• Journal of Astronomy and Space Sciences
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• v.14 no.1
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• pp.33-43
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• 1997

New BVR CCD photometric observations of EB type close binary V388 Cyg were obtained at the Sobaeksan Astronomy Observatory during 10 nights from October to December 1995. We analyse new 3 color (B, V & R) light curves simultaneously using the Wilson-Devinney code. Now, it is not yet clear whether V388 Cyg is contact or semidetached system. Published epochs of times of minima to data were used to study the changes in period of the system, and calculated a new light elements with the secular terms, $-4.83{\times}10^{-10}$, which indicated the continuous decrease of the period.

• Publications of The Korean Astronomical Society
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• v.11 no.1
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• pp.139-146
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• 1996

Galactic open clusters NGC 1907 and NGC 1912 are known as a binary cluster candidate by Subramaniam et al.(1995). With the SNUO 0.6m telescope, UBV CCD photometric observations were performed for 62 stars in NGC 1907 within the area of $8'{\times}8'$ and 203 stars in NGC 1912 within the area of $15'{\times}15'$ area. We obtained C-M and C-C diagrams. Their mean reddenings are E(B-V) = $0.50{\pm}0.03$ for NGC 1907 and $0.27{\pm}0.03$ for NGC 1912. The distance moduli are estimated as $10.9{\pm}0.15$ and $10.4{\pm}0.10$ for NGC 1907 and NGC 1912, respectively. The ages for these clusters are $400{\pm}50Myr$ for NGC 1907 and $150{\pm}30Myr$ for NGC 1912. The distance difference of the two clusters is 300pc and the age difference is 150Myr. These results imply that the two clusters are not physically connected.

• Journal of Astronomy and Space Sciences
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• v.20 no.2
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• pp.123-132
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• 2003

We performed CCD photometric observations of the W-type contact binary AB And for 10 nights from November 1995 to December 1999 using the 61-cm reflector and BVR filters at Sobaeksan Optical Astronomy Observatory. From our observations, the seasonal light curves of AB And for 1995, 1996 and 1999 were completed and 8 new times of minimum light were determined. Newly obtained light curves show that strong light variations occurred in AB And during the past five years. We adopted the 1996 light curves as reference ones and obtained the photometric solutions of them with contact mode in the Wilson-Devinney binary code. Assuming such light variations were produced by the existence of a star spot (or star spots) in the analysis, we derived the system parameters and analyzed the 1995 and 1999 light curves by adjusting only the spot parameters. As the results, we interpreted that those light variations are produced by the simultaneous existence of a hot spot and a cool spot on the secondary. We could infer that the hot spot on the secondary is produced due to mass exchange between the components suggested by Lee (1999).

• The Bulletin of The Korean Astronomical Society
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• v.40 no.2
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• pp.41.2-41.2
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• 2015

We have performed deep wide-field CCD photometry of the young open cluster IC 1805 in the famous star forming region W4, and obtained photometric data for more than 91,000 stars in the field of IC 1805 based on observations with the 3.6m CFHT and the AZT-22 1.5m telescope at Maidanak Astronomical Observatory in Uzbekistan. The photometric data cover an area $43^{\prime}{\times}45^{\prime}$ which is far larger and far deeper than any other optical observations made for the cluster. In order to select the young stellar objects with mid-IR excess emission, we have performed mid-IR photometry of the cluster using the archival images obtained with the Spitzer Space Telescope IRAC and MIPS instruments. From a preliminary analysis of the data, we determined the reddening law ($R_V=3.02{\pm}0.05$), distance modulus ($V_0-M_V=11.9{\pm}0.2$), and the spatial distribution of members.

• Publications of The Korean Astronomical Society
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• v.20 no.1 s.24
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• pp.29-35
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• 2005

Time-series observations were carried out using a 155mm refractor and a $2k{\times}3k$ CCD camera at Bohyunsan Optical Astronomy Observatory. We found 38 new variable stars in the $2.3^{\circ}{\times}2.4^{\circ}$ region around the Cepheid variable TU Cas: 22 eclipsing binary stars, 11 ${\delta}$ Scuti type stars and an RR Lyrae star, and 4 unclassified variables.

• 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 ($21^{\prime}{\times}21^{\prime}$).

• Journal of The Korean Astronomical Society
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• v.36 no.2
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• pp.49-54
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• 2003

CCD observations in V, I and H$\alpha$ for NGC 3389 are used to present photometry of 61 HII regions. Their positions, diameters and absolute luminosities have been determined. The luminosity and size distribution functions of the HII regions in NGC 3389 are discussed.

• Journal of Satellite, Information and Communications
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• v.8 no.3
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• pp.32-40
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• 2013

The Boltwood Cloud Sensor is meteorological sensor that is used to estimate an amount of clouds in the sky. This sensor will be installed for OWL(Optical Wide-field patroL) telescope and observatory system of Korea Astronomy and Space Science. Before applying this sensor to an observatory system, we performed test observations at Chungbuk University Observatory at Jincheon, Chungbuk. During the test run, a significant correlation between air temperature difference and the number of visible stars recorded in the CCD frames has not been found. This preliminary result can be attributed to test environment of the observation and our lack of knowledge on calculation algorithm as well as the hardware system of the Boltwood Cloud Sensor.In this paper, we present the procedure and the result of the performance test employing the cloud sensor.

• Aerospace Engineering and Technology
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• v.10 no.2
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• pp.154-162
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• 2011

The KOrea Multi-Purpose Satellite-3 (KOMPSAT-3) provides 0.7 m Ground Sample Distance (GSD) panchromatic image and 2.8 m GSD multi-spectral image data for various applications. The KOMPSAT-3 system data will be applied in the field of earth observations, covering land, sea, coastal zones, and Geographic Information Systems (GIS). In order to keep the swath width of 15km at nadir view of KOMPSAT-3, CCD consist of approximately 24,020 pixels excluding 20 dark pixels at both sides and has overlap region. Because there are no CCD-line sensors with a pixel size of $7{\mu}m$, the field of view is separated into 2 parts and imaged on 2 detectors, each with 12,080 pixels. Therefore, 2 detectors have different geometric characteristic. This paper provides image simulation for geometric characteristics analysis of overlapping area of KOMPSAT-3 using KOMPSAT-2 image data.

• Journal of Astronomy and Space Sciences
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• v.32 no.1
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• pp.21-32
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• 2015

We have carried out photometric follow-up observations of bright transiting extrasolar planets using the CbNUOJ 0.6 m telescope. We have tested the possibility of obtaining high photometric precision by applying the telescope defocus technique, allowing the use of several hundred seconds in exposure time for a single measurement. We demonstrate that this technique is capable of obtaining a root-mean-square scatter of sub-millimagnitude order over several hours for a V~10 host star, typical for transiting planets detected from ground-based survey facilities. We compared our results with transit observations from a telescope operated in in-focus mode. High photometric precision was obtained due to the collection of a larger amount of photons, resulting in a higher signal compared to other random and systematic noise sources. Accurate telescope tracking is likely to further contribute to lowering systematic noise by exposing the same pixels on the CCD. Furthermore, a longer exposure time helps reduce the effect of scintillation noise which otherwise has a significant effect for small-aperture telescopes operated in in-focus mode. Finally we present the results of modelling four light-curves in which a root-mean-square scatter of 0.70 to 2.3 milli-magnitudes was achieved.