• Journal of the Optical Society of Korea
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• 제5권3호
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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.

• 항공우주기술
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• 제12권2호
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• pp.64-73
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• 2013

심우주을 더욱 효율적으로 관측하기 위해서는 지구 대기권에 천체 망원경을 탑재한 인공위성을 운용하는 것이다. 미국과 EU 등 우주 선진국에서는 허블우주망원경, 케플러 및 허셜 우주 관측 위성 등에 의해 우주 정보를 획득하여 분석하고 있다. 본 논문에서는 외국의 주요 우주 관측 위성에 대한 사양 및 현황을 고찰하고, 국내의 심우주 탐사를 위한 기술과 계획 등에 대해 기술하고자 한다.

• 한국우주과학회:학술대회논문집(한국우주과학회보)
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• 한국우주과학회 1997년도 한국우주과학회보 제6권2호
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• pp.17.1-17
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• 1997

No Abstract.See Full-text

• Journal of Astronomy and Space Sciences
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• 제4권1호
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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.

• 천문학회지
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• 제29권spc1호
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• pp.139-140
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• 1996

• 천문학회보
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• 제19권
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• pp.6.2-7
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• 1994

• 천문학회보
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• 제44권2호
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• pp.76.3-76.3
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• 2019

Intracluster stars are believed to be gravitationally bound to a galaxy cluster, however, not to individual cluster galaxies. Their presence is observed as diffuse light typically in the central region extended from the brightest cluster galaxy. The diffuse light, often referred to as intracluster light (ICL), is difficult to quantify in distant high-redshift galaxy clusters because of the significant surface brightness dimming although ICL observations in high-redshift clusters provide powerful constraints on the origin of intracluster stars. In this poster, we present ICL study of the distant galaxy cluster SPT2106-5844 at z=1.132 with Hubble Space Telescope IR imaging data. With careful control of systematics, we successfully quantify the total amount of the ICL, measure the color profile, and obtain its two-dimensional distribution. Our measurement of the high abundance of the intracluster stars in this young cluster favors the ICL formation scenario, wherein production of intracluster stars are predominantly associated with the BCG formation.

• 천문학회보
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• 제40권1호
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• pp.46.2-46.2
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• 2015

Modern methods in determining the value of the Hubble constant are divided into two main ways: the classical distance ladder method and the inverse distance ladder method. The classical distance ladder method is based on Cepheid calibrated Type Ia supernovae (SNe Ia), which are known as powerful distance indicator. The inverse distance ladder method uses cosmic microwave background radiation, which emitted from the high-z universe, and the cosmological model. Recent estimations of the Hubble constant based on these two methods show a $2{\sim}3{\sigma}$ difference, which called the "Hubble tension". It is currently an issue in the modern cosmology. We have been working on the luminosity calibration of SNe Ia based on the Tip of the Red Giant Branch (TRGB), which is a precise population I distance indicator. We present the TRGB distance estimates of 5 SNe Ia host galaxies with the archival Hubble Space Telescope image data. We derive the mean absolute maximum magnitude of 5 SNe Ia and the value of the Hubble constant. Cosmological implications of our estimate will be discussed.

• 천문학회보
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• 제44권1호
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• pp.74.1-74.1
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• 2019

We present an ongoing imaging survey of the host galaxies of hard X-ray-selected active galactic nuclei (AGNs) observed with the Hubble Space Telescope (HST). The snapshot images are taken with the Advanced Camera for Surveys through an HST gap-filler program. The sample, selected from the 70-month Swift-BAT X-ray source catalog, represents an unbiased and uniform AGN population, which will enable us to test the AGN unification model and explore the physical connection between host galaxies and central supermassive black holes. We also plan to investigate the AGN triggering mechanism by examining merger signatures and searching for dual nuclei. We present the pipeline for imaging analysis and the current status of the survey.

• Journal of Astronomy and Space Sciences
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• 제19권3호
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• pp.173-180
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• 2002

Images taken with the Chandra X-ray telescope have for the the first time revealed the central, wind-driven, hot bubble (Chu et al. 2001), while Hubble Space Telescope (HST) WFPC2 images of the Cat's Eye nebula, NGC 6543, show that the temperature of the halo region of angular radius ~ 20", is much higher than that of the inner bright H II region. With the coupling of a photoionization calculation to a hydrodynamic simulation, we predict the observed 〔O III〕 line intensities of the halo region with the same O abundance as in the core H II region: oxygen abundance gradient does not appear to exist in the NGC 6543 inner halo. An interaction between a (leaky) fast stellar wind and halo gas may cause the higher excitation temperatures in the halo region and the inner hot bubble region observed with the Chandra X-ray telescope.