• Publications of The Korean Astronomical Society
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• v.13 no.1 s.14
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• pp.209-223
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• 1998

We have investigated future large telescopes, which should represent the next generation of Korean optical and infrared telescopes. We first studied the history of the development of large telescopes in the USA, European countries, and Japan. Based on these studies, we came up suitable Korean large telescopes, which fit the current status of Korea in terms of financial situation, required technology, sciences, and manpower. We presented the potential impacts of developing large telescopes on the relevant Korean industry and Korean astronomical society. We also discussed a possibility to install large Korean telescopes at foreign sites utilizing highly competitive seeings and twice available observing dates there.

• Journal of Astronomy and Space Sciences
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• v.40 no.1
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• pp.19-27
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• 2023

We present the results of using small telescopes in the United Arab Emirates (UAE) for observing variable stars and asteroids. Two telescopes, namely, 5" apochromatic refractor and 14" Schmidt-Cassegrain, at Al-Khatim Observatory (M44) were used for the observations. The targets were the three variable stars RR GEM, AG LMi, and DL CMi and the asteroid 22 Kalliope. We found a good consistency between our light curves and published ones for the calibration targets, i.e., the asteroid 22 Kalliope and the variable star RR GEM. According to previous studies, AG LMi has two suggested periods, 16.3 hours and 32.62 hours. Our results clearly confirm the second one, with a period of 32.6175 hours. The star DL CMi has several suggested periods as per previous studies, such as 4.0173 days, 1.9606 days, and 2.0086 days. Our observations confirm the first one, with a period of 4.0159 days. These results demonstrate the effectiveness of using small telescopes for observing variable stars and asteroids. This work provides some recommendations on using small telescopes for such observations.

• The Bulletin of The Korean Astronomical Society
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• v.44 no.2
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• pp.59.4-59.4
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• 2019

In this talk, we will give an overview of the small telescope network project in Korea. The small telescope network is a project in planning that would gather 0.4m-1.0m telescopes in Korea together for a common use in research and education, and the project is being led by the Optical/IR Astronomy Division of KAS. Even in the era of giant telescopes, small telescopes are still competitive for various research topics that require rapid response or long-term, steady monitoring. There are quite a few small telescopes in Korea, but the research use of these telescope has been very limited. By organizing these telescopes together, the small telescope network hopes to bring these telescopes in full operation and offer Korean astronomers competitive observational resources. In this talk, we will outline the project, describe potential resources, and several science cases such as multi-messenger astronomy, supernovae, and AGN. We will also introduce how this project might be run, with the expected operation of the small network starting at 2020.

• 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.

• The Bulletin of The Korean Astronomical Society
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• v.36 no.2
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• pp.87.1-87.1
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• 2011

Since early 90's, the solar X-ray telescopes such as Yohkoh SXT and Hinode XRT have observed coronal magnetic structures on the Sun's surface in the range of about $40'{\times}40'$ field-of-view (FOV) covering the full solar disk. Thus it has been stressed by the scientists that the optical structure of solar telescopes should be designed with care for improving the uniformity over a wide FOV. There would be, however, no unique solution in designing the optical system of a telescope for overcoming perfectly the problem of off-axis response variation. As a consequence, the correction of optical imperfectness of telescopes has become an important calibration step that should be performed beforehand when the observed images are to be used for photometric purposes. In particular, a special care should be taken when performing the temperature analysis with thin and thick filters for flaring activities observed at the periphery of the full FOV. From the analyses of both pre-launch calibration and in-flight observation data, the optical characteristics for describing the performance of solar X-ray telescopes, especially in view of their energy dependence, will be introduced and discussed in our presentation.

• Publications of The Korean Astronomical Society
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• v.25 no.4
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• pp.107-112
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• 2010

By joining the Giant Magellan Telescope (GMT) project, Korean astronomers will get 10% of the GMT time, starting in the late 2010s. To prepare the GMT era, it is important to evaluate the current observational research activities. We surveyed the research programs performed by domestic astronomers during 2007A - 2010A period, using optical/near - IR telescopes with a medium to large aperture mirror (larger than 4 m). We describe the method and criteria of the survey, and present the results of the analysis based on the collected data.

• Publications of The Korean Astronomical Society
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• v.30 no.2
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• pp.659-661
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• 2015

The Long Baseline Array is an array of radio telescopes using the technique of Very Long Baseline Interferometry to achieve milli-arcsecond-scale angular resolution. The core telescopes are located in Australia, with telescopes in New Zealand and South Africa also participating regularly. In this paper the capabilities of the Long Baseline Array are described, and examples of the science undertaken with the array are given.

• The Bulletin of The Korean Astronomical Society
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• v.46 no.1
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• pp.49.1-49.1
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• 2021

SomangNet team aims to make use of small- to medium-sized telescopes for photometric follow-up observations of transiting extrasolar planets orbiting a bright host star. Newly discovered transiting planets need frequent monitoring in order to maintain knowledge of the transit ephemeris. DOAO 1.0 m telescope and CBNUO 0.6 m telescopes are used for our monitoring. We will present some preliminary results of our observations and analysis.

• The Bulletin of The Korean Astronomical Society
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• v.36 no.1
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• pp.35.1-35.1
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• 2011

The solar X-ray telescopes, the Yohkoh SXT and the Hinode XRT, have observed for a couple of decades a variety of coronal structures in the range of wide field-of-view (FOV) covering the full solar disk. It has been emphasized that the optical structure of solar telescopes should be designed with care for improving the uniformity over the full FOV. The vignetting effect is one of the important optical characteristics for describing the performance of a telescope, which reflects the ability of collecting the incoming light at different locations and different photon energies. The correction of this vignetting effect would be an important calibration step that should be performed in advance, especially when the observed images are to be used for photometric purposes. Since the vignetting effect of solar X-ray telescopes shows wavelength dependence, a special care should be taken when, for example, performing the temperature analyses with thin and thick filters for flaring activities observed at the periphery of the full FOV. The results of analysis of pre-launch calibration data for the evaluation of vignetting effect will be introduced in detail.

• Journal of the Optical Society of Korea
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• v.5 no.3
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• pp.70-75
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• 2001

Next Generation Space Telescope (NGST) is under design study for proposed launch around 2008. It will take over the task of Hubble Space Telescope (HST) and provide much more detailed information about celestial objects. Present large telescopes both in space and on the ground contain aspheric mirrors, called Ritchey-Chretien type. As the size of the telescope becomes larger and the optical quality is requested to be higher, reaching the diffraction limit, more accurate optical testing methods are required. However, there are few testing methods which can achieve the required accuracy for aspheric optics, and none of them has achieved it with certainty. The failure of producing the primary mirror of the Hubble Space Telescope to meet specification is a good example. Moreover, testing aspheric mirrors of large convex form adds the difficulty to extreme. In this paper, space telescopes and large ground-based telescopes are surveyed and testing methods for aspheric optics are reviewed. a method of testing aspheric convex mirrors is suggested.