• Bulletin of the Korean Space Science Society
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• 2008.10a
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• pp.36.4-37
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• 2008

KASI is planning a large telescope project to acquire 10% share of the GMT (Giant Magellan Telescope) extremely large telescope as one of national R&D project. By participating in GMT, we expect to provide the best environment for observational astronomers in Korea and give opportunity to upgrade the current research and instrumentation level to world-leading class. In this contribution, we will report the concept of the GMT project and Korean participation plan as well as the current status of fundraising activity.

• The Bulletin of The Korean Astronomical Society
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• v.43 no.2
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• pp.59.1-59.1
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• 2018

SNe light curves have been used to understand the expansion history of the universe, and a lot of efforts have gone into understanding the overall shape of the radioactively powered light curve. However, we still have little direct observational evidence for the theorized SN progenitor systems. Recent studies suggest that the light curve of a supernova shortly after its explosion (< 1 day) contains valuable information about its progenitor system and can be used to set a limit on the progenitor size, R*. In order to catch the early light curve of SNe explosion and understand SNe progenitors, we are performing a ~8hr interval monitoring survey of nearby galaxies (d < 50 Mpc) with 1-m class telescopes around the world. Through this survey, we expect to catch the very early precursor emission as faint as R=21 mag (~0.1 Rsun for the progenitor). In this poster, we outline this project, and provide updates on IMSNG projects during 2017/2018 seasons.

• Publications of The Korean Astronomical Society
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• v.15 no.spc1
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• pp.39-60
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• 2000

We will discuss two-dimmensional spectrophotometry including long-slit spectroscopy and narrow-band imaging. The basic principles, applications, and techniques of observations and data reduction of spectroscopy and spectrophotometry for extended objects are described. This discussion will focus on practical long-slit spectroscopy using a Cassegrain spectrograph attached with 2 or 4m class telescopes and on imaging spectrophotometry using narrow-band interference filter sets. We will discuss scientific applications.

• The Bulletin of The Korean Astronomical Society
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• v.40 no.2
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• pp.35.4-36
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• 2015

Gaseous inner disks are the main controller of the final structure of planetary systems as well as the building place of planets, especially of terrestrial planets. However, the inner disk of <5AU is still difficult to be spatially resolved even at the closest star forming regions. Resolving velocity structure in the disk with high resolution infrared spectroscopic study is the best approach to study the inner disk at this moment. Here, we present the IGRINS (Immersion GRating INfrared Spectrometer) result of the Class I young stellar object, ESO Ha 279a, in the Serpens molecular cloud region. IGRINS has a resolving power of R=40,000, corresponding to the velocity resolution of 7 km/s at K-band, which is perfect to study the hot inner disk structure. We report that NaI and CO overtone emission lines are indeed good tracers of the rotating inner warm disk tracing from ~0.04 to ~7AU of this source. We also report the disk properties using other emission lines.

• The Bulletin of The Korean Astronomical Society
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• v.35 no.2
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• pp.56.2-56.2
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• 2010

The SPICA (SPace Infrared Telescope for Cosmology & Astrophysics) project is a next-generation astronomical mission optimized for mid- and far-infrared observation with a cryogenically cooled 3m-class telescope. Due to its high angular resolution and unprecedented sensitivity, SPICA will enable us to resolve many key issues in the present-day astronomy. As an international collaboration, KASI proposed the near-infrared instrument which is composed of two parts; (1) science observation with the capability of imaging and spectroscopy covering $0.7{\mu}m$ to $5{\mu}m$ (FPC-S) (2) fine guiding to stabilize and improve the attitude (FPC-G). Here, we introduce the science programs proposed for SPICA/FPC-S.

• The Bulletin of The Korean Astronomical Society
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• v.44 no.2
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• pp.45.3-45.3
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• 2019

Since the high throughput for diffuse objects and the wide-area survey even with a small telescope can be achieved in space, infrared (IR) obervations have been tried through small missions in Korea. Based upon the previous technical development for infrared spectro-photometric instrument, NISS (Near-infrared Imaging Spectrometer for Star formation history) onboard NEXTSat-1, we participated in the all-sky infrared spectro-photometric survey mission, SPHEREx. The SPEHREx (Spectro-Photometer for the History of the Universe, Epoch of Reionization, and Ices Explorer) was selected as the NASA MIDEX (Medium-class Explorer) mission (PI Institute: Caltech) in this February. As an international partner, KASI will take part in the hardware development, the operation and the science for the SPHEREx. The SPHEREx will perform the first all-sky infrared spectro-photometric survey to probe the origin of our Universe, to explore the origin and evolution of galaxies, and to explore whether planets around other stars could harbor life. For the purpose of the all-sky survey, the SPHEREx is designed to have a wide FoV of 3.5 × 11.3 deg. as well as wide spectral range from 0.75 to 5.0㎛. Here, we report the status of the SPHEREx project and the progress in the Korean participation.

• The Bulletin of The Korean Astronomical Society
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• v.45 no.1
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• pp.36.2-36.2
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• 2020

Intensive Monitoring Survey of Nearby Galaxies (IMSNG) has been managed over 6 years. It aimed to constrain the progenitor system and explosion mechanism of SNe by detection of very early signal from shock heated emission. We have conducted monitoring observation of nearby bright galaxies those were carefully selected using global network of 1-m class telescopes. More than 20 SNe have occured in our target fields. As One of result of the survey, we present light curve analysis of type Ia SN 2018kp, which was discovered in NGC 3367. Based on photometric analysis, we calculated explosion parameters and set constraints of physical conditions of this supernova. We compared the results with theoretical model progenitor systems to find out which scenario is the most fitted to SN 2018kp case. Moreover, we estimate the distance to the galaxy and look into the relation between SNe and galactic physical parameters.

• Journal of The Korean Astronomical Society
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• v.53 no.6
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• pp.161-168
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• 2020

We report the discovery of a giant exoplanet in the microlensing event OGLE-2017-BLG-1049, with a planet-host star mass ratio of q = 9.53 ± 0.39 × 10-3 and a caustic crossing feature in Korea Microlensing Telescope Network (KMTNet) observations. The caustic crossing feature yields an angular Einstein radius of θE = 0.52 ± 0.11 mas. However, the microlens parallax is not measured because the time scale of the event, tE ≃ 29 days, is too short. Thus, we perform a Bayesian analysis to estimate physical quantities of the lens system. We find that the lens system has a star with mass Mh = 0.55+0.36-0.29 M⊙ hosting a giant planet with Mp = 5.53+3.62-2.87 MJup, at a distance of DL = 5.67+1.11-1.52 kpc. The projected star-planet separation is a⊥ = 3.92+1.10-1.32 au. This means that the planet is located beyond the snow line of the host. The relative lens-source proper motion is μrel ~ 7 mas yr-1, thus the lens and source will be separated from each other within 10 years. After this, it will be possible to measure the flux of the host star with 30 meter class telescopes and to determine its mass.

• Journal of Astronomy and Space Sciences
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• v.41 no.3
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• pp.171-194
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• 2024

This study reports comprehensive observations for the G5-level geomagnetic storm that occurred from May 10 to 12, 2024, the most intense event since the 2003 Halloween storm. The storm was triggered by a series of coronal mass ejections (CMEs) originating from the merging of two active regions 13664/13668, which formed a large and complex photospheric magnetic configuration and produced X-class flares in early May 2024. Among the events, the most significant CME, driven by an X2.2 flare on May 9, caught up with and merged with a preceding slower CME associated with an X-class flare on May 8. These combined CMEs reached 1 AU simultaneously, resulting in an extreme geomagnetic storm. Geostationary satellite observations revealed changes in Earth's magnetosphere due to solar wind impacts, increased fluxes of high-energy particles, and periodic magnetic field fluctuations accompanied by particle injections. Extreme geomagnetic storms resulting from the interaction of the solar wind with the Earth's magnetosphere caused significant energy influx into Earth's upper atmosphere over the polar regions, leading to thermospheric heating and changes in the global atmospheric composition and ionosphere. As part of this global disturbance, significant disruptions were also observed in the East Asian sector, including the Korean Peninsula. Ground-based observations show strong negative storm effects in the ionosphere, which are associated with thermospheric heating and resulting in decreases in the oxygen-to-nitrogen ratio (O/N₂) in high-latitude regions. Global responses of storm-time prompt penetration electric fields were also observed from magnetometers over the East-Asian longitudinal sector. We also briefly report storm-time responses of aurora and cosmic rays using all-sky cameras and neutron monitors operated by the Korea Astronomy and Space Science Institute (KASI). The extensive observations of the G5-level storm offer crucial insights into Sun-Earth interactions during extreme space weather events and may help establish better preparation for future space weather challenges.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.2
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• pp.31.1-31.1
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• 2016

SNe light curves have been used to understand the expansion history of the universe, and a lot of efforts have gone into understanding the overall shape of the radioactively powered light curve. However, we still have little direct observational evidence for the theorized SN progenitor systems. Recent studies suggest that the light curve of a supernova shortly after its explosion (< 1 day) contains valuable information about its progenitor system and can be used to set a limit on the progenitor size, R*. In order to catch the early light curve of SNe explosion and understand SNe progenitors, we are performing a ~8hr interval monitoring survey of nearby galaxies (d < 50 Mpc) with 1-m class telescopes around the world. Through this survey, we expect to catch the very early precursor emission as faint as R=21 mag (~0.1 Rsun for the progenitor). In this talk, we outline this project, and present a few scientific highlights, such as the early light curve of SN 2015F in NGC 2442.