• Bulletin of the Korean Space Science Society
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• 2000.10a
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• pp.85-85
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• 2000

No Abstract, See Full Text

• Bulletin of the Korean Space Science Society
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• 2006.04a
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• pp.67-67
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• 2006

• The Bulletin of The Korean Astronomical Society
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• v.20
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• pp.13.1-13.1
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• 1995

• The Bulletin of The Korean Astronomical Society
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• v.20
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• pp.24.3-25
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• 1995

• The Bulletin of The Korean Astronomical Society
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• v.26 no.2
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• pp.50.2-50.2
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• 2001

• The Bulletin of The Korean Astronomical Society
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• v.11
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• pp.7.1-7.1
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• 1986

• Journal of Astronomy and Space Sciences
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• v.33 no.2
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• pp.127-135
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• 2016

Inactive space objects are usually rotating and tumbling as a result of internal or external forces. KOREASAT 1 has been inactive since 2005, and its drift trajectory has been monitored with the optical wide-field patrol network (OWL-Net). However, a quantitative analysis of KOREASAT 1 in regard to the attitude evolution has never been performed. Here, two optical tracking systems were used to acquire raw measurements to analyze the rotation period of two inactive satellites. During the optical campaign in 2013, KOREASAT 1 was observed by a 0.6 m class optical telescope operated by the Korea Astronomy and Space Science Institute (KASI). The rotation period of KOREASAT 1 was analyzed with the light curves from the photometry results. The rotation periods of the low Earth orbit (LEO) satellite ASTRO-H after break-up were detected by OWL-Net on April 7, 2016. We analyzed the magnitude variation of each satellite by differential photometry and made comparisons with the star catalog. The illumination effect caused by the phase angle between the Sun and the target satellite was corrected with the system tool kit (STK) and two line element (TLE) technique. Finally, we determined the rotation period of two inactive satellites on LEO and geostationary Earth orbit (GEO) with light curves from the photometry. The main rotation periods were determined to be 5.2 sec for ASTRO-H and 74 sec for KOREASAT 1.

• Journal of The Korean Astronomical Society
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• v.43 no.1
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• pp.1-8
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• 2010

JHK near-infrared photometry of star clusters in the dwarf irregular/dwarf starburst galaxy NGC 1569 are presented. After adopting several criteria to exclude other sources (foreground stars, background galaxies, etc.), 154 candidates of star clusters are identified in the near-infrared images of NGC 1569, which include very young star clusters. Especially, from analysis based on theoretical background, we found ten very young star clusters near the center of NGC 1569. The total reddening values toward these clusters are estimated to be $A_V$=1-9 mag from comparison with the theoretical estimates given by the Leitherer et al. (1999)'s star cluster model.

• Journal of Astronomy and Space Sciences
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• v.24 no.3
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• pp.209-218
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• 2007

In this paper, we have presented the observational result for the photometric quality of main telescopes in Gimhae Astronomical Observatory. Also we performed the observation of searching new minor planets as competitive work in public observatories. The observation was carried out using 60cm telescope of Gimhae Astronomical Observatory on 2007 January 13. And, $Sch\ddot{u}ler$ BVI filters and 1K CCD camera (AP8p) were used. To define the quality of CCD photometry, we observed the region of well-known standard stars in the open cluster M67. From observed data, The transformation coefficients and airmass coefficients were obtained, and the accuracy of CCD photometry was investigated. From PSF photometry, we obtained the color-magnitude diagram of M67, and considered the useful magnitude limit and the physical properties of M67. This method can be successfully used to confirm the photometric quality of main telescope in public observatories. To investigate the detection possibility of unknown object as astroid, we observed the near area of the opposition in the ecliptic plane. And we discussed the result. Our result show that it can be possible to detect minor planets in solar system brighter than $V{\sim}18.3mag$. and it can carry out photometric study brighter than V 16mag. in Gimhae Astronomical Observatory. These results imply that the public observatories can make the research work.

• Journal of the Korean earth science society
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• v.27 no.6
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• pp.670-676
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• 2006

We present a B and V band time-series CCD photometry of ${\delta}$ Scuti type variable star HR 2707. The observation was carried out for 45 nights between November 13, 2001 and February 20, 2002 with a 40 cm telescope equipped with a 1K CCD camera at the Korea National University of Education Optical Astronomy Observatory. Through the time-series CCD photometry we obtained 3011 V band and 6562 B band CCD frames. In some of these data, the V band data obtained for seven nights in January of 2002, had been used as a part of a multi-site campaign by Lopez de Coca et al. (2003). To detect pulsational frequencies, we used Discrete Fourier Transformation (DFT) and linear least square method. We have detected eight resonable pulsational frequencies and compare to previous studies we determine $f_1,\;f_2,\;f_3,\;f_4,\;f_5$ of Lopez do Coca et al. (2003) and $f_4$ for derived from this study are real pulsational frequencies of HR 2707.