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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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The Korean Space Science Society
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Volume 12, Issue 2 - Dec 1995
Volume 12, Issue 1 - Jun 1995
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SPECTROSCOPIC STUDIES OF STARBURST GALAXIES ; THE DYNAMICAL STRUCTURE OF BLUE COMPACT DWARF CALAXY HARO 6
Chun, Mun-Suk ; Moon, Hong-Kyu ; Sung, Eon-Chang ;
Journal of Astronomy and Space Sciences, volume 12, issue 1, 1995, Pages 1~13
We carried out photometric and spectroscopic observatious of the blue compact dwarf galaxy Haro 6 in the Virgo Cluster of Galaxies. The long-slit spectroscopy was employed at three position angles,
with CCD camera mounted on the Cassegrain Spectrograph. Based on the mean intrinsic axial ratio <
>=0.3, we derived inclination I of the system as
using our composite V-band CCD image. Careful analysis on the velocity field of the system shows an asymptotically fiat rotation curve with the maximum rotational velocity
reaches about 12km/sec. The calculation of the dynamical mass of Haro 6 with a simple mass model is briefly discussed with emphasis on the mass to luminosity ratio. From the IRAS Point Source Cataloque, we derived dust-to-gas ratio which indicates relatively low dust content, thus tempting us to conjecture the youth of the system.
EFFECTS OF DAMPING LENGTHS ON THE WIND VELOCITY FOR 32 CYG
Journal of Astronomy and Space Sciences, volume 12, issue 1, 1995, Pages 14~20
We calculated the wind velocities for 32 Cyg in order to understand how influence a damping length on the wind of supergiant driven by Alfven waves. Four cases,
=0.9, 1.0, 5.0, the ratio of the damping length to the supergiant's radius, and the damping length increasing linearly with the distance from the star, were compared. The results showed the forces by Alfven waves gave the major contribution to the wind velocity but the forces by the pressure and gravitation did little. The model for the damping length with the linear relation showed the rapid increased due to short damping length near the surface of the star.
THE LIGHT CURVE ANALYSIS OF AW CAM
Journal of Astronomy and Space Sciences, volume 12, issue 1, 1995, Pages 21~29
Lyrae-type eclipsing binary AW Cam was observed photoelectrically in three wavelength regions. The obtained UBV light curves of AW Cam were analyzed with two separate modes(mode 2 for detached systems and mode 5 for semi-detached ones) of the Wilson-Devinney binary mode. It is intended to resolve the discrepancy in AW Cam system that the photometrio mass ratio (q=0.21) derived by Russo and Milano (1983) is not consistent with the spectroscopic result (q=0.43) by Mammano et al.(1967). Our photomtric solutions derived with mode 2 are fitted better to the observed light curves than those of mode 5, supporting that AW Cam may be not a normal semi-detached system but a detached one. Three dimensional Roche configuration of AW Cam system calculated with the derived mass ratio (q=0.43) reveals that the less massive secondary with the confined within its inner Roche lobe, while the more massive rimary is in marginally contact. From the Roche geometry, the constancy of the orbital period and other photometric evidences of AW Cam, it is provisionally concluded that the system is an unevolved detached binary in is provisionally concluded that the system is an unevolved detached binary in the phase of case A evolution toward 'contact phase' rather than and evolved one in 'broken-contact phase' suggested by Giuricin and Mardrossian (1981).
PHOTOMETRIC AND RADIAL VELOCITY CURVES ANALYSES OF THE TRIPLE SYSTEM
Journal of Astronomy and Space Sciences, volume 12, issue 1, 1995, Pages 30~43
New UBVRI observations of triple star
Tau were made at Chungbuk Ntional University Observatory for 31 nights from Dec. 1990 to Jan. 1994. A total of 2930 photometric observations were obtained with 586 points for each filters, and BVRI light curves were constructed. From the primary light curves, the one times of primary minimum light was determined with a new light element. The photometric solutions of light curves for
Tau were calculated by using Wilson-Devinney method with our BVRI light curves and the BV light curves obtained by Grant(1959). We determined spectroscopic solutions that were satisfied with these two light curves and the radial velocity curves had been collected by Fekel and Tomkin (1982). From these values, absolute dimensions for this system were estimated. The radius and mass for the primary star are turned out to be
for the secondary star, respectively.
PHOTOMETRIC STUDY OF CONTACY BINARY AW UMa
Journal of Astronomy and Space Sciences, volume 12, issue 1, 1995, Pages 44~53
BVRI observatins of AW UMa were made from March to April during 13 nights in 1994 using the 35cm Schmidt-Cassegrain telescope of Department of Astronomy and Space Science, Chungbuk National University. A total of 1092 observations (273 in B, 273 in V, 273 in R, 273 in I) were obtained. We constructed the light curves of BVRI with these observations. The one time of primary minimum light of JD Hel 2449456.1502 and the two times of secondary minimum light of JD Hel 2449456.1502 and JD Hel 2449447.1567 were determined from our observations. Orbital period change of -0.d00000394 was determined from O-C diagram which was constructed with collected times of minimum lights. Mass transfer rate of
was derived using the period changing ratio. It is suggested that the inhomogeneous distribution of transferred matter around the secondary component would produce the irregular light variation of the AW UMa system.
MULTI-CHANNEL REMOTE SENSING CCD CONTROLLER DESING WITH MULTIPLEXING CONCEPT
Han, Won-Yong ; Yoo, Sang-Keum ; Kim, Byung-Jin ;
Journal of Astronomy and Space Sciences, volume 12, issue 1, 1995, Pages 54~65
We present a design study for a remote sensing camera system which can be operated in multi-channel mode simultaneously with several bandpass filters. The camera control electronics is based on the multiplexed driving concept, which can provide a variety of flexibility for system control parameters and its individual optimisation. The design can also be applied to any system with linear sensors or frame sensors according to its functional requirements. The system design parameters have been examined, including modification of driving waveforms for different types of sensors, waveforms for low-nosie readout circuit in analog chain, and synchronisation with other signal processing.
DESIGN OF A RISE TIME DISCRIMINATION CIRCUIT FOR X-RAY PROPORTIONAL COUNTER
Journal of Astronomy and Space Sciences, volume 12, issue 1, 1995, Pages 66~77
It is possible to distinguish X-ray events from non X-ray events in proportional conters using the method of rise time discrimination (RTD). In order to subtract non X-ray background, we have developed a simple RTD circuit which will be applied to the proportional counter planned for a sounding rocket experiment. The entire circuit consists of two parts ; the rise time measurement circuit and the time to amplitude conversion circuit which includes the self-calibration mode. From the test with X-ray detecting system, we obtained that the background can be rejected more than 80% in the energy band 2∼12 keV. However we confirmed that the RDT method is not proper to be used for the energy range above 12kV.
SOFTWARE DEVELOPMENT OF HIGH-PRECISION EPHEMERIDES OF SOLAR SYSTEM (II)
Journal of Astronomy and Space Sciences, volume 12, issue 1, 1995, Pages 78~89
We solved n-body problem about 9 planets, moon, and 4 minor planets with relativistic effect related to the basic equation of motion of the solar system. Perturbations including flgure potential of the earth and the moon and solid earth tidal effect were considered on this relativistic equation of motion. The orientations employed precession and nutation for the earth, and lunar libration model with Eckert's lunar libration model based on J2000.0 were used for the moon. Finally, we developed heliocentric ecliptic position and velocity of each planet using this software package named the SSEG (Solar System Ephemerides Generator) by long-term (more than 100 years) simulation on CRAY-2S super computer, through testing each subroutine on personal computer and short-time(within 800 dyas) running on SUN3/280 workstation. Epoch of input data JD2440400.5 were adopted in order to compare our results to the data archived from JPL's DE 200 by Standish and Newhall. Above equation of motion was integrated numerically having 1-day step-size interval through 40,000 days (about 110 years long) as total computing interval. We obtained high-precision ephemerides of the planets with maximum error, less
compared with DE200 data (except for mars and moon).
THE DETERMINATION OF PRECISE COORDINATES FOR BOHYUNSAN OPTICAL ASTRONOMY OBSERVATORY BY GPS
Journal of Astronomy and Space Sciences, volume 12, issue 1, 1995, Pages 90~101
We determined three dimensional precise WGS 84 corrdinates of two points in Bohyunsan Optical Astronomy Observatory using the GPS. One of the two points is the center on the top of pier for 1.8m telescope, and the other one is placed on the hill beside the dome of 1.8m telescope. We performed the simultaneous GPS observation at the KAO GPS station and Bohyunsan Obervatory for 5 days from December 18 to 22, 1993. We employed three Trimble 4000SST receivers for these observations. The observed data were processed by TRIMVEC-PLUS software of Trimble with the MBPS method and the Triple Difference L1/L2 ION free technique. Through this research, we determined WGS 83 latitude, longitude and height of 1.8m telescope in Bohyunsan Optical Astronomy Observatory with the values of
STATION-KEEPING MANEUVER SIMULATION FOR THE KOREASAT SPACECRAFT USING MISSION ANALYSIS SOFTWARE
Lee, Byoung-Sun ; Eun, Jong-Won ;
Journal of Astronomy and Space Sciences, volume 12, issue 1, 1995, Pages 102~111
A series of east/west and north/south station-keeping maneuvers were simulated for the KOREAST spacecraft which has to be maintained within
0.05 at the nominal longitude of
E. Weekly an biweekly based station-deeping maneuver plannings were used, and weekend maneuvers were avoided. All of the station-keeping maneuver plannings and executions were performed using KOREASTA Mission Analysis Software on VAX/VMS operating system. Fourteen weeks station-keeping maneuvers were performed and various station-keeping orbital parameters were obtained.
THE BEAM POINTING OF COMMUNICATIN SATELLITE IN GEOSYNCHRONOUS INCLINED ORBIT
Journal of Astronomy and Space Sciences, volume 12, issue 1, 1995, Pages 112~122
We assume that the KOREASAT fails the entry of the geostationary orbit due to the error at the apogee kick motor firing. A simulation is done for the satellite that has a geosynochronous orbit with a non-zero degree inclination angle due to the failure at the apogee kick motor firing caused by the unbalance of the fuel storage and the spin of the thrust vector, etc. We analyzed the evolution of the orbit using the perturbation theory and calculated the changes of the eccentricity and the inclination. WHen a communication satellite has the figure eight trajectory, the beam point also traces the satellite. In this paper, We develope an algorithm to attack the above problem by stabilizing the beam point using the adjustment of the roll angle of the satellite. The spin action on the polarization plane that occurs when a satellite passes the ascending node and descending node affects the efficiency of the communication a lot, so we did another simulation for the better yaw angle adjustment for the KOREASAT to reduce the spin actino on the polarization plane.
CORRECTION OF THE TRACKING DATA OF AN ARTIFICIAL SATELLITE CONSIDERING THE EARTH ATMOSPHERE AND LIGHT TIME EFFECTS
Journal of Astronomy and Space Sciences, volume 12, issue 1, 1995, Pages 123~132
We developed a S/W system to simulate the orbit tracking data as nearly equal as the real data obtained at the tracking antenna by modeling various causes that could have effects on the tracking data (range, range rate, azimuth, elevation) of an artificial satellite. Using the S/W developed we produced delay values of tracking data due to the light-time effect and the terrestrial atmosphere. According to the simulation results due to the Earth atmosphere, the values delayed by the troposhpere were increased as the temperature, relative humidity, and pressure of the troposphere are more larger. However, delay values due to the ionosphere were dependent on both the maximum electron density and the frequencies used. They are more and more increased as the maximum electron density and frequency are more larger. And the delaying values by the light-time effect are more larger by the fast orbital motion as the altitude of an artificial satellite is more lower.
THE ORBIT DETERMINATION OF LEO SATELLITES USING EXTENDED KALMAN FILTER
Journal of Astronomy and Space Sciences, volume 12, issue 1, 1995, Pages 133~142
We studied the nonlinear estimation problem of extended Kalman filter and appled this method to LEO satellite system. Through this method the performance of extended Kalman filter was analyzed. There were certain presumption taken; J2 and atmospheric drag were simply considered in the dynamic model of LEO satellite and the system noise error of
=10m/s was presumed in the observation data. As results of this simulation, the overall state estimation errors of extended Kalman filter were within the presumed error range and also the ability of performance was maximized when the condition was the state process noise Q has the 1/10 level of covariance matrix Po.
EXTENDED KALMAN FILTERING OF SATELLITE DOPPLER TRACKING DATA AND IT'S APPLICATION TO ORBIT DETERMINATION PROBLEMS
Journal of Astronomy and Space Sciences, volume 12, issue 1, 1995, Pages 143~156
Using a directional antenna, the Doppler effect of satellites can be detected and the orbital elements can be obtained by the Extended Kalman Filter with the observed frequency shift data. We obtained the orbital elements of NOAA-11 by the application of the Extended Kalman Filter type algorithm to the Doppler shift data of NOAA-11d and discussed the accuracy and the credibility of this algorithm.