• 천문학회보
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• 제40권2호
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• pp.43.1-43.1
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• 2015

After successful commissioning observations in 2014, Immersion Grating Infrared Spectrograph (IGRINS) has been conducting its normal scientific operations on the 2.7m Harlan J. Smith telescope at the McDonald Observatory and has been producing high spectral resolution near-infrared spectroscopic data in excellent quality. We will present the current status of the instrument and its software packages, and highlight initial scientific results. In particular, we will discuss possibilities of having IGRINS on larger telescopes.

• 천문학회보
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• 제38권2호
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• pp.67.1-67.1
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• 2013

It has been known that HCN is one of ubiquitous high-density gas tracer, and the abundance ratio between HCN and its Isomer, HNC sensitively depends on kinetic temperature in star-forming regions. Here we investigate the molecular abundance ratio toward three different evolutionary phases of massive star formation: Infrared Dark Clouds, High-mass Protostellar Objects and Ultracompact HII Regions. We obtained the abundances of HCN and HNC using optically thin H13CN and HN13C lines observed with the KVN single-dish telescopes and MAMBO 1.2mm and SCUBA $850{\mu}m$ continuum data. According to our results, the ratio of [HCN]/[HNC] increases statistically with the evolutionary stage, indicative of the effect of temperature. We also found a strong anti-correlation between the column density of molecular hydrogen and the HNC abundance.

• Journal of Astronomy and Space Sciences
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• 제29권1호
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• pp.85-91
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• 2012

Optical interferometry and polarimetry have separately provided new insights into stellar astronomy, especially in the fields of fundamental parameters and atmospheric models. We present: scientific justifications for "full-Stokes" optical interferometric polarimetry (OIP); updated instrument requirements; preliminary beam combiner designs; polarimeter design; end-to-end OIP data reduction; and realistic reimaged full-Stokes models of Be stars with a suitable number of telescopes plus noise sources. All of this work represents preliminary research to construct an OIP beam combiner.

• 천문학회보
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• 제39권2호
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• pp.120.2-120.2
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• 2014

본 연구에서는 2011년에 설립된 부산과학고등학교 별샘천문대에 있는 32인치 반사망원경을 비롯한 여러 천체망원경들을 간단히 소개하고 관측을 통해 성능을 분석하여 향후 교육과 연구에 활용할 수 있는 기초 자료를 제공하고자 한다. 관측기기들의 기계적인 특성을 분석하기 위해 가대의 추적 특성과 정밀도, 지향특성 등을 조사한다. BVI 표준성 관측을 통한 표준계 변환 결과를 제시하고, 한계등급에 대해 고찰한다. 이를 통해 32인치 주망원경과 기타 보조 망원경 및 교육용 기자재를 활용하여 관측할 수 있는 주제를 모색하고 그 한계를 제시한다.

• 천문학회보
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• 제39권2호
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• pp.64.1-64.1
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• 2014

We study the dust and star-formation characteristics of a nearby dwarf elliptical galaxy, NGC 855. With various archival data from ultraviolet to far-infrared, we build up the spectral energy distribution (SED) that can give us constraints on stellar populations, dust characteristics, star-formation history, etc. From GALEX and SDSS data, slightly de-centered bluer central core is confirmed, where star formation might take place. This regions is coincident with seemingly dis-integrated cores detected by Spitzer IRAC data and with bright Ha feature observed at ground-based telescope. The PACS and SPIRE data by Herschel Space Observatory show the dominant dust features at the center. Lastly, we propose necessary follow-up observations with ground-based telescopes to investigate spectral properties of NGC 855.

• 천문학회보
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• 제39권2호
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• pp.116.1-116.1
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• 2014

Korea officially joined the ALMA (Atacama Large Millimeter/submillimeter Array) project on August 17, 2014. Korea was allowed to apply for the Cycle 2 call-for-proposal before joining the project. Korea submitted 17 proposals, and 4 of them were selected as high-priority. The fund of an 11-year Korean ALMA project in the KASI (Korea Astronomy and Space Science Institute) was approved. The project team formulated an ARC (ALMA Regional Center) node at the KASI and already started its supporting activities for the Korean Astronomical Society. The team also set up a future development plan for ASTE (Atacama Submillimeter Telescope Experiment) and ALMA. A couple of engineers are now doing concept design of a multi-beam receiver system for the ASTE, Because of the ALMA participation, Korea could also access open-use time of ASTE and Mopra telescopes organized by Japan. As of this writing, EACOA (East Asia Core Observatories Association) is now under discussion on making an organization called "East Asian Observatory" and the possible operation of JCMT (James Clerk Maxwell Telescope). I will briefly mention the future prospect of these activities.

• 천문학회보
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• 제39권2호
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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.

• 천문학회보
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• 제39권2호
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• pp.79.2-79.2
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• 2014

Galactic radio pulsar population is diverse. So far about 2300 radio pulsars are known in the Milky Way, in addition to Large and Small Magellanic Clouds. Radio pulsar observations at a few hundreds MHz up to ~10 GHz have been active and they are proved to be fruitful. Low frequencies are preferred mainly because of the steep ratio spectrum of pulsars. However, developments in pulsar backends (e.g. a wide-band spectrometer) and improved system sensitivities make it possible to observe pulsars at higher frequencies using large, single-dish telescopes up to ~18 GHz. Going forward, mm-wavelength observations is expected to open a new window in pulsar astronomy. In particular, frequencies well above ~15 GHz are pre-requisite to detect pulsars in the Galactic Center where radio pulsed signals are severely scattered by interactions with the interstellar medium. Recent discoveries strongly imply that there are subsets of pulsars with an apparently flat spectrum, such as magnetars. In April 2014, the first pulsar (magnetar) was discovered only 3 arcmin from Sgr A*, PSR J1745-2900. We will present a brief overview on pulsar populations focusing on those observable at high frequencies. We will also discuss prospects of pulsar observations in mm-wavelengths and how we can utilize the Korean VLBI network.

• 천문학회보
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• 제39권2호
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• pp.40-40
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• 2014

Through KASI, Korean astronomers will have access to the Gemini Observatory starting in 2015. Gemini operates two optical/infrared 8m-class telescopes: one on the northern hemisphere in Hawaii, one on the southern hemisphere in Chile. Both are equipped with state of the art instruments and adaptive optics systems that will be presented. Gemini also offers the opportunity for instrument development and welcomes visiting instruments. In terms of operations, Gemini offers to its partners three ways of applying for time: through semester-basis calls for standard programs, through yearly calls for Large and Long Programs, and through monthly calls for fast turnaround programs. Gemini operates in queue mode (observing for the principal investigators and allowing flexibility in the time domain), as well as in the classical visitor mode (where principal investigators come to the telescope). I will explain the requirements and advantages of all these modes as well as a full update on the Gemini Observatory.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 학술대회 논문집 정보 및 제어부문
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• pp.560-562
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• 2005

The electronic transmission of VLBI data(dubbed e-VLBI) presents a special challenge to the use of high-speed global network. with long-term requirements for simultaneous or near-simultaneous Gbps data streams from antennas worldwide converging in a single processing center, e-VLBI is both a useful and highly synergetic application for global high-speed networksAs broband access to high speed research and education networks has become increasingly available to radio telescopes around the world the use of e-VLBI has also increased. High bandwidth e-VLBI experiments have been achieved across wide areas e-VLBI has also been used for the transfer of data from "production"exoeriments