• Publications of The Korean Astronomical Society
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• v.32 no.1
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• pp.347-349
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• 2017

This paper reviews the legacy of the SPCIA Coronagraph Instrument (SCI) of which the primary scientific objective is the characterization of Jovian exoplanets by coronagraphic spectroscopy in the infrared. Studies on binary shaped pupil mask coronagraphs are described. Cryogenic active optics is discussed as another key technology. Then approaches to observing habitable zones in exoplanetary systems with a passively-cooled space infrared telescope are discussed. The SCI was dropped in a drastic change of the SPICA mission. However, its legacy is useful for space-borne infrared telescopes dedicated for use in exoplanetary science in the future, especially for studies of biomarkers.

• The Bulletin of The Korean Astronomical Society
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• v.36 no.2
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• pp.95.2-95.2
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• 2011

The most powerful technique for deducing the magnetic structure of the Sun is spectro-polarimetry. Detailed measurements of the polarization signal of the spectral lines (Stokes vector) allow us to infer the physical conditions in the solar atmosphere prevailing during the line formation. Inversion codes are the main tool to extract this information from the Stokes spectra. This study will focus on measurements of the chromospheric He I 1083.0 nm triplet and the photospheric Si I 1082.7 nm line. A spectropolarimetric data set of sunspots, obtained with the German Vacuum Tower Telescope (VTT) at the Teide observatory on Tenerife, is analyzed using an inversion technique. We will introduce the German Vacuum Tower Telescope and the inversion code HeLix, and will show data sets that are analyzed by HeLix.

• The Bulletin of The Korean Astronomical Society
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• v.39 no.1
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• pp.64-64
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• 2014

FU Orionis type object is a category of low mass pre-main sequence star which displays optical outburst caused by accreting material at rapid rates from their surrounding disks in a few months. V1057 Cyg was about 16 mag. In late 1969, however, it rapidly brightened more than 5 mag and classified as a FU Orionis type object. After the outburst the brightness began to weaken monotonously and in 1990's magnitude decreased 13.0 mag. We carried out photometric observations of V1057 Cyg in V R I bands from 2013 November 7 to 20 with the 76 cm Ritchey-Chretien telescope at Kyung Hee Astronomical Observatory (KHAO). These result can display the recent brightness change of V1057Cyg during observation period. We also discuss possibilities of using an on-campus telescope for astronomical research works.

• Journal of Astronomy and Space Sciences
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• v.4 no.1
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• pp.55-63
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• 1987

세계 제 2 차대전이 끝난 이후로부터 40여년간, 현대 관측천문학을 이끌어 온 Palomar 산의 500cm 반사망원경은 드디어 차세대망원경에게 leadership을 넘겨주게 되었다. 자금염출이 여의치 않아 그동안 부진했던 초대형망원경 건설이 드디어 boom을 일으키게 된 것이다. 가주공과대학의 10m 반사망원경이 제작 중에 있고, Ohio주립대학도 10m 쌍통반사망원경 건립을 추진 중에 있고, 일본도 7.5m 반사망원경 건립을 검토 중이다. 한국은 1.5m~2m 반사망원경 제작이 구체화되어가고 있으니, 1970년, 불과 40cm 반사경 1대만 갖고 고군분투하던 그때를 초기하면 실로 감계무량하다 아니할 수가 없다. 그러나 NASA는 또 한편, 차세대망원경으로서 Space Shuttle을 이용하여 위성망원경을 발사할 계획을 1965년에서부터 구상하여 수차에 걸친 발의·부결을 거듭한 끝에, 드디어 1977년, 미국회의 건조인준을 얻었다.

• The Bulletin of The Korean Astronomical Society
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• v.35 no.1
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• pp.41.1-41.1
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• 2010

IGRINS (the Immersion GRating Infrared Spectrograph) is a high resolution infrared spectrograph which is being developed by a collaboration of the University of Texas, the Korea Astronomy and Space Science Institute, and Kyung Hee University. The wavelength calibration unit of IGRINS will be situated between the telescope flange and IGRINS dewar. It will include Th-Ar hallow cathode lamp, optical elements, and gas absorption cell for the case that requires precise calibration (e.g., radial velocity observation). The system will also use a tungsten halogen lamp in an integrating sphere as a blackbody source for the flat-field imaging. IGRINS will be placed initially on the McDonald 2.7m Harlan J. Smith telescope and later on 4-8m class telescopes. We present an overview of the plan for the wavelength calibration sources and of the development process for the optical and mechanical design of the IGRINS calibration system.

• Journal of The Korean Astronomical Society
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• v.52 no.6
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• pp.227-233
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• 2019

We report the performance of the 13.7-meter Taeduk Radio Astronomy Observatory (TRAO) radio telescope. The telescope has been equipped with a new receiver, SEQUOIA-TRAO, a new backend system, FFT2G, and a new VxWorks operating system. The receiver system features a 16-pixel focal plane array using high-performance MMIC preamplifiers; it shows very low system noise levels, with system noise temperatures from 150 K to 450 K at frequencies from 86 to 115 GHz. With the new backend system, we can simultaneously obtain 32 spectra, each with a velocity coverage of 163 km s^-1 and a resolution of 0.04 km s^-1 at 115 GHz. The new operating system, VxWorks, has successfully handled the LMTMC-TRAO observing software. The main observing method is the on-the-fly (OTF) mapping mode; a position-switching mode is available for small-area observations. Remote observing is provided. The antenna surface has been newly adjusted using digital photogrammetry, achieving a rms surface accuracy better than 130 ㎛. The pointing uncertainty is found to be less than 5" over the entire sky. We tested the new receiver system with multi-frequency observations in OTF mode. The aperture efficiencies are 43±1%, 42±1%, 37±1%, and 33±1%, the beam efficiencies are 45±2%, 48±2%, 46±2%, and 41±2% at 86, 98, 110, and 115 GHz, respectively.

• Bulletin of the Korean Space Science Society
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• 2004.10b
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• pp.57-57
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• 2004

• Bulletin of the Korean Space Science Society
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• 2009.04a
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• pp.64.4-65
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• 2009

• Journal of Space Technology and Applications
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• v.4 no.3
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• pp.185-198
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• 2024

Korea Astronomy and Space science Institute (KASI) partnered with the Australian National University (ANU) to develop the adaptive optics (AO) system at the Geochang observatory with a 100 cm optical telescope for multiple applications, including space geodesy, space situational awareness and Korean space missions. The AO system is designed to get high resolution images of space objects with lower magnitude than 10 by using themselves as a natural guide star, and achieve a Strehl ratio larger than 20% in the environment of good seeing with a fried parameter of 12-15 cm. It will provide the imaging of space objects up to 1,000 km as well as its information including size, shape and orientation to improve its orbit prediction precision for collision avoidance between active satellites and space debris. In this paper, we address not only the design of AO system, but also analyze the images of stellar objects. It is also demonstrated that the AO System is achievable to a near diffraction limited full width at half maximum (FWHM) by analyzing stellar images.

• Journal of The Korean Astronomical Society
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• v.44 no.3
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• pp.81-87
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• 2011

We carry out 100-GHz band test observations with the newly-constructed KVN 21-m radio telescopes in order to evaluate their performance. The three telescopes have similar performance parameters. The pointing accuracies are about 4" rms for the entire sky. The main beam sizes are about 30" (FWHMs), which is nearly the diffraction limit of the telescopes at the observing frequency (97 GHz). The measured aperture and main-beam efficiencies are about 52% and 46%, respectively, for all three telescopes. The estimated moon efficiency is ~84% for the KVN Tamna telescope. The first sidelobes appear 50" (~1.6${\times}$FWHM) from the main beam centers and the levels are on average -14 dB.