications of the Astronomical Society of Japan

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Positions of the comet C/1723 T1 recorded in Korean historical resources are analysed to estimate the precision of measurements and the bias due to the geomagnetic declination at Seoul. We calculate the ephemeris of the comet by adopting the orbital elements determined by Gustav Spörer in 1843 based upon the Bradley’s telescopic observations in 1723. We confirm that the Bradley’s observations have a measurement error of 25″. The positions of the comet recorded in the Korean manuscripts are compared with the modern ephemeris. We find that there are misalignments in the instrument’s polar axis with Earth’s rotation axis: if the measurements were rounded up, there are alignment errors of 0.°0 ± 0.°2 in elevation and $-{0{_{.}^{\circ}}3}\pm {0{_{.}^{\circ}}3}$ in azimuth (to 1σ); if the measurements were rounded down, there are alignment errors of −0.°5 ± 0.°4 in elevation and +0.°5 ± 0.°6 in azimuth (to 1σ). Assuming that the instrument’s polar axis was aligned with a magnetic compass, we can regard the misalignment of the polar axis in azimuth as the geomagnetic declination at Seoul in 1723. We find that the geomagnetic declination obtained is in agreement with the recent models of the historical geomagnetic fields. We also obtain the one-time measurement error of ${0{_{.}^{\circ}}25}$, which is not different from the one-time measurement error of ${0{_{.}^{\circ}}3}$ obtained from the observational data of Mars in 1491.

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Analysis of Korean astronomical records with Chinese equatorial coordinates

Cited by 4 publications

References 17 publications

Korean Historical Records on Halley's Comet Revisited

Korean Historical Records on Halley's Comet Revisited

Geomagnetic declination derived from the positional records of Martian retrograde motion in 1491

Precision of measurements and the biases due to the geomagnetic declination in the Korean observations of the comet C/1723 T1

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