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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of Astronomy and Space Sciences
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Journal DOI :
The Korean Space Science Society
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Volume & Issues
Volume 27, Issue 4 - Dec 2010
Volume 27, Issue 3 - Sep 2010
Volume 27, Issue 2 - Jun 2010
Volume 27, Issue 1 - Mar 2010
Selecting the target year
A CCD Photometric Study of Close Binary V445 Cep
Oh, Kyu-Dong ; Kim, Ho-Il ; Sung, Eon-Chang ;
Journal of Astronomy and Space Sciences, volume 27, issue 2, 2010, Pages 69~74
DOI : 10.5140/JASS.2010.27.2.069
We present new BVR CCD photometric light curves for the close binary star V445 Cep. A new photometric solution and absolute physical dimensions of the system were derived by applying the Wilson-Devinney program to our observed light curves and radial velocity curves published by Pych et al. The evolutional status of V445 Cep was found to coincide with those of the general low mass ratio contact binary systems.
New Light Curve Analysis for Large Numbers of Eclipsing Binaries I. Detached and Semi-Detached Binaries
Kang, Young-Woon ;
Journal of Astronomy and Space Sciences, volume 27, issue 2, 2010, Pages 75~80
DOI : 10.5140/JASS.2010.27.2.075
Several survey observations have produced light curves of more than five thousand eclipsing binaries for last 15 years. Future missions such as the Large Synoptic Survey Telescope (LSST), the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS) and Gaia are expected to yield hundreds thousands of new variable stars and eclipsing binaries. Current methods require a week to analyze the light curves of an eclipsing binary for its physical and orbital parameters. The current methods of analyzing the light curves will be inadequate to treat the overwhelming influx of new data. Therefore we developed a new method to treat large numbers of light curves of eclipsing binaries. We tested the new method by analyzing more than one hundred light curves of the detached and semi-detached eclipsing binaries discovered in the Small Magellan Cloud and present their fitted light curves with observations.
Photometric Observations of the Contact Binary System V523 Cassiopeiae
Jeong, Jang-Hae ; Kim, Chun-Hwey ; Lee, Yong-Sam ;
Journal of Astronomy and Space Sciences, volume 27, issue 2, 2010, Pages 81~88
DOI : 10.5140/JASS.2010.27.2.081
A total of 583 observations (193 in
, 190 in
, 200 in
) for V523 Cas was made on 9 nights from September to December in 2008 using the 100 cm telescope with 2K CCD camera of the Chungbuk National University Observatory. With our data BVR light curves were constructed and 9 times of minimum light were determined. We also obtained physical parameters of the V523 Cas system by analysis of the BVR light curves using the Wilson-Devinney code.
On the Period Change of the Contact Binary GW Cephei
Kim, Chun-Hwey ; Song, Mi-Hwa ; Yoon, Joh-Na ; Jeong, Jang-Hae ; Jeoung, Taek-Soo ; Kim, Young-Jae ; Kim, Jung-Yeb ;
Journal of Astronomy and Space Sciences, volume 27, issue 2, 2010, Pages 89~96
DOI : 10.5140/JASS.2010.27.2.089
BVR CCD observations of GW Cep were made on 15 nights in November through December 2008 with a 1-m reflector at the Jincheon station of the Chungbuk National University Observatory. Nineteen new times of minimum lights for GW Cep were determined and added to a collection of all other times of minima available to us. These data were then intensively analyzed, by reference to an O-C diagram, to deduce the general form of period variation for GW Cep. It was found that the O-C diagram could be interpreted as presenting two different forms of period change: an exclusively quasi-sinusoidal change with a period of 32.6 years and an eccentricity of 0.10; and a quasi-sinusoidal change with a period of 46.2 years and an eccentricity of 0.36 superposed on an upward parabola. Although a final conclusion is somewhat premature at present, the latter seems more plausible because late-type contact binaries allow an inter-exchange of both energy and mass between the component stars. The quasi-sinusoidal characteristics were interpreted in terms of a light-time effect due to an unseen tertiary component. The minimum masses of the tertiary component for both cases were calculated to be nearly the same as the
-ranges which is hardly detectable in a light curve synthesis. The upward parabolic O-C diagram corresponding to a secular period increase of about
was interpreted as mass being transferred from the lesser to more massive component. The transfer rate for a conservative case was calculated to be about
which is compatible with other W UMa-type contact binaries.
Development of Precise Lunar Orbit Propagator and Lunar Polar Orbiter's Lifetime Analysis
Song, Young-Joo ; Park, Sang-Young ; Kim, Hae-Dong ; Sim, Eun-Sup ;
Journal of Astronomy and Space Sciences, volume 27, issue 2, 2010, Pages 97~106
DOI : 10.5140/JASS.2010.27.2.097
To prepare for a Korean lunar orbiter mission, a precise lunar orbit propagator; Yonsei precise lunar orbit propagator (YSPLOP) is developed. In the propagator, accelerations due to the Moon's non-spherical gravity, the point masses of the Earth, Moon, Sun, Mars, Jupiter and also, solar radiation pressures can be included. The developed propagator's performance is validated and propagation errors between YSPOLP and STK/Astrogator are found to have about maximum 4-m, in along-track direction during 30 days (Earth's time) of propagation. Also, it is found that the lifetime of a lunar polar orbiter is strongly affected by the different degrees and orders of the lunar gravity model, by a third body's gravitational attractions (especially the Earth), and by the different orbital inclinations. The reliable lifetime of circular lunar polar orbiter at about 100 km altitude is estimated to have about 160 days (Earth's time). However, to estimate the reasonable lifetime of circular lunar polar orbiter at about 100 km altitude, it is strongly recommended to consider at least
degrees and orders of the lunar gravity field. The results provided in this paper are expected to make further progress in the design fields of Korea's lunar orbiter missions.
A Study on the Development of Playback Control Software for Mark5B VSI System
Oh, S.J. ; Yeom, J.H. ; Roh, D.G. ; Chung, H.S. ; Kim, K.D. ; Cappallo, Roger ;
Journal of Astronomy and Space Sciences, volume 27, issue 2, 2010, Pages 107~116
DOI : 10.5140/JASS.2010.27.2.107
We developed the playback control software for a high-speed playback system which is a component of the Korea-Japan Joint VLBI Correlator (KJJVC). The Mark5B system, which is a recorder and playback system used in the Korean VLBI Network (KVN), has two kinds of operation mode. That is to say, the station unit (SU) mode, which is for the present Mark4 system, and the VSI mode, which is for the new VLBI standard interface (VSI) system. The software for SU is already developed and widely used in the Mark4 type VLBI system, but the software for VSI has only been developed for recording. The new VLBI system is designed with a VSI interface for compatibility between different systems. Therefore, the playback control software development of the VSI mode is needed for KVN. In this work, we developed the playback control software of the Mark5B VSI mode. The developed playback control software consists of an application part for data playing back, a data input/output part for the VSI board, a module for the StreamStor RAID board, and a user interface part, including an observation time control part. To verify the performance of developed playback control software, the playback and correlation experiments were performed using the real observation data in Mark5B system and KJJVC. To check the observation time control, the data playback experiment was performed between the Mark5B and Raw VLBI Data Buffer (RVDB) systems. Through the experimental results, we confirmed the performance of developed playback control software in the Mark5B VSI mode.
Generation of Klobuchar Coefficients for Ionospheric Error Simulation
Lee, Chang-Moon ; Park, Kwan-Dong ; Ha, Ji-Hyun ; Lee, Sang-Uk ;
Journal of Astronomy and Space Sciences, volume 27, issue 2, 2010, Pages 117~122
DOI : 10.5140/JASS.2010.27.2.117
An ionospheric error simulation is needed for creating precise Global Positioning System (GPS) signal using GPS simulator. In this paper we developed Klobuchar coefficients n
(n = 1, 2, 3, 4) generation algorithms for simulator and verified accuracy of the algorithm. The algorithm extract those Klobuchar coefficients from broadcast (BRDC) messages provided by International GNSS Service during three years from 2006 through 2008 and curve-fit them with sinusoidal and linear functions or constant. The generated coefficients from our developed algorithms are referred to as MODL coefficients, while those coefficients from BRDC messages are named as BRDC coefficients. The maximum correlation coefficient between MODL and BRDC coefficients was found for
and the value was 0.94. On the other hand, the minimum correlation was 0.64 for the case of
. We estimated vertical total electron content using the Klobuchar model with MODL coefficients, and compared the result with those from the BRDC model and global ionosphere maps. As a result, the maximum RMS was 3.92 and 7.90 TECU, respectively.
Receiver DCB Estimation and Analysis by Types of GPS Receiver
Choi, Byung-Kyu ; Chung, Jong-Kyun ; Cho, Jeong-Ho ;
Journal of Astronomy and Space Sciences, volume 27, issue 2, 2010, Pages 123~128
DOI : 10.5140/JASS.2010.27.2.123
This paper analyzes that the global positioning system (GPS) receiver differential code bias (DCB) has effect on the estimation the ionosphere total electron content (TEC). The data from nine permanent GPS sites of the Korea Astronomy and Space Science Institute (KASI) were used for the estimation of the receiver DCB before (Trimble 4000 SSi) and after (Trimble NetRS) the receiver replacement, using the singular value decomposition method. The results showed that the estimated mean value of the receiver DCB varied from 0.11 ns (nanosecond) to 7.54 ns before the receiver replacement, but the receiver DCBs shoed large values than 20 ns except some stations after the replacement. The receiver DCB showed a relatively large difference by types of the receivers, and, as a result, it had a great effect on the estimation the ionosphere TEC using GPS.
Adaptive Coding and Modulation Scheme for Ka Band Space Communications
Lee, Jae-Yoon ; Yoon, Dong-Weon ; Lee, Woo-Ju ;
Journal of Astronomy and Space Sciences, volume 27, issue 2, 2010, Pages 129~134
DOI : 10.5140/JASS.2010.27.2.129
Rain attenuation can cause a serious problem that an availability of space communication link on Ka band becomes low. To reduce the effect of rain attenuation on the error performance of space communications in Ka band, an adaptive coding and modulation (ACM) scheme is required. In this paper, to achieve a reliable telemetry data transmission, we propose an adaptive coding and modulation level using turbo code recommended by the consultative committee for space data systems (CCSDS) and various modulation methods (QPSK, 8PSK, 4+12 APSK, and 4+12+16 APSK) adopted in the digital video broadcasting-satellite2 (DVB-S2).
Preliminary Design of Tracking Mount for Movable SLR
Park, Cheol-Hoon ; Son, Young-Su ; Kim, Byung-In ;
Journal of Astronomy and Space Sciences, volume 27, issue 2, 2010, Pages 135~144
DOI : 10.5140/JASS.2010.27.2.135
In this paper, we present the result of preliminary design of tracking mount for ARGO-M which is a movable satellite laser ranging (SLR) system developed by Korea Astronomy and Space Science Institute (KASI). The tracking mount consists of a couple of core parts such as driving motors, encoders and bearings, and the requirements of each parts are determined on the basis of the technical consideration. 2D and 3D models for tracking mount were preliminarily designed using the selected core parts. In order to evaluate the validity of the preliminarily design, the simulator to test the elevation axis was designed and manufactured. The test to check the tracking performance and system accuracy of the simulator was performed, and it was confirmed that the preliminary design meets the operating specifications. Additionally, it was found that the repetitive errors and hysteresis errors need to be improved by the additional control algorithm.
Phase and Amplitude Drift Research of Millimeter Wave Band Local Oscillator System
Lee, Chang-Hoon ; Je, Do-Heung ; Kim, Kwang-Dong ; Sohn, Bong-Won ;
Journal of Astronomy and Space Sciences, volume 27, issue 2, 2010, Pages 145~152
DOI : 10.5140/JASS.2010.27.2.145
In this paper, we developed a local oscillator (LO) system of millimeter wave band receiver for radio astronomy observation. We measured the phase and amplitude drift stability of this LO system. The voltage control oscillator (VCO) of this LO system use the 3 mm band Gunn oscillator. We developed the digital phase locked loop (DPLL) module for the LO PLL function that can be computer-controlled. To verify the performance, we measured the output frequency/power and the phase/amplitude drift stability of the developed module and the commercial PLL module, respectively. We show the good performance of the LO system based on the developed PLL module from the measured data analysis. The test results and discussion will be useful tutorial reference to design the LO system for very long baseline interferometry (VLBI) receiver and single dish radio astronomy receiver at the 3 mm frequency band.
Performance Improvement of Near Earth Space Survey (NESS) Wide-Field Telescope (NESS-2) Optics
Yu, Sung-Yeol ; Yi, Hyun-Su ; Lee, Jae-Hyeob ; Yim, Hong-Suh ; Choi, Young-Jun ; Yang, Ho-Soon ; Lee, Yun-Woo ; Moon, Hong-Kyu ; Byun, Yong-Ik ; Han, Won-Yong ;
Journal of Astronomy and Space Sciences, volume 27, issue 2, 2010, Pages 153~160
DOI : 10.5140/JASS.2010.27.2.153
We modified the optical system of 500 mm wide-field telescope of which point spread function showed an irregularity. The telescope has been operated for Near Earth Space Survey (NESS) located at Siding Spring Observatory (SSO) in Australia, and the optical system was brought back to Korea in January 2008. After performing a numerical simulation with the tested value of surface figure error of the primary mirror using optical design program, we found that the surface figure error of the mirror should be fabricated less than root mean square (RMS)
/10 in order to obtain a stellar full width at half maximum (FWHM) below
. However, we started to figure the mirror for the target value of RMS
/20, because system surface figure error would be increased by the error induced by the optical axis adjustment, mirror cell installation, and others. The radius of curvature of the primary mirror was 1,946 mm after the correction. Its measured surface figure error was less than RMS
/20 on the table of polishing machine, and RMS
/15 after installation in the primary mirror cell. A test observation performed at Daeduk Observatory at Korea Astronomy and Space Science Institute by utilizing the exiting mount, and resulted in
of stellar FWHM. It was larger than the value from numerical simulation, and showed wing-shaped stellar image. It turned out that the measured-curvature of the secondary mirror, 1,820 mm, was not the same as the designed one, 1,795.977 mm. We fabricated the secondary mirror to the designed value, and finally obtained a stellar FWHM of
after re-installation of the optical system into SSO NESS Observatory in Australia.
A Study on the Sundials of the Kang Family of Jinju
Kim, Sang-Hyuk ; Lee, Ki-Won ; Lee, Yong-Sam ;
Journal of Astronomy and Space Sciences, volume 27, issue 2, 2010, Pages 161~172
DOI : 10.5140/JASS.2010.27.2.161
In this paper, we investigate the sundials made by the Kang Family of Jinju in the later period of the Joseon dynasty in terms of their characteristics, functions and the manufacturing technique. One of the characteristics of these sundials is that the value of polar height (i.e., the latitude of Seoul), the name of manufacturer, 24 seasonal subdivisions and so forth are written on the surface. In particular, polar height is expressed as '
39' 15"' in all 12 sundials examined in this study. To investigate the manufacturing technology in terms of astronomy, we analyze the positions of gnomon and of the lines corresponding to 24 seasonal subdivisions (season lines) and to each hour (hour lines). To verify the accuracy of the positions, we use a planar projection method. That is, we obtain 2D images of the sundials using a camera or scanner, and compare these with astronomical calculations for the positions of gnomon and season/hour lines. We believe that this method will be very useful for the study of sundials preserved elsewhere.
VLBI Type Experimental Observation of GPS
Kwak, Young-Hee ; Kondo, Tetsuro ; Amagai, Jun ; Gotoh, Tadahiro ; Sasao, Tetsuo ; Cho, Jung-Ho ; Kim, Tu-Hwan ;
Journal of Astronomy and Space Sciences, volume 27, issue 2, 2010, Pages 173~180
DOI : 10.5140/JASS.2010.27.2.173
As a preparatory study for Global Positioning System-Very Long Baseline Interferometry (GPS-VLBI) hybrid system, we examined if VLBI type observation of the GPS signal is realizable through a test experiment. The test experiment was performed between Kashima and Koganei, Japan, with 110 km baseline. The GPS L1 and L2 signals were received by commercial GPS antennas, down-converted to video-band signals by specially developed GPS down converters, and then sampled by VLBI samplers. The sampled GPS data were recorded as ordinary VLBI data by VLBI recorders. The sampling frequency was 64 MHz and the observation time was 1 minute. The recorded data were correlated by a VLBI correlator. From correlation results, we simultaneously obtained correlation fringes from all 8 satellites above a cut-off elevation which was set to 15 degree. 87.5% of L1 fringes and 12.5% of L2 fringes acquired the Signal to Noise Ratios which are sufficient to achieve the group delay precision of 0.1nsec that is typical in current geodetic VLBI. This result shows that VLBI type observation of GPS satellites will be readily realized in future GPS-VLBI hybrid system.