• Journal of The Korean Astronomical Society
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• v.29 no.spc1
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• pp.411-412
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• 1996

We present the update information on the International Radio Astronomy Observatory Suffa project and describe the original design of new 70-m radiotelescope RT-70 for millimeter astronomy as well. Some oreographic, seeing and climatic features of Suffa are also given.

• Journal of The Korean Astronomical Society
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• v.29 no.spc1
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• pp.409-410
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• 1996

Speckle Interferometer equipped with an ITT intensified CCD have been used on the NCUO ( National Central University Observatory, Taiwan) 24-inch telescope for studying the orbits of bright binary systems selected from the Yale's Bright Star Catalogue. The high resolution and high sensitivity ITT intensified solid state video camera ( F4577 ) has external gain and gate control functions which will simplify the design of the speckle camera and allow us to do precise speckle photometry. The goal of this project is trying to study the bright binary systems with separations between the average size of seeing disk and the diffraction limit of the 24-inch telescope. Recently some observing data have been reduced and compared with the other teams' results. We are now improving the data reduction technology and trying to use real time observing mode on the monthly routine observation.

• The Bulletin of The Korean Astronomical Society
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• v.43 no.2
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• pp.56.1-56.1
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• 2018

Astronomy education and research can benefit from a high performance telescope that is easily accessible in campus. Such a facility allows hands-on education of observations, small research projects, test of new instruments, and time-domian study of astronomical phenomena. Recently, SNU reconstructed a 40-year old observatory (also known as 구천문대), and established the new SNU Astronomical Observatory (SAO) on that site. On 2018 March 27, the 1-m optical telescope was successfully installed at SAO. Since then, this telescope has been producing wonderful images, with the best seeing value recorded being as small as 0.85 arcsec. This poster will give an overview of the 1-m telescope, and its performance based on test observations during the 2018A semester.

• The Bulletin of The Korean Astronomical Society
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• v.43 no.1
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• pp.69.2-69.2
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• 2018

On 2018 March 27, a 1-m telescope was installed at the SNU Astronomical Observatory (SAO) which is a newly constructed building at the site where the previous Kwanak Observatory (Old observatory; 구천문대) stood. A series of test observations have been performed on this telescope, and we report the first results from the test observations in this poster. In particular, we present seeing values, limiting magnitudes and sample images taken with a $4k{\times}4k$ CCD camera ($21^{\prime}{\times}21^{\prime}$).

• Publications of The Korean Astronomical Society
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• v.30 no.2
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• pp.223-224
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• 2015

We present the results of visual double stars speckle observations from 2013 using a Zeiss Double Refractor 60 cm with visual focal length f = 1,078 cm, and CCD SBIG ST-402 MEA. A Bessel V filter with ${\lambda}=550nm$ was placed in front of the CCD camera to reduce the chromatic aberration of the objective lens. The objects selected for this observation were calibration candidates and program stars with separations ranging from 0.9-6 arc second, and were located in both the northern and southern hemispheres. Seeing at Bosscha Observatory is generally 1-2 arc second, imposing a limit on visual double star separation below which the system cannot be resolved by long exposure imaging (longer than ~50 ms). Speckle interferometry methods are used to resolve double stars with separations below the typical size of seeing effects. A series of images were captured in fast short-time exposures (~50 ms) using a CCD camera. The result of our experiment shows that our system can be used to measure separations of 0.9 arc second (for systems with small ${\Delta}m$) and ${\Delta}m{\approx}3.7$ (for wide systems).

• Publications of The Korean Astronomical Society
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• v.19 no.1
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• pp.47-54
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• 2004

We present the detailed description on the fiber techniques adopted in the BOES: the design concepts and manufacturing of the v grooves, the procedures of the fiber polishing, adhering of the fibers to the v grooves, and the axis alignment of the fiber input and exit. The high efficiency and throughput of the BOES imply that the adopted fiber arts and the other optical components were well designed and properly treated. We learned that the relatively low efficiency of the 80 micron fiber comparing with the 200 and 300 micron fibers comes from the seeing and the guiding effects not from the poor fiber handling.

• Journal of The Korean Astronomical Society
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• v.38 no.2
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• pp.307-310
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• 2005

The Solar-B is the third Japanese spacecraft dedicated for solar physics to be launched in summer of 2006. The spacecraft carries a coordinated set of optical, EUV and X-ray instruments that will allow a systematic study of the interaction between the Sun's magnetic field and its high temperature, ionized atmosphere. The Solar Optical Telescope (SOT) consists of a 50cm aperture diffraction limited Gregorian telescope and a focal plane package, and provides quantitative measurements of full vector magnetic fields at the photosphere with spatial resolution of 0.2-0.3 arcsec in a condition free from terrestrial atmospheric seeing. The X-ray telescope (XRT) images the high temperature (0.5 to 10 MK) corona with improved spatial resolution of approximately 1 arcsec. The Extreme Ultraviolet Imaging Spectrometer (EIS) aims to determine velocity fields and other plasma parameters in the corona and the transition region. The Solar-B telescopes, as a whole, will enable us to explore the origins of the outer solar atmosphere, the corona, and the coupling between the fine magnetic structure at the photosphere and the dynamic processes occurring in the corona. The mission instruments (SOT/EIS/XRT) are joint effort of Japan (JAXA/NAO), the United States (NASA), and the United Kingdom (PPARC). An overview of the spacecraft and its mission instruments are presented.

• The Bulletin of The Korean Astronomical Society
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• v.40 no.1
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• pp.86.4-87
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• 2015

We will soon complete the installation of 1m telescope at Deokheung Optical Astronomy Observatory (DOAO), National Youth Space Center (NYSC). Before the test observation with NYSC 1m telescope, we present the specs of the 1M telescope and observational conditions of the DOAO site, such as the seeing data at DOAO and the atmospheric extinction coefficients obtained from the observations of standard stars and stellar clusters with 120mm and 150mm refractor in 2014. Since atmospheric extinction coefficients depend on the observational instruments as well as the atmospheric conditions of the site, the improved data with NYSC 1m telescope will be obtained right after the completion of 1M telescope installation. We are planning to invite all astronomers to use 1m telescope for their sciences via regular proposal processes in this year.

• Publications of The Korean Astronomical Society
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• v.14 no.1
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• pp.47-56
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• 1999

We have improved the control and driving system of 16' reflector at Kwanak Observatory at Seoul National University, by completing encoder unit, and by developing programs for correction of errors resulting from hardware defects. The hardware defects of this telescope system are the large backlash and the nonuniform tracking and pointing. The telescope pointing accuracy for RA is improved to a few arc minutes, and that for DEC is several tens of arc minutes. The guiding error is improved to 0.7 arcsec/minute, allowing up to 3 minutes exposure for CCD imaging under typical seeing conditions at the Observatory.

• The Bulletin of The Korean Astronomical Society
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• v.39 no.2
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• pp.101.1-101.1
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• 2014

The fluctuation of VLBI visibility phase can be occurred, predominantly caused by the irregular distribution and motion of water vapor in the atmosphere at high frequencies (>1GHz). This radio-seeing effect shows up on filled-aperture telescopes as an anomalous refraction (AR). This can be shown as if the antenna pointing-offset increases, in other words the apparent displacement of radio sources from its nominal position happens. We carried out the single-dish observations on KVN sites in order to check the effect of AR from 2010 to 2014. Orion KL, U Her, and R Leo were observed with 1second sampling time at 22.235GHz and 43.122GHz simultaneously. Each source was observed with the tracking mode for 30 minutes per a source. We analyzed the structure function, power spectrum and Allan variance of the data according to a day and a night, a season and observatories. Finally, we can infer that the AR effect depends on the atmospheric environment, especially tropospheric turbulence.