• Title/Summary/Keyword: telescopes

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A PRELIMINARY STUDY ON THE FUTURE LARGE KOREAN TELESCOPE (우리나라의 대형망원경 설치를 위한 사전조사연구)

  • KIM DOO HWAN;JANG MIN HWAN;KIM SANG JOON
    • 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.

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On the Optical Characteristics of Solar X-Ray Telescopes: Possible Relation between Vignetting Effect and Mirror Scattering

  • Shin, Jun-Ho;Sakurai, Takashi
    • 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.

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100-GHZ BAND TEST OBSERVATIONS OF THE KVN 21-M RADIO TELESCOPES

  • Kim, Kee-Tae;Byun, Do-Young;Je, Do-Heung;Wi, Seog-Oh;Bae, Jae-Han;Jung, Tae-Hyun;Lee, Chang-Hoon;Han, Seog-Tae;Song, Min-Gyu;Jung, Jae-Hoon;Chung, Hyun-Soo;Kim, Hyo-Ryung;Kim, Bong-Gyu
    • 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.

SURVEY ON THE OBSERVATIONAL RESEARCH ACTIVITIES USING MID-TO-LARGE SIZE TELESCOPES (중대형 망원경을 이용한 관측연구 현황)

  • Woo, Jong-Hak
    • 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.

THE LONG BASELINE ARRAY

  • EDWARDS, PHILIP G.;PHILLIPS, CHRIS
    • 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.

Observations of exoplanets with small telescopes

  • Kim, Yonggi;Kang, Wonseok;Kim, Taewoo;Hinse, Tobias C.;Yoon, Joh-Na;Kim, Haeun
    • 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.

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The Off-Axis Properties of Solar X-Ray Telescopes: I. Evaluation of the Vignetting Effect

  • Shin, Jun-Ho;Sakurai, Takashi
    • 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.

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Developing an Optical Testing Method for Space Telescopes

  • Kim, Young-Soo
    • 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.

ESTIMATED PRODUCTIVITY OF THE GIANT MAGELLAN TELESCOPE (거대 마젤란 망원경의 논문 생산성 예측)

  • Ahn, S.H.;Park, B.G.;Kim, Y.S.;Chun, M.Y.;Kim, H.I.;Sung, H.I.;Lee, D.W.;Kim, S.C.
    • Publications of The Korean Astronomical Society
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    • v.23 no.2
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    • pp.123-128
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    • 2008
  • Productivity of the Giant Magellan Telescope is estimated based on the annual number of papers produced by the currently operating large telescopes such as the telescope at the ESO La Silla observatory, CFHT, AAT, the Magellan telescopes, ESO VLT, Japanese Subaru, the Gemini telescopes, and the Keck telescopes. We find that the amount of papers produced by a large telescope is roughly proportional to the diameter of its primary mirror. With this fact, we estimate the SCI-paper productivity of the Giant Magellan Telescope by extrapolating the productivity of the above-mentioned large telescopes. Moreover, according to the paper written in 2001 by Benn and Sanchez, the amount of highly-cited papers produced by a large telescope is roughly proportional to the light-gathering power of the telescope or the square of the diameter. Hence, we survey the productivity of Nature-class papers of the large telescopes and extrapolate the relationship to estimate the productivity of the Nature-class papers by using the Giant Magellan telescope of a filled aperture 21.4 meters in diameter. We expect that Korean astronomers will be able to produce annually 60 SCI-class papers and 20 Nature-class papers with high scientific impact by using the telescope-time corresponding to the 10% share of the Giant Magellan Telescope.

Korean Small Telescope Network (소형망원경 네트워크)

  • Im, Myungshin;Kim, Yonggi;Kang, Wonseok;Lee, Chung-Uk;Lee, Heewon;Shim, Hyunjin;Sung, Hyun-Il;Ishiguro, Masateru;Kim, Seung-Lee;Kim, Taewoo;Shin, Min-Su;Yoon, Joh-Na;Woo, Jong Hak
    • 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.

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