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 15 Issue 1 (2000년 6월) 6건
1.
2000.06
구독 인증기관 무료, 개인회원 유료
Since Goldreich and Julian's pioneering work in 1969, the pulsar magnetosphere theory has been dramatically developed for theorists to possess an elegant axisymmetric, stationary model. Based on this development the black hole magnetosphere theory has also been established in the last 30 years. Such theoretical developments will be reviewd equation by equation in this paper.
4,500원
2.
2000.06
구독 인증기관 무료, 개인회원 유료
The lens mass determined from the photometrically obtained Einstein time scale suffers from large uncertainty due to the lens parameter degeneracy. The uncertainty can be substantially reduced if the mass is determined from the lens proper motion obtained from astrometric measurements of the source image centroid shifts, δθc δθc , by using high precision interferometers from space-based platform such as the Space Interferometry Mission (SIM), and ground-based interferometers soon available on several 8-10m class telescopes. However, for the complete resolution of the lens parameter degeneracy it is required to determine the lens parallax by measuring the parallax-induced deviations in the centroid shifts trajectory, Δδθc Δδθc aloe. In this paper, we investigate the detectabilities of δθc δθc and Δδθc Δδθc by determining the distributions of the maximum centroid shifts, f(δθc,max) f(δθc,max) , and the average maximum deviations, (<Δδc,max>) (<Δδc,max>) , for different types of Galactic microlensing events caused by various masses. From this investigation, we find that as long as source stars are bright enough for astrometric observations it is expected that f(δθc) f(δθc) for most events caused by lenses with masses greater than 0.1 M⨀ M⨀ regardless of the event types can be easily detected from observations by using not only the SIM (with a detection threshold but also the δθth\~3μas) δθth\~3μas) but also the ground-based interferometers (withδθth\~3μas) (withδθth\~3μas) . However, from ground-based observations, it will be difficult to detect Δδθc Δδθc for most Galactic bulge self-lensing events, and the detection will be restricted only for small fractions of disk-bulge and halo-LMC events for which the deviations are relatively large. From observations by using the SIM, on the other hand, detecting Δδθc Δδθc will be possible for majority of disk and halo events and for a substantial fraction of bulge self-lensing events. For the complete resolution of the lens parameter degeneracy, therefore, SIM observations will be essential.
4,000원
3.
2000.06
구독 인증기관 무료, 개인회원 유료
We have analyzed 221 data of daily sunspot observations made during the period of January 1 to December 30 in 1999 and presented the daily relative sunspot numbers. During the year of 1999, our annual average of relative sunspot numbers is found to be 130.1. This number is obtained from the averaged daily number of 6.7 spot groups, in which there are about 45.9 distinct spots observed. According to the appearance of 384 spot groups, our analysis shows that the mean life time of spot group is about 5 day and 4.6 hours.
4,000원
4.
2000.06
구독 인증기관 무료, 개인회원 유료
We determined the precise three dimensional WGS84 Coordinates and the sea level height of Seoul Radio Astronomy Observatory (SRAO). In this study, we performed the simultaneous GPS observations at SRAO and Seoul GPS Reference Station(SGRS) of Korea Astronomy Observatory(KAO) for 3.5 hours from 17KST on October 27, 1999. We employed two different antennas, i.e., chokering antenna at SGRS of KAO and L1/L2 compact with groundplane antenna at SRAO. But we employed same type of receivers, i.e., Trimble 4000SSI at both observing places. The observed data were processed by GPSURVEY 2.30 software of Trimble with L1/L2 ION Free technique and broadcasting ephemeris of GPS Satellites because of very short baseline between SGRS of KAO and SRAO. We determined WGS84 latitude, longitude, height and the sea level height of SRAO with 37∘27′15.′6846N±0.′0004,126∘57′19.′0727E±0.′0002,204.89m±0.02m,181.38m±0.17m 37∘27′15.′6846N±0.′0004,126∘57′19.′0727E±0.′0002,204.89m±0.02m,181.38m±0.17m , respectively.
3,000원
5.
2000.06
구독 인증기관 무료, 개인회원 유료
We have analyzed the frequency sharing in the range of 71-275 GHz, which was adopted as a main topic of the WARC-2000 at the previous conference WARC-97. Though the technology of the active services has not been fully developed in this frequncy range, the heavy usage of this technology is expected in foreseeable future. To protect the passive services from spurious and out-of-band emissions of active services, realignment of the spectrum between 71 GHz and 275 GHz is strongly required. In addition, some effort should be made to allocate special bands for the radio astronomy service.
6,400원
6.
2000.06
구독 인증기관 무료, 개인회원 유료
Radio astronomy, on its part, requires 'quiet zones' to be able to receive incoming cosmic signals unaffected by interference to enable astronomers and others learn about universe. The agenda item 1.16 of WRC-2000 contains a number of issues relevant for radio astronomy, but some of them are more important than others. The preparations for WRC-2000 have reached a close-to-final stages, with a number of proposals to this agenda item submitted to the ITU by many countries and groups of countries, like APT, CEPT and CITEL. There is no clear preference to anyone of these proposals since their differences are only minor. However, several points remain to be solved in the APT and CITEL. Fortunately, the preparation went very well, and consensus was reached on allocations above 71 GHz and three resolutions. The radio astronomy has obtained about 100 GHz of new spectrum allocations in bands above 71 GHz. In addition, a new resolution was approved by plenary meeting of WRC-2000. It deals with the consideration by a future WRC of sharing and compatibility issues between passive and active services in adjacent bands particularly with the space services (downlinks) into radio astronomy above 71 GHz. Therefore, in future, there should be a need for studies to be made to determine if and under what conditions sharing is possible, given that modifications were made on the basis of requirements known now and that little was known of requirements and implementation plans for active services in bands above 71 GHz.
6,400원
