• 천문학회보
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• 제38권2호
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• pp.92.1-92.1
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• 2013

In this study, we examined chromospheric oscillation signatures in two solar active regions, a limb active region and a sunspot with a light bridge, observed by the Fast Imaging Solar Spectrograph (FISS) of the 1.6m New Solar Telescope (NST) at Big Bear Solar Observatory. The FISS is a slit spectrograph with a fast imaging capability and can observe the solar chromosphere in $H{\alpha}$ and Ca II $8542{\AA}$ bands simultaneously with high spectral resolutions. After dark and flat correction, we compensated for image rotation at the Coude focus and made image alignment. We estimated Doppler shifts over active regions using the bisector method and investigated the temporal and spatial fluctuations of Doppler shifts for some selected cases. And we obtain the power map by using the Lomb-Scargle periodogram technique to examine the oscillation power at different features. Finally, we will discuss our results and implications.

• Journal of Astronomy and Space Sciences
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• 제25권4호
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• pp.375-382
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• 2008

On August 31, 2001, ${\sim}$ 1705 - 1718 UT, Cluster was located near the midnight magnetotail, GSE (x, y, z) ${\sim}$ (-19, - 2,2) RE, and observed fast earthward flow bursts in the vicinity of the neutral sheet. They occurred while the tail magnetic field suddenly increased. Using simultaneous measurements in the solar wind, at geosynchronous orbit, and on the ground, it is confirmed that tail magnetic field enhancement is due to an increased solar wind pressure. In the neutral sheet region, strongly enhanced earthward flow bursts perpendicular to the local magnetic field $(V_{{\perp}x})$ were observed. Auroral brightenings localized in the pre-midnight sector (${\sim}$ 2200 - 2400 MLT) occurred during the interval of the $V_{{\perp}x}$ enhancements. The $V_{{\perp}x}$ bursts started ${\sim}$ 2 minutes before the onset of auroral brightenings. Our observations suggest that the earthward flow bursts are associated with tail reconnection directly driven by a solar wind pressure impulse and that $V_{{\perp}x}$ caused localized auroral brightenings.

• Journal of Astronomy and Space Sciences
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• 제35권1호
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• pp.47-54
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• 2018

Moon mineralogy mapper ($M^3$)'s work proved that the moon is not completely dry but has some hydroxyl/water. $M^{3{\prime}}s$ data confirmed that the amount of hydroxyl on the lunar surface is inversely related to the measured signal brightness, suggesting the lunar surface is sensitive to temperature by solar insolation. We tested the effect of solar insolation on the local distribution of hydroxyl by using $M^3$ data, and we found that most craters had more hydroxyl in shade areas than in sunlit areas. This means that the local distribution of hydroxyl is absolutely influenced by the amount of sunshine. We investigated the factors affecting differences in hydroxyl; we found that the higher the latitude, the larger the difference during daytime. We also measured the pyroxene content and found that pyroxene affects the amount of hydroxyl, but it does not affect the difference in hydroxyl between sunlit and shaded areas. Therefore, we confirmed that solar insolation plays a significant role in the local distribution of hydroxyl, regardless of surface composition.

• 천문학회보
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• 제44권1호
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• pp.63.1-63.1
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• 2019

Solar system small bodies are unusual objects in astronomical survey data in that they are moving on the celestial sphere. In addition, even in a normal status, their magnitudes are changing over time, firstly because their relative positions with respect to the Sun and Earth are continually changing, secondly because they are rotating bodies with non-spherical shapes. Furthermore, some of them might exhibit unexpected activities, which could be caused by mass ejection or disintegration. Detections and observations of such activities are challenging due to their abrupt nature. Therefore, continuous monitoring observations of large number of Solar system small bodies are required to systematically obtain detailed/transient information about them. Since 2018/2019 winter, we have launched a new project using Korea Microlensing Telescope Network (KMTNet) for detecting such transient phenomena of Solar system objects. Our main goal is to monitor the magnitudes and detect sudden brightness changes. We also plan to discover interesting new objects, and monitor rotational brightness oscillations of asteroids. We intend to monitor the magnitudes of ~ 20,000 known Solar system small bodies per night, and acquire lightcurves of ~ 1,000 asteroids.

• 천문학회보
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• 제33권2호
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• pp.32.1-32.1
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• 2008

• 천문학회보
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• 제25권1호
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• pp.16-16
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• 2000

• 천문학회보
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• 제25권2호
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• pp.36-36
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• 2000

• 한국우주과학회:학술대회논문집(한국우주과학회보)
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• 한국우주과학회 2000년도 한국우주과학회보 제9권2호
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• pp.36-36
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• 2000

No Abstract, See Full Text

• 천문학회보
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• 제34권2호
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• pp.32.2-32.2
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• 2009

• 천문학회지
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• 제56권2호
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• pp.263-275
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• 2023

The Sun-Earth Lagrange point L4 is considered as one of the unique places where the solar activity and heliospheric environment can be observed in a continuous and comprehensive manner. The L4 mission affords a clear and wide-angle view of the Sun-Earth line for the study of the Sun-Earth and Sun-Moon connections from he perspective of remote-sensing observations. In-situ measurements of the solar radiation, solar wind, and heliospheric magnetic field are critical components necessary for monitoring and forecasting the radiation environment as it relates to the issue of safe human exploration of the Moon and Mars. A dust detector on the ram side of the spacecraft allows for an unprecedented detection of local dust and its interactions with the heliosphere. The purpose of the present paper is to emphasize the importance of L4 observations as well as to outline a strategy for the planned L4 mission with remote and in-situ payloads onboard a Korean spacecraft. It is expected that the Korean L4 mission can significantly contribute to improving the space weather forecasting capability by enhancing the understanding of heliosphere through comprehensive and coordinated observations of the heliosphere at multi-points with other existing or planned L1 and L5 missions.