간행물
천문학논총 KCI 등재 Publications of the Korean Astronomical Society
- 발행기관 한국천문학회
- 자료유형 학술지
- 간기 연3회
- ISSN 1225-1534 (Print)2287-6936 (Online)
- 수록기간 1984 ~ 2024
- 주제분류 자연과학 > 천문학 자연과학 분류의 다른 간행물
- 십진분류KDC 440DDC 520
권호리스트/논문검색
Volume 23 Issue 2 (2008년 12월) 11건
1.
2008.12
구독 인증기관 무료, 개인회원 유료
From the short-period variability survey (SPVS), we obtained time-series BV CCD images in the region of an open cluster M50 (NGC 2323) for 10 nights from 2008 February 9 to 27. The observation was performed using a small refracting telescope ( ϕ=155mm, f=1050mm) in Bohyunsan Optical Astronomy Observatory (BOAO). M50 is included in the observing field of ASAS (The All Sky Automated Survey). In the region of M50, we found 8 new variable stars including two δ Scuti stars with short-periods and very small amplitudes. There are known nine variable stars by the catalogues of ASAS and GCVS in the region. We confirmed the variability of the known variable stars for six and non-variability for three.
4,000원
2.
2008.12
구독 인증기관 무료, 개인회원 유료
Scattering of incident light by the interstellar dust is usually approximated by Henyey-Greenstein scattering phase function. Recently, Draine (2003) proposed a new analytic phase function with two parameters. We describe an algorithm to generate random numbers distributed according to the Draine’s function, and compare two phase functions. It is also derived exact solutions of two parameters for given values ⟨cosθ⟩ and ⟨cos2θ⟩ . It is found that Henyey-Greenstein function with g = ⟨cosθ⟩ provides a good approximation for ${\lambda}\;>\;2000{\AA}$. At shorter wavelengths, more realistic phase function may be needed for radiative transfer models.
4,000원
3.
2008.12
구독 인증기관 무료, 개인회원 유료
We present analytical approximations for calculating the scattering and escape of non-ionizing photons from a plane-parallel medium with uniformly illuminated by external sources. We compare the results with the case of a spherical dust cloud. It is found that more scattering and absorption occur in the plane-parallel geometry than in the spherical geometry when the optical depth perpendicular to the plane and the radial optical depth of the sphere are the same. The results can provide an approximate way to estimate radiative transfer in a variety interstellar conditions and can be applied to the dust-scattered diffuse Galactic light.
4,000원
4.
2008.12
구독 인증기관 무료, 개인회원 유료
We present the results of image simulations of 43.1 GHz SiO maser emission toward a Mira variable using the KVN (Korean VLBI Network) and other facilities which can make joint VLBI experiments with the KVN. To test the imaging capability of the KVN we used the image of SiO masers in the simulation obtained by the VLBA, which is considered to be the optimum VLBI facility at present to study SiO masers toward evolved stars. The simulated images of SiO maser emission confirm that coordinate VLBI expriments of KVN with several more stations in Japan or in the neighborhood of Korean Peninsula are necessary to exert the functional benefit of the KVN as the first mm VLBI facility which can perform simultaneous observations at four different frequency bands.
4,000원
5.
2008.12
구독 인증기관 무료, 개인회원 유료
We have performed the flat-fielding correction for the Hα full-disk monitoring system of KASI (Korea Astronomy and Space Science Institute), which is installed in the Solar Flare Telescope (SOFT) at the top of Bohyun Mountain. For this, we used a new method developed by Chae (2004), to determine the flat pattern from a set of relatively shifted images. Using this method, we successfully obtained the flat pattern for Hα full-disk observations and compared our result with the image observed in Catania Astrophysical Observatory. The method that we used in this study seems to be quite powerful to obtain the flat image for solar observations. In near future, we will apply this method for the flat-fielding correction of all solar imaging instruments in KASI.
4,000원
6.
2008.12
구독 인증기관 무료, 개인회원 유료
Korea Astronomy and Space Science Institute (KASI), direct decendant of Korea National Astronomy Observatory, has been publishing Korean Astronomical Almanac since in 1976. The almanac contains essential data in our daily lives such as the times of sunrise, sunset, moonrise, and moonset, conversion tables between luni-solar and solar calendars, and so forth. So, we are planning to register Korean astronomical almanac data for national Standard Reference Data(SRD), which is a scientific/technical data whose the reliablity and the accuracy are authorized by scientific analysis and evalution. To be certificated as national SRD, reference data has to satisfy several criteria such as traceability, consistency, uncertainty, and so on. Based on similarity among calculation processes, we classified astronomical almanac data into three groups: Class I, II, and III. We are planning to register them for national SRD in consecutive order. In this study, we analyzed Class I data which is aimed to register in 2009, and presented the results. Firstly, we found that the traceability and the consistency can be ensured by the usage of NASA/JPL DE405 ephemeris and by the comparsion with international data, respectively. To evaluate uncertainty in Class I data, we solved the mathematical model and determined the factors influencing the calculations. As a result, we found that the atmospheric refraction is the main factor and leads to a variation of ±16 seconds in the times of sunrise and sunset. We also briefly review the histories of astronomical almanac data and of standard reference data in Korea.
4,200원
7.
2008.12
구독 인증기관 무료, 개인회원 유료
It has been considered that 'exhausted eclipses' (日食旣) were total eclipses. However, modern precise calculations show that a significant fraction of such records are not realized to be total. Thus we doubt that the two concepts are equivalent. Here we investigate the meaning of 'exhausted eclipses' in the east-Asian history. We first find that eclipses of magnitude greater than 0.8 were regarded as 'exhausted eclipses' by a Korean astronomer of the 18th-century Choson dynasty. His notion was based upon the definition of 'exhausted eclipses' in the ephemerides of pre-modern Chinese dynasties. According to those ephemerides, the 'exhausted eclipses', whose magnitude is greater than 0.8, have the first contact at the western part of the solar disk and the fourth contact at the eastern part of the solar disk. A simple geometrical calculation shows that such cases really occur when the magnitude of eclipse is greater than 0.7. We pointed out that such an ancient definition might not be impractical for ancient astronomers, because the uncertainty of eclipse magnitude estimated by ancient Chinese ephemerides was 10% and the human sight has a spatial resolution of 1.2 arcmin, which is approximately one twentieth of the Sun's angular diameter.
4,000원
8.
2008.12
구독 인증기관 무료, 개인회원 유료
A software simulator is developed for verifying the VLBI Correlation Subsystem (VCS) trial product hardware. This software simulator includes the delay tracking, fringe rotation, bit-jump, FFT analysis, re-quantization, and auto/cross-correlation functions so as to confirm the function of the VCS trial product hardware. To verify the effectiveness of the developed software simulator, we carried out experiments using the simulation data which is a mixed signal with white noise and tone signal generated by software. We confirmed that the performance of this software simulator is similar as that of the hardware system. In case of spectral analysis and re-quantization experiment, a serious problem of the VCS hardware, which is not enough for expressing the data stream of FFT results specified in VCS hardware specification, was found by this software simulator. Through the experiments, the performance of software simulator was verified to be efficient. In future, we will improve and modify the function of software simulator to be used as a software correlator of Korea-Japan Joint VLBI Correlator (KJJVC).
5,200원
9.
2008.12
구독 인증기관 무료, 개인회원 유료
In this paper, we introduce the performance evaluation and development of Raw VLBI Data Buffer(RVDB) system for the synchronized playback processing of observed data in Korea-Japan Joint VLBI Correlator(KJJVC). The high-speed correlation processing system is under development so that the radio data obtained with 8192 channels and 8 Gbps speed from 16 stations will be able to be processed. When the recorded data of each station are played to correlator, the time synchronization of each station is very important because the correlator should process the data obtained with same time and condition. There are many types of recorder systems in the East Asia VLBI Network (EAVN). Therefore it is required to prepare the special time synchronized playback processing system to synchronize the time tag of observed data. The developed RVDB system consists of Data Input Output(DIO), 10GbE switch, and Disk Data Buffer(DDB). It can record the data with maximum 2 Gbps speed, and can play back the data to correlator with nominal 2 Gbps speed. To enable to play back the data of different playback system to the correlator, we developed the high-speed time synchronized playback processing system. We carried out the experiments of playing back and correlation for gigabit correlator and VCS trial product so as to confirm the performance of developed time synchronized playback processing system. In case of online and offline playing back experiment for gigabit correlator, we confirmed that the online and offline correlation results were the same. In case of playing back experiment for VCS trial product, we verified that the wide band and narrow band correlation results were also the same. Through the playing back experiments of RVDB system, the effectiveness of developed RVDB system was verified. In this paper, the system design, construction and experimental results are shown briefly.
5,100원
10.
2008.12
구독 인증기관 무료, 개인회원 유료
The International Astronomy Olympiad (IAO) was established by the Euro-Asian Astronomical Society in order to disseminate astronomical knowledge, promote international cooperation in astronomical education area and recognize the importance of astronomy in far-reaching field of science and human culture. The first IAO competition was held at the Special Astrophysical Observatory of the Russian Academy of Sciences located in the north Caucasus of Russia in 1996. Since then, it has been held every year. This paper describes the present status of the IAO main regulations regarding its operation and major results by year, related institutions, and organizations. We created a scientific inquiry framework to analyze past IAO problems in the recognitive aspect in order to measure levels of the scientific knowledges and the scientific thinking abilities. Through this analysis, we can understand the current status of the IAO, and examine the future direction of Korea Astronomy Olympiad. Also, we can make preparation for the IAO competition and the education of delegates.
4,500원
11.
2008.12
구독 인증기관 무료, 개인회원 유료
Productivity of the Giant Magellan Telescope is estimated based on the annual number of papers produced by the currently operating large telescopes such as the telescope at the ESO La Silla observatory, CFHT, AAT, the Magellan telescopes, ESO VLT, Japanese Subaru, the Gemini telescopes, and the Keck telescopes. We find that the amount of papers produced by a large telescope is roughly proportional to the diameter of its primary mirror. With this fact, we estimate the SCI-paper productivity of the Giant Magellan Telescope by extrapolating the productivity of the above-mentioned large telescopes. Moreover, according to the paper written in 2001 by Benn and Sanchez, the amount of highly-cited papers produced by a large telescope is roughly proportional to the light-gathering power of the telescope or the square of the diameter. Hence, we survey the productivity of Nature-class papers of the large telescopes and extrapolate the relationship to estimate the productivity of the Nature-class papers by using the Giant Magellan telescope of a filled aperture 21.4 meters in diameter. We expect that Korean astronomers will be able to produce annually 60 SCI-class papers and 20 Nature-class papers with high scientific impact by using the telescope-time corresponding to the 10% share of the Giant Magellan Telescope.
4,000원
