• 천문학회보
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• 제35권2호
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• pp.62.2-62.2
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• 2010

The CQUEAN (Camera for QUasars in EArly uNiverse) is an optical CCD camera optimized for the observation of high redshift QSOs to understand the nature of early universe. The focal reducer, which is composed of four spherical lens, is allowed to secure a wider field of view for CQUEAN, by reducing the focal length of the system by one third. We designed the lens configuration, the lens barrel, and the adapters to assemble to attach focal reducer to the CCD camera system. We performed tolerance analysis using ZEMAX. The manufacturing of the focal reducer system and its lab test of optical performance were already finished. It turned out that the performance can meet the original requirement, with the aberration and alignment error taken into account. We successfully attached the focal reducer and CQUEAN to the cassegrain focus of 2.1m telescope at McDonald Observatory, USA, and several tests of CQUEAN system were carried out. In this presentation, I will show the process of focal reducer fabrication and the result of performance test.

• 천문학회보
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• 제35권2호
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• pp.62.1-62.1
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• 2010

CQUEAN (Camera for QUasars in EArly uNiverse) is an optical CCD camera system that consists of a science CCD camera, a guide CCD camera, and seven filters. In addition, a focal reducer is installed in front of the science camera to secure a larger field of view for the system. Engineering run of the system was carried out from Aug. 10, 2010 to Aug. 17, 2010, with 2.1m Otto Struve telescope at McDonald Observatory, USA, from which we investigated the characteristics and performance of the system. Bias and dark images were taken under various temperature conditions to examine the system behavior, and both twilight and dome flat images were obtained to investigate the appropriate preprocessing procedures of the data. Crude initial estimate indicated one hour integration would reach limiting magnitude of 24.2 in i-band with S/N ratio of 5, with CQUEAN at 2.1m telescope. The detailed results of the engineering run will be presented.

• 천문학회보
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• 제42권1호
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• pp.54.2-54.2
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• 2017

We present the results of high-resolution optical (R ~ 30,000) and near-infrared (R ~ 45,000) spectroscopic monitoring observations of a new FU Orionis-like young stellar object, 2MASS J06593158-0405277. FU Orionis objects (FUors) are well-studied examples of episodic accretion because of their outburst phenomenon. Recently, 2MASS J06593158-0405277 exhibited an outburst and was identified as an FUor. It provides an important opportunity to investigate the whole FUors phenomenon from its pre-outburst to its post-outburst phase. We observed 2MASS J06593158-0405277 with the Bohyunsan Optical Echelle Spectrograph (BOES) of the Bohyunsan Optical Astronomy Observatory (BOAO) and the Immersion GRating INfrared Spectrograph (IGRINS) of Harlan J. Smith Telescope (HJST) at the McDonald observatory since December 24, 2014. We detected a number of lines and present here our analysis for time variations of those spectral lines.

• 천문학회보
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• 제43권1호
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• pp.68.2-68.2
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• 2018

Spectroscopic observations commonly use a slit or fiber; however, non-slit spectroscopy enables us to observe a larger number of targets in one frame of image. Hence, it has been adopted as an observational mode for observatories like HST and JWST. Slitless spectroscopy requires wavelength calibration solutions in order to distinguish and measure the absorption / emission lines from the spectra with high accuracy. We installed the Volume Phase Holographic (VPH) grating to SQUEAN camera on the McDonald 2.1m telescope and obtained images with spectral resolutions of ~ 100 and 200. In order to derive the wavelength calibration, we measured the distances between the 0th order images and spectral features of various quasars. The distances are converted to wavelengths using the known wavelengths of the emission lines. We tested several different methods of spectral extraction and peak estimation of emission lines. We will present the results for the wavelength calibration and suggest the reliable methods to find the solution.

• 천문학회보
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• 제43권1호
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• pp.59.1-59.1
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• 2018

On 2018 February 5 a gamma ray burst with trigger time 04:25:29.3 UT was detected by Swift BAT and this event was named GRB 180205A. We observed the optical afterglow of GRB 180205A starting from about 1 hour after the burst until February 22 in the optical bands with the 1m telescope of Deokheung Optical Astronomy Observatory (DOAO), the 1m telescope at Mt. Lemmon Optical Astronomy Observatory(LOAO) and the 0.8m and 0.25m telescopes at McDonald Observatory. According to the fireball model, which is a well-accepted and conventional model for the afterglow of the GRB, the mechanism of the afterglow is that the expanding external blast wave of the GRB successively collides with the ambient medium and loses its energy, and as a result emits radiation at wavelengths longer than gamma rays. Here we present optical photometry and light curve of the afterglow in the R band and analyze it to characterize GRB 180205A.

• Ocean and Polar Research
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• 제24권3호
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• pp.237-247
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• 2002

We report all sky camera and Fabry-Perot interferometer (FPI) observations of mesospheric gravity waves and a 12-hour wave at Resolute $(75^{\circ}N)$ and a joint observation of 10-hour wave with Eureka $(80^{\circ}N)$. All sky camera observations showed a low occurrence of mesosphere gravity waves during equinoxes, which is similar to the mid-latitude region. A slightly higher occurrence near solstice appears to indicate that gravity waves are not filtered out by the neutral wind in the winter. The FPI observation of a 12-hour wave showed amplitude variations from day to day. The phase of the wave is mostly stable and consistent with the GSWM prediction in the winter. The phase shifts with season as predicted by the GSWM. Four events of the 12-hour wave were found in spring with amplitudes larger than the GSW predictions. The FPls at Resolute and Eureka also observed a wave with period close to 10 hours. The 10-hour wave maybe the result of the non-linear interaction between the semi-diurnal tide and the quasi-two day wave. Further studies are under way. Overall, the combined Resolute and Eureka observation have revealed some new fractures about the mesospheric gravity wave, tidal wave, and other oscillations.

• 천문학회보
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• 제36권2호
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• pp.68.1-68.1
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• 2011

Type Ia 초신성을 이용한 거리측정은 암흑에너지의 존재를 암시하는 가장 직접적인 증거를 제시하며, 이것은 Type Ia 초신성의 밝기가 표준화된 광도에서 모두 같다고 하는 가정하에서 성립한다. 하지만 최근 표준화된 Type Ia 초신성의 광도가 모은하의 특성과 상관관계가 있음을 보이는 연구결과들이 등장하여 이러한 가정에 대한 의문이 제기되었다. Gallagher et al. (2008)은 조기형 모은하의 나이와 중원소 함량이 Type Ia 초신성의 밝기와 갖는 상관관계에 대하여 시도하였으나, 전체 은하의 표본갯수와 나이측정, 그리고 Hubble Residual을 구하는 과정에서 오차로 인한 한계가 있었다. 우리는 Type Ia 초신성에 나타나는 광도진화효과를 확인하기 위하여 가까운 거리에 있는 Type Ia 초신성의 조기형 모은하에 대하여 CTIO 1.5m, 보현산 1.8m, LCO 2.5 m 망원경의 긴 슬릿 분광기를 이용한 분광관측을 수행하고 있다. 관측된 모은하의 분광스펙트럼으로부터 방출선에 의한 영향을 제거한 뒤, 흡수선의 세기를 이용하여 Lick/IDS indices를 측정하고 있으며 이를Yonsei Evolutionary Population Synthesis model (YEPS)과 비교하여 은하의 나이와 중원소 함량을 추정하였다. 이 결과를 이용하여 Type Ia 초신성의 Hubble Residual과 항성종족의 나이 및 중원소 함량간의 상관관계를 통하여 Type Ia 초신성의 광도진화효과에 대해 분석할 예정이다. 현재까지 조기형 모은하 20여개에 대한 분광관측을 진행하였으며, 앞으로 긴 슬릿 분광기와 McDonald 2.7m 망원경의 VIRUS-P를 이용한 모은하의 분광관측을 추가로 수행할 예정이다.

• 천문학회보
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• 제36권2호
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• pp.79-79
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• 2011

Using deep images taken at Maidanak 1.5m telescope, at McDonald 2.1m telescope and Canada-France-Hawaii Telescope, we investigated the fraction of merging galaxies in hosts of 26 AGN which are brighter than M = -22.2 mag and nearer than z = 0.2. We found that 9 to 12 of 26 AGN host galaxies show the evidence of mergers like tidal tail, shell via visual inspection. We also studied with the merging fraction of a control sample, SDSS Stripe82 galaxies. Surface brightness limit and magnitude are similar to that of the AGN sample. We found that merging fraction of the AGN sample is higher than that of normal galaxy samples. This result implies that AGN activity may be correlated with merging. We also investigated the detailed morphology of merging feature. About ~1/4 of control sample classified as a tidal and tidal+dust are shell structures. On the other hand only one of the AGN sample shows shell structures. Almost all merging AGNs show tidal tail features. From point of view that tidal tail may be at the early stage of merging, and shell may be at the late stage of mergers, this result implies that AGN may be evolved into early-type galaxies after merging.

• 천문학회보
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• 제38권1호
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• pp.73.2-73.2
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• 2013

An autoguiding system for astronomical observations should be accurate and stable for efficient data taking. IGRINS (Immersion Grating Infrared Spectrograph) is a high resolution near-IR spectrograph which is now developed by Korea Astronomy and Space Science Institute and the University of Texas. We plan to attach this instrument on the 2.7m telescope at the McDonald observatory in 2013. IGRINS consists on three detector modules, i. e., H and K band spectrograph modules and a K band slit camera module. We use the slit camera for autoguiding of the telescope. In this poster, we describe the system architecture of the hardware and software of the autoguiding system, and the algorithm which would effectively find centers of stellar images on or outside of the slit of the infrared array.

• 한국조리학회:학술대회논문집
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• 한국조리학회 2006년도 제41차 정기하계학술세미나
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• pp.115-134
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• 2006

This study was conducted during a period from July 4 to 30 to investigate the effect of restaurant environment upon customer's satisfaction and crowdedness awareness. Total 800sets of questionnaire were distributed among major food service corporations. They were 16 restaurants from McDonald, Burger King, Popeyes, KFC, Rits Carlton, Intercontinental, The Westin Chosun, Hilton, Merriot, Outback Steak House, Bennigans, VIPS, Pizza Hut Pul-hyanggi(Scent of grass), Nolboo Co.,, and Our Story, and received 50 see each to hand out to their customers. Out of total 800 sets of questionnaires, 592 sets (74.25% were retrieved and underwent a Multiple Regression Analysis. We found the following results from the study. First among each variable of restaurant environment that had a significant effect on the crowding, 'pTast service' and 'responsiveness to customer complaints' sooted a regression coefficient value 0.381 and 0.325 respectively. Second, among each restaurant environment factor that had a significant effect on crowding, 'quality of facility' sooted the highest regression coefficient value 0.423 with a standard error score 0.1074, fellowed by 'status of waiting', 'overall ambience' and 'service quality' in ascending order. Third, in the analysis of the effect of each environmental factor upon the satisfaction rate, 'status of waiting' showed the highest regression coefficient value 0.3821 with a standard error score 0.4565, followed by 'cleanliness', 'service quality' and 'conveniency', in ascending order.