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 ~ 2023
- 주제분류 자연과학 > 천문학 자연과학 분류의 다른 간행물
- 십진분류KDC 440DDC 520
권호리스트/논문검색
Volume 19 (2004년 12월) 18건
1.
2004.12
구독 인증기관 무료, 개인회원 유료
On the framework of a linearly perturbed Friedmann-Robertson-Walker spacetime, we derive an expression for the cosmological angular diameter distance affected by scalar and tensor perturbations. Our expression is applicable in linear order to distances in general FRW models. We study the effect of a stocastic gravitaional wave background on the two-point correlation function of the angular diameter distance fluctuations and, on the basis of this we also derive an expression for the power spectrum of the angular diameter distance fluctuations.
4,000원
2.
2004.12
구독 인증기관 무료, 개인회원 유료
In this review article the famous 'jet equation' in a Minkowski magnetosphere around the compact objects will be fully derived for the pedagogical purposes.
4,000원
3.
2004.12
구독 인증기관 무료, 개인회원 유료
In this paper, the intensity ratio of [O I] λ6300 and Hα lines, which plays an important role in the study of warm (or diffuse) ionized interstellar medium, is calculated assuming collisional ionization equilibrium (or coronal equilibrium). The calculated ratio is compared with the previous works, and with the observations, obtained by Reynolds (1989) and Reynolds et al. (1998) with the Wisconsin Ha Mapper facility, toward the directions that sample the faint interstellar emission-line background. The comparison confirms that most of the Ha originates from nearly fully ionized regions along the lines of sight rather than from partially ionized H I clouds or layers of H II on the surfaces of H I clouds.
3,000원
4.
2004.12
구독 인증기관 무료, 개인회원 유료
We analyzed the high resolution H,6 line spectra of CH Cygni obtained at the Bohyunsan Astronomical Observatory (BOAO) on April 2004. The temporal changes in the Hβ line profiles are reported. We obtained the equivalent widths of the Gaussian components. Using this we estimated the length of the gaseous nebula which emits the Hβ line and the mass loss rate from the star.
4,000원
5.
2004.12
구독 인증기관 무료, 개인회원 유료
Through time-series CCD photometry using a 155mm refractor, we found a new δ Scuti type variable star, HD 235428, near a known bright δ Scuti type star, DQ Cep. We performed follow-up observations using a 61cm telescope at Sobaeksan Optical Astronomy Observatory. Four frequencies have been derived by multiple-frequency analysis, which are 15.804, 5.498, 15.351 and 24.516cycle day−1 , respectively. V-amplitude of HD 235428 is ΔV = 0.026.
4,000원
6.
2004.12
구독 인증기관 무료, 개인회원 유료
Through time-series CCD photometry using a 130mm refractor of Busan Science Academy, we found a new δ Scuti type variable star, esc 03665-00576. We performed following observations using a 1.8m telescope of Bohyunsan Optical Astronomy Observatory. Three frequencies have been derived by multiple-frequency analysis, which are 10.968, 7.156 and 15.182cycle day−1, respectively. V-amplitude of esc 03665-00576 is ΔV= 0.04.
4,000원
7.
2004.12
구독 인증기관 무료, 개인회원 유료
We have carried out the high-resolution spectroscopic observations of Titan using BOES (Bohyunsan Echelle Spectrometer) to establish a standard spectral atlas of Titan. The observations were made on November 3, 4, 16 and 17, 2003 using a 300 11m fiber optics with a spectral resolving power of 30,000. The spectral atlas will be served as a reference for the future spectroscopic researches of Titan and other planetary objects. We were able to confirm CH4 absorption lines of the Kuiper bands, and find unidentified lines near 7500 Å
4,000원
8.
2004.12
구독 인증기관 무료, 개인회원 유료
We present the detailed description on the fiber techniques adopted in the BOES: the design concepts and manufacturing of the v grooves, the procedures of the fiber polishing, adhering of the fibers to the v grooves, and the axis alignment of the fiber input and exit. The high efficiency and throughput of the BOES imply that the adopted fiber arts and the other optical components were well designed and properly treated. We learned that the relatively low efficiency of the 80 micron fiber comparing with the 200 and 300 micron fibers comes from the seeing and the guiding effects not from the poor fiber handling.
4,000원
9.
2004.12
구독 인증기관 무료, 개인회원 유료
Observation environment of the Bohyunsan Optical Astronomy Observatory(BOAO) has been examined using various statistical data including real observation times versus allocated times and seeing statistics. The data have been collected from the observation logs of the 1.8m telescope in the period 1998 - 2004. New criteria have been set up to calculate a more realistic observation efficiency of the observatory. The new statistical analysis based on the new criteria gives the overall observation efficiency of BOAO as 38.6%, that is equivalent to 115.8 observable nights out of 300 allocatable nights. The seeing statistics shows that the mean seeing measured at the focal images is 2".3. The present study of the observation environment of BOAO suggests that differential photometry and spectroscopy should be preferred modes of observation to maximize the productivity of BOAO.
4,000원
10.
2004.12
구독 인증기관 무료, 개인회원 유료
An imaging spectrograph concept optimized for extended far-ultraviolet emission sources is presented. Although the design was originally developed for FIMS aboard the first Korean science satellite STSAT-l launched on September 27, 2003, no rigorous theoretical background of the spectrograph design has been published. The spectrograph design employs an off-axis parabolic cylinder mirror in front of a slit that guides lights to a diffraction grating. The concave grating provides moderate spatial resolution over a large field of view. This mapping capability is absent in most astronomical instruments but is crucial to the understanding of the nature of a variety of astrophysical phenomena. The aberration theory presented in this paper can be extended to holographic gratings in order to improve the spatial as well as the spectral resolutions.
4,000원
11.
2004.12
구독 인증기관 무료, 개인회원 유료
We have developed a tool for measuring optical aberrations of telescope. We adopt curvature sensing technique and use the least square method for finding the amplitudes of the Zernike polynomials. This tool runs under the PC Linux system and the PC windows system with Linux emulators such as Cygwin. The program for UNIX system is used for optical alignment of 1.8M optical telescope at the Bohyunsan Optical Astronomical Observatory (BOAO) and the PC based program is used for the Korea Astronomy Observatory (KAO) wide field telescope (named NEOPAT-3). Our tool is found to be efficient for precise measurement of the optical aberrations of telescopes.
4,000원
12.
2004.12
구독 인증기관 무료, 개인회원 유료
A high performance computing cluster for astronomical computations has been built at Korea Astronomy Observatory. The 64 node cluster interconnected with Gigabit Ethernet is composed of 128 Intel Xeon processors, 160 GB memory, 6 TB global storage space, and an LTO (Linear Tape-Open) tape library. The cluster was installed and has been managed with the Open Source Cluster Application Resource (OSCAR) framework. Its performance for parallel computations was measured with a three-dimensional hydrodynamic code and showed quite a good scalability as the number of computational cells increases. The cluster has already been utilized for several computational research projects, some of which resulted in a few publications, even though its full operation time is less than one year. As a major resource of the K∗Grid testbed, the cluster has been used for Grid computations, too.
4,000원
13.
2004.12
구독 인증기관 무료, 개인회원 유료
In this paper, we introduce the development of the large storage system in order to record the observed space radio signal in the Korean VLBI Network(KVN) with high-speed. The KVN is the Very Long Baseline Interferometery(VLBI) to observe the birth of star, the structure of space by constructing radio telescope with diameter 21m at the Seoul, Ulsan, Jeju from 2001 to 2007 years. To do this, Korea Astronomy Observatory joined the international consortium for developing the high-speed large storage system(Mark 5), which is developed by MIT Haystack observatory. The Mark 5 system based on hard disk has to record up to 1 Gbps the observed space radio signal. The main features of Mark 5 system are as follows; First it is able to directly record the input data to the hard disk without PC1(Peripheral Component Interconnect) internal bus, and the second, it has two hard disk banks, which are able to hot-swap ATA/IDE type very cheap up to 1 Gbps recording and playback. The third is that it follows the international VLBI standard interface hardware(VSI-H). Therefore it can be connect directly the VSI-H type system at the input/output. Finally it also supports e- VLBI(Electronic-VLBI) through the standard Gigabits Ethernet connection.
4,000원
14.
2004.12
구독 인증기관 무료, 개인회원 유료
In this paper, we describe a principle of the atomic frequency standard and clock system in VLBI(Very Long Baseline Interferometry). The hydrogen maser is a usual VLBI standard. During VLBI observations, signals emitted by distant sources of radio frequency energy(quasars) are received and recorded at several antennas. At each antenna(VLBI station), a very stable frequency standard(hydrogen maser) provides a reference signal which enables time-tagging to the quasar signals as they are being recorded on magnetic tapes or hard-disk modules. For each VLBl experiment, correlation of the time-tagged recorded information between the participating antennas is used to yield the arrival time differences of any specific quasar radio wave between the antennas. These time differences are used to calculate the relative antennas to each other. In this paper, we also introduce the KVN(Korean VLBI Network) atomic frequency standard and clock system.
4,000원
15.
2004.12
구독 인증기관 무료, 개인회원 유료
This paper describes the digital back-end system for getting the data to analyze the user observation mode by digitalize the analog data after receiving the space radio using the radio telescope, The received analog data will be digitalized by high-speed sampler with 1 Gsps for 4 channel frequency band of millimeter wave, and the digital data will be transported through the fiber-optic digital transmission system and WDM(wavelength division multiplex) to observation building, The wideband digital FIR(Finite Impulse Response) filters analyze the data for user observation mode to record the data in high-speed recorder with 1 Gbps. In this paper, we introduce the overall system configuration and features combined by various information and communication technology in radio astronomy briefly, which will be adopted by KVN(Korean VLBI Network).
4,000원
16.
2004.12
구독 인증기관 무료, 개인회원 유료
As a core project of the Korean Astronomical Data Center (KADC) in Korea Astronomy Observatory (KAO), we have constructed a framework of astronomical database using MySQL and JSP. MySQL database server is a powerful open source database management system, and JSP technology provides a simplified, fast way to create dynamic web content. Combined together, MySQL and JSP enable us to develop server-independent web-based applications efficiently in a short amount of time. The MySQL tables and JSP programs embedded in our database are built/written in a way to benefit both users and managers. We plan to expand our database by supplementing additional data in the near future. Our newly constructed database is expected to be the prototype of the Korean Virtual Observatory (KVO).
4,200원
17.
2004.12
구독 인증기관 무료, 개인회원 유료
We have constructed a database of Korean historical astronomical records. The database contains observational data recorded from BC 2183 to AD 1910. We have also built a webpage for searching through the database based on the following criteria: (1) dynasties (2) astronomical phenomena (3) reigning kings (4) references (5) keywords. Users may select two or more dynasties to search through the database for a certain phenomena, and compare data with those of other dynasties. The queried data can be primarily sorted by one critetion, and secondarily sorted by another, each in ascending or descending order. The search results give dates both in Solar and Lunisolar calendars, years and dates in Sexagenary cycle, dynasties, reigning kings, astronomical phenomena, and references. The database and webpage were constructed under the research project of the Korean Astronomical Data Center (KADC, http://kadc.kao.re.kr) in Korea Astronomy Observatory (KAO).
4,000원
18.
2004.12
구독 인증기관 무료, 개인회원 유료
In the past, radio astronomers have sought isolation from man-made signals by placing their telescopes in remote locations. These measures may no longer safeguard scientific observations, since NGSO satellite systems, particularly low-Earth orbit (LEO) systems, are usually designed to provide global or wide regional coverage. Further, radio astronomers have historically made their observations in the frequency bands allocated for their use by the member countries of the International Telecommunication Union (ITU). The science of radio astronomy could be adversely impacted by the deployment of large constellations of new non-geostationary orbiting (NGSO) satellites for telecommunications, navigation and Earth observation, and the proliferation of new, high-power broadcasting and telecommunication satellites in geostationary (GSO) orbits. Radio telescopes are extremely sensitive, and, in certain situations, signals from satellites can overwhelm the signals from astronomical sources. This paper describes the problem in detail and identifies ways to mitigate it without adversely affecting the continued vigorous growth of commercial space-based telecommunications.
4,000원
