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 共查询到18条相似文献,搜索用时 93 毫秒
1.
何玉囡 《天文学报》1995,36(3):321-330
本文分析了傣历纪元纪时法中的一些基本算法,给出了计算闰月总数的修正公式,编制了计算傣历的程序,计算了傣历1283-1402年(公元1921-2040年)年历表,并对傣历与农历的月序比较提出了新看法。  相似文献   

2.
河外射电源在IERS综合表与观测表中坐标差的特性分析   总被引:1,自引:0,他引:1  
本文简要介绍了IERS综合河外射电源表在所用资料、建立方法等方面的一般情况,进而分析了河外射电源在IERS综合表与观测表中的坐标表的一般特性,为检验综合表提供了分析基础。  相似文献   

3.
本文简要介绍了IERS综合河外射电源表在所用资料、建立方法等方面的一般情况,进而分析了河外射电源在IERS综合表与观测表中的坐标差的一般特性,为检验综合表提供了分析基础。  相似文献   

4.
本文对IERS综合河外射电源表进行了检验,指出1988至1991各年度的IERS综合河外射电源表中均存在坐标系统不一致问题,部分射电源的位置坐标中带有几个毫角秒的偏差,与公认精度不符。坐标系统不一致问题影响了IERS综合表的指向维持,使此维持仅限于数学意义上的平均水平,失去了明确的物理意义。  相似文献   

5.
本文对IERS综合河外射电源表进行了检验,指出1988至1991各年度的IERS综合河外射电源表中均存在坐标系统不一致问题,部分射电源的位置坐标中带有几个毫角秒的偏差,与公认精度不符,坐标系统不一致问题影响了IERS综合表的指向维持,使此维持仅限于数学意义上的平均水平,失去了明确的物理意义。  相似文献   

6.
本文利用弧长差选源方法和共同基本源指向维持模型,并参照当今各河外射电源观测表之间的相互独立性,组建了1988至1993各年度的综合河外射电源表,即N-Cat系列综合表。检验结果表明,N-Cat系列表中坐标系是统一的,其指向维持精度高于0.1mas,明显好于A-Cat系列表和IERS系列表,这充分肯定了弧长差选源方法和共同基本源指向维持模型的优越性。文中部分结果显示,1992年与1993年的IERS综合表之间存在显著指向差异,对此应予以重视。  相似文献   

7.
该首先对公元九世纪初汉译佛经《七曜攘灾决》中的木星历表进行了释读,然后对木星历表中的留、伏、见等特征天象的时间和位置坐标进行了分析计算,并讨论了木星历表的编制精度。章最后进一步讨论了木星历表作为一份星占学手册在日本古代被星占家们使用的情况。  相似文献   

8.
利用北京天文台具有CCD终端的60cm光学望远镜观测射电源的光学对应体,得到了01716+714和0839+187精确的光位置。参考星表采用拉帕玛的18cm全自动子午环观测资料编制的CAMC星表,该星表是FK5星表系统。  相似文献   

9.
鉴于IERS综合河外射电源表在建立IAU协议天球参考架方面的重要意义和它们的不足之处,本文重新组建了1988至1992各年度的综合河外射电源表,称之为Cat系列表。并依据综合表的组建原理,对重新计算得到的Cat系列表进行了检验,结果表明Cat系列表克服了IERS系列表中坐标系不统一的缺点,指向的定义及维持亦较之IERS系列表有较大程度地改观。比较结果显示,IERS系列表中部分源的坐标存在毫角秒量级的偏差,各年度综合表的指向与IERS预期指向亦有不同程度的偏离,个别轴的最大指向偏差至0.6mas。同时指出,1993年IERS综合表的指向亦有待讨论。  相似文献   

10.
一种新的射电源表综合方法   总被引:1,自引:0,他引:1  
唐正宏  须同祺 《天文学报》1996,37(3):320-326
本文提出利用正交完备函数系拟合射电源表的局部系统差,并通过选择初始星表确定综合射电源表系统的轴方向,在综合计算时以射电源表包含的所有源坐标决定其轴方向.整个综合过程概念清晰,计算量较小.检验结果表明,用新方法得到的综合射电源表可靠性与稳定性都很好.  相似文献   

11.
The works of the Goloseevo Observatory (Kiev, U.S.S.R.) on the compilation of catalogues of absolute proper motions measured with respect to faint galaxies are discussed. Using these catalogues, some astrometric and stellar characteristics have been obtained. Particular attention is paid to the problem of improving the accuracy of stellar position and proper motion determinations. The optimum procedure for compiling the consolidated catalogue intended for the improvement of fundamental reference frame, kinematic characteristics of stars as well as for the solution of applied problems is developed.  相似文献   

12.
Interplanetary magnetic field data obtained from near-Earth spacecraft are used to compile a catalogue of high-velocity solar wind streams for the period June 1978 through October 1982 (Bartels rotations 1980–2039). The compilation of high-velocity streams is a continuation of two previous lists which covered the periods 1964–1975 and 1975–1978, respectively. The total number of high-speed solar wind streams listed in the catalogues is 637 of which 520 are corotating streams and 117 are classified as flare-associated streams.  相似文献   

13.
Observation catalogues of extragalactic radio sources obtained by Very long Baseline Interferometry during the last decade agree in the mean to a few milliarcseconds (mas). Within this range the position differences show constant, linear and periodic offsets. To reduce the influence of individual catalogue properties the construction of a compilation catalogue seems to be the appropriate procedure. In some detail the compilation method is described providing simultaneous adjustment of source positions and catalogue corrections. The compilation catalogue consists of 40 objects having positional errors of 0.2 mas in right ascension (RA) and 0.3 mas in declination (Dec). Comparing this catalogue with the IERS Celestial Reference Frame compiled by means of other precepts yields weighted root-mean-square differences of 0.7 mas in RA and 1.3 mas in Dec. Finally, the terms of general precession in RA and Dec are included in the adjustment process giving estimates of the correction to the luni-solar precession between –1 and –3 mas/yr, the latter figure applying when some early data are added.  相似文献   

14.
Gravitational lensing predicts an enhancement of the density of bright, distant quasi-stellar objects (QSOs) around foreground galaxies. We measure this QSO–galaxy correlation w qg for two complete samples of radio-loud quasars, the southern 1 Jy and half-Jansky samples. The existence of a positive correlation between     quasars and     galaxies is confirmed at a     per cent significance level (>99.9 per cent if previous measurements on the northern hemisphere are included). A comparison with the results obtained for incomplete quasar catalogues (e.g. the Veron-Cetty and Veron compilation) suggests the existence of an 'identification bias', which spuriously increases the estimated amplitude of w qg for incomplete samples. This effect may explain many of the surprisingly strong quasar–galaxy associations found in the literature. Nevertheless, the value of w qg that we measure in our complete catalogues is still considerably higher than the predictions from weak lensing. We consider two effects which could help to explain this discrepancy: galactic dust extinction and strong lensing.  相似文献   

15.
A reference catalogue of 373 well-defined high-speed plasma streams identified in the solar wind measurements from 1985 to 1996 is reported. The data base for this study is the interplanetary plasma/magnetic field data compilation made available by the NSSDC/WDC-A for rockets and satellites (NASA/GSFC-Greenbelt). The main characteristics of those streams, such as the beginning time, the duration, the origin of them (corotating or flare-generated), the interplanetary magnetic field polarity (Stanford magnetic field), are given in the catalogue.The long-term variation in the occurrence rate of high-speed streams shows interesting differences between even and odd solar cycles when catalogues for solar cycles 20, 21, and 22 are considered together. Hence, this catalogue, extended now over three solar cycles, should be useful for studies connected with solar-interplanetary or solar-terrestrial phenomena, and to clarify solar activity in time.  相似文献   

16.
One of the main problems of selenodesy consists of the construction of a net of basic reference points on the surface of the Moon. At present there exist many catalogues containing the coordinates of selected objects on the Moon. These catalogues differ by the presence of both systematic and accidental errors.The investigations concerning the comparison of catalogues and the elucidation of their systematic differences are of very recent date. Various methods of interpretation of the systematic differences between catalogues have been proposed. Without an attempt to encompass the whole problem in what follows, we shall describe one method for comparative study of catalogues based on the theory of the deformation of continuous media.  相似文献   

17.
天文数据主要包括星表、星图、光谱、文献资料等,其中星表是包含天体信息的数据表格,是天文学家最常用到的天文数据。目前天文数据分布存储在全球各个数据中心。中国最大的天文数据中心是北京天文数据中心,其数据库的重要部分是天文星表数据库。本文阐述了建设天文星表数据库的意义,着重探讨了星表自动入库工具的实现,并介绍了在天文星表数据库基础上的数据融合和数据挖掘。  相似文献   

18.
在过去的时间纬度工作中,对大气反常折射的研究证明,大气反常折射给时问纬度测量带来了严重的影响。而当时大多数星表的编制都是时间纬度测量的副产品,无疑大气反常折射也给这些星表带来严重的误差影响。过去我国的经典天体测量工作以测时、测纬为主,这一问题并没有得到重视。在星表和参考系工作已成为我国基本天休测量工作的一项主要内容的今天,对大气反常折射的测量与研究,尤其对有效的测量应得到足够的重视。作者根据自己的实际测量和研究指出,大气反常折射主要由观测室周围不良小气候的造成,其中以具有周年变化和周日变化的大气反常折射对初始星表系统的影响最为严重。并分别讨论了这种反常折射对子午星表、等高星表和参考系的影响,提出了今后开展这方面工作的建议。  相似文献   

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