Go to the main menu
Skip to content
Go to bottom
REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
> Journal Vol & Issue
Journal of Astronomy and Space Sciences
Journal Basic Information
Journal DOI :
The Korean Space Science Society
Editor in Chief :
Volume & Issues
Volume 26, Issue 4 - Dec 2009
Volume 26, Issue 3 - Sep 2009
Volume 26, Issue 2 - Jun 2009
Volume 26, Issue 1 - Mar 2009
Selecting the target year
CCD Photometric Observations and Light Curve Synthesis of the Near-Contact Binary XZ Canis Minoris
Kim, Chun-Hwey ; Park, Jang-Ho ; Lee, Jae-Woo ; Jeong, Jang-Hae ; Oh, Jun-Young ;
Journal of Astronomy and Space Sciences, volume 26, issue 2, 2009, Pages 141~156
DOI : 10.5140/JASS.2009.26.2.141
Through the photometric observations of the near-contact binary, XZ CMi, new BV light curves were secured and seven times of minimum light were determined. An intensive period study with all published timings, including ours, confirms that the period of XZ CMi has varied in a cyclic period variation superposed on a secular period decrease over last 70 years. Assuming the cyclic change of period to occur by a light-time effect due to a third-body, the light-time orbit with a semi-amplitude of 0.0056d, a period of 29y and an eccentricity of 0.71 was calculated. The observed secular period decrease of
was interpreted as a result of simultaneous occurrence of both a period decrease of
by angular momentum loss (AML) due to a magnetic braking stellar wind and a period increase of
by a mass transfer from the less massive secondary to the primary components in the system. In this line the decreasing rate of period due to AML is about 3 times larger than the increasing one by a mass transfer in their absolute values. The latter implies a mass transfer of
from the less massive secondary to the primary. The BV light curves with the latest Wilson-Devinney binary code were analyzed for two separate models of 8200K and 7000K as the photospheric temperature of the primary component. Both models confirm that XZ CMi is truly a near-contact binary with a less massive secondary completely filling Roche lobe and a primary inside the inner Roche lobe and there is a third-light corresponding to about 15-17% of the total system light. However, the third-light source can not be the same as the third-body suggested from the period study. At the present, however, we can not determine which one between two models is better fitted to the observations because of a negligible difference of
between them. The diversity of mass ratios, with which previous investigators were in disagreement, still remains to be one of unsolved problems in XZ CMi system. Spectroscopic observations for a radial velocity curve and high-resolution spectra as well as a high-precision photometry are needed to resolve some of remaining problems.
BVR Standardization of the CCD Photometric System of Chungbuk National University Observatory
Jeong, Jang-Hae ; Lee, Yong-Sam ; Kim, Chun-Hwey ; Yoon, Yo-Na ;
Journal of Astronomy and Space Sciences, volume 26, issue 2, 2009, Pages 157~170
DOI : 10.5140/JASS.2009.26.2.157
BVR observations for 52 standard stars were performed using the 1-m reflecter with 2K CCD System of Chungbuk National University Observatory (CBNUO) in 2008. We obtained 1,322 CCD images to establish a correlation between our bvr system and the standard Johnson-Cousins BVR system. We derived the tentative equations of transformation between then as follows; V = v-0.0303(B - V) + 0.0466 B - V = 1.3475(b - v) - 0.0251 V - R = 1.0641(v - r) - 0.0125 Using these equations the magnitudes in V, B-V, and V-R for 197 stars were obtained.
The Earth-Moon Transfer Trajectory Design and Analysis using Intermediate Loop Orbits
Song, Young-Joo ; Woo, Jin ; Park, Sang-Young ; Choi, Kyu-Hong ; Sim, Eun-Sup ;
Journal of Astronomy and Space Sciences, volume 26, issue 2, 2009, Pages 171~186
DOI : 10.5140/JASS.2009.26.2.171
Various Earth-Moon transfer trajectories are designed and analyzed to prepare the future Korea's Lunar missions. Minimum fuel trajectory solutions are obtained for the departure year of 2017, 2020, 2022, and every required mission phases are analyzed from Earth departure to the final lunar mission orbit. N-body equations of motion are formulated which include the gravitational effect of the Sun, Earth and Moon. In addition, accelerations due to geopotential harmonics, Lunar J2 and solar radiation pressures are considered. Impulsive high thrust is assumed as the main thrusting method of spacecraft with launcher capability of KSLV-2 which is planned to be developed. For the method of injecting a spacecraft into a trans Lunar trajectory, both direct shooting from circular parking orbit and shooting from the multiple elliptical intermediate orbits are adapted, and their design results are compared and analyzed. In addition, spacecraft's visibility from Deajeon ground station are constrained to see how they affect the magnitude of TLI(Trans Lunar Injection) maneuver. The results presented in this paper includes launch opportunities, required optimal maneuver characteristics for each mission phase as well as the trajectory characteristics and numerous related parameters. It is confirmed that the final mass of Korean lunar explorer strongly depends onto the initial parking orbit's altitude and launcher's capability, rather than mission start time.
Analysis of KVN 21m Radio Antenna Optics using Ray-Tracing Method
Bae, Jae-Han ; Byun, Do-Young ;
Journal of Astronomy and Space Sciences, volume 26, issue 2, 2009, Pages 187~198
DOI : 10.5140/JASS.2009.26.2.187
In this work, we calculate drop in antenna gain, aperture phase distribution, and antenna pointing shift of KVN(Korean VLBI Network) 21m shaped Cassegrain antenna due to misalignments of antenna optics using ray-tracing method. The misalignments we considered are axial displacement of feed, axial displacement of sub-reflector, lateral displacement of feed, lateral displacement of sub-reflector, and sub-reflector tilt. Calculations are performed not only when these misalignments exist separately, but also when they exist at the same time. Although ray-tracing method is based on geometric optics which does not consider electromagnetic effects, we expect that this work enables us to align antenna optics which give the maximum gain.
Orbit Prediction using Broadcast Ephemeris for GLONASS Satellite Visibility Analysis
Kim, Hye-In ; Park, Kwan-Dong ;
Journal of Astronomy and Space Sciences, volume 26, issue 2, 2009, Pages 199~210
DOI : 10.5140/JASS.2009.26.2.199
Even though there are several Global Navigation Satellite Systems under development, only GPS and GLONASS are currently available for satellite positioning. In this study, GLONASS orbits were predicted from broadcast ephemeris using the 4th-order Runge-Kutta numerical integration. For accuracy validation, predicted orbits were compared with precise ephemeris. The RMS(Root Mean Square) and maximum 3-D errors were 14.3 km and 17.4 km for one-day predictions. In case of 7-day predictions, the RMS and maximum 3-D errors were 15.7 and 40.1 km, respectively. Also, the GLONASS satellite visibility predictions were compared with real observations, and they agree perfectly except for several epochs when the satellite signal was blocked by nearby buildings.
Comparison of Tropospheric Signal Delay Models for GNSS Error Simulation
Kim, Hye-In ; Ha, Ji-Hyun ; Park, Kwan-Dong ; Lee, Sang-Uk ; Kim, Jae-Hoon ;
Journal of Astronomy and Space Sciences, volume 26, issue 2, 2009, Pages 211~220
DOI : 10.5140/JASS.2009.26.2.211
As one of the GNSS error simulation case studies, we computed tropospheric signal delays based on three well-known models (Hopfield, Modified Hopfield and Saastamoinen) and a simple model. In the computation, default meteorological values were used. The result was compared with the GIPSY result, which we assumed as truth. The RMS of a simple model with Marini mapping function was the largest, 31.0 cm. For the other models, the average RMS is 5.2 cm. In addition, to quantify the influence of the accuracy of meteorological information on the signal delay, we did sensitivity analysis of pressure and temperature. As a result, all models used this study were not very sensitive to pressure variations. Also all models, except for the modified Hopfield model, were not sensitive to temperature variations.
GPS Receiver and Satellite DCB Estimation using Ionospheric TEC
Choi, Byung-Kyu ; Cho, Sung-Ki ; Lee, Sang-Jeong ;
Journal of Astronomy and Space Sciences, volume 26, issue 2, 2009, Pages 221~228
DOI : 10.5140/JASS.2009.26.2.221
We estimated the receiver and satellite differential code bias(DCB) based on the ionospheric total electron content(TEC) estimation method. The GPS network which has been operated by the Korea Astronomy and Space Science Institute(KASI) was designed to calculate TEC. The receiver and satellite DCB values were obtained from the weighted least square method with time interval for one hour. The results represented that the receiver DCB values are mostly varying within
meter and are derived comparatively stable within three days. The estimated mean values of the satellite DCB show the maximum and minimum values of 4.09 nano-second(ns), -6.28ns respectively. We could detect great variations of TEC over 9 TECU difference at any time when the DCB sets were applied to TEC estimation.
Precise Orbit Determination of LEO Satellite Using Dual-Frequency GPS Data
Hwang, Yoo-La ; Lee, Byoung-Sun ; Kim, Jae-Hoon ; Yoon, Jae-Cheol ;
Journal of Astronomy and Space Sciences, volume 26, issue 2, 2009, Pages 229~236
DOI : 10.5140/JASS.2009.26.2.229
KOorea Multi-purpose SATellite(KOMPSAT)-5 will be launched at 550km altitude in 2010. Accurate satellite position(20 cm) and velocity(0.03 cm/s) are required to treat highly precise Synthetic Aperture Radar(SAR) image processing. Ionosphere delay was eliminated using dual frequency GPS data and double differenced GPS measurement removed common clock errors of both GPS satellites and receiver. SAC-C carrier phase data with 0.1 Hz sampling rate was used to achieve precise orbit determination(POD) with ETRI GNSS Precise Orbit Determination(EGPOD) software, which was developed by ETRI. Dynamic model approach was used and satellite's position, velocity, and the coefficients of solar radiation pressure and drag were adjusted once per arc using Batch Least Square Estimator(BLSE) filter. Empirical accelerations for sinusoidal radial, along-track, and cross track terms were also estimated once per revolution for unmodeled dynamics. Additionally piece-wise constant acceleration for cross-track direction was estimated once per arc. The performance of POD was validated by comparing with JPL's Precise Orbit Ephemeris(POE).
The First Telescope in the Korean History I. Translation of Jeong's Report
Ahn, Sang-Hyeon ;
Journal of Astronomy and Space Sciences, volume 26, issue 2, 2009, Pages 237~266
DOI : 10.5140/JASS.2009.26.2.237
In 1631 A.D. Jeong Duwon, an ambassador of the Joseon dynasty was sent to the Ming dynasty. There he met
Rodrigues, a Jesuit missionary, in Dengzhou of Shandong peninsula. The missionary gave the ambassador a number of results of latest European innovations. A detailed description on this event was written in 'Jeong's official report regarding a message from an European country'(西洋國奇別狀啓), which is an important literature work to understand the event. Since the document was written in classical Chinese, we make a comprehensive translation to Korean with detailed notes. According to the report, the items that Rodrigues presented include four books written in Chinese that describe European discoveries about the world, a report on the tribute of new cannons manufactured by Portuguese in Macao, a telescope, a flintlock, a Foliot-type mechanical clock, a world atlas drawn by Matteo Ricci, an astronomical planisphere, and a sun-dial. We discuss the meaning of each item in the Korean history of science and technology. In particular, Jeong's introduction is an important event in the history of Korean astronomy, because the telescope he brought was the first one to be introduced in Korean history. Even though king Injo and his associates of the Joseon dynasty were well aware of the value as military armaments of new technologies such as telescopes, cannons, and flintlocks, they were not able to quickly adopt such technologies to defend against the military threat of Jurchen. We revisit the reason in view of the general history of science and technology of east-Asian countries in the 17th century.
Analysis and Design of the Automatic Flight Dynamics Operations For Geostationary Satellite Mission
Lee, Byoung-Sun ; Hwang, Yoo-La ; Park, Sang-Wook ; Lee, Young-Ran ; Galilea, Javier Santiago Noguero ;
Journal of Astronomy and Space Sciences, volume 26, issue 2, 2009, Pages 267~278
DOI : 10.5140/JASS.2009.26.2.267
Automation of the key flight dynamics operations for the geostationary orbit satellite mission is analyzed and designed. The automation includes satellite orbit determination, orbit prediction, event prediction, and fuel accounting. An object-oriented analysis and design methodology is used for design of the automation system. Automation scenarios are investigated first and then the scenarios are allocated to use cases. Sequences of the use cases are diagramed. Then software components and graphical user interfaces are designed for automation. The automation will be applied to the Communication, Ocean, and Meteorology Satellite (COMS) flight dynamics system for daily routine operations.