天文常数研究的进展——IAU 2009天文常数系统

回顾了1900年以来LAU采用天文常数系统的简况,以及一些天文常数之间的数学关系,并描述了以前每次改变天文常数系统的主要因为.介绍了1991年以来IAU在天文常数方面的工作:包括IAU天文常数工作组和天文常数最佳估计值的情况.叙述了IAU 2009年天文常数系统替代IAU 1976天文常数系统的因为:随着人类对太阳系的探测,获得新的天文常数测定值;1991年以来在相对论框架下BCRS和GCRS的使用;P03岁差模型和MHB2000章动模型的采用.比较了IAU2009和1976天文常数系统的差异.最后介绍中国在天文常数方面工作的情况和今后工作的建议.     

天文常数中的相对论问题

现代天文观测技术的日新月异、广义相对论的１ＰＮ近似方法在天体力学和天体测量中的广泛应用,使得有必要在１ＰＮ框架中严格而细致地重新审查天文常数系统。在相对论框架里,太阳系天体的质量应当定义为ＢＤ质量,它们的相对变化不超过１０＾－１９,可视为守恒量;引力势满足的方程不再是Ｐｏｉｓｓｏｎ方程而与坐标规范的选择有关,引力势也不再能用传统的球谐函数展开。应当选定一种规范,并且以ＢＤ多极矩作为天文常数。黄赤交     

主章动常数和对它的天文实测

本文列举了最近以来,光学天文、VLBI和LLR等技术对主章动常数的测量结果,结果表明对国际天文学联合会(IAU)在1982年通过的1980 IAU章动理论应予以修正。文中强调了现代天文实测工作应该在地球模型和章动理论的研究中起到更大的作用;还讨论了在实际进行主章动常数测量工作时应该注意的一些问题。     

中国开展的星表和天文常数研究活动(1990.7～1993.1)

叙述了1990年7月至1993年1月期间中国的星表和天文常数工作。它包括仪器的改进与研制,星表的观测和编算,天文常效、天球参考系的研究,以及其相应的方法与技术.     

新天文常数系统

归算观测所必需的一系列参数的采用值,定义为一个天文常数系统,它应当是一个自洽的参数序列,即常数间严格满足已知的理论关系。至今,国际上曾采用过三个天文常数系统。 1.第一个常数系统主要是由纽康的数值组成的,它被采用了半个多世纪。 2.IAU(1964)天文常数系统,从1968年起被引用。 3.IAU(1976)天文常数系统,称为新天文常数系统,已被1976年格勒诺布尔国际天文学联合会大会所采用。新系统将从1984年起取代1964年采用的系统。 本文详细说明了习用的天文常数系统的变化,并描述了新天文常数系统的特征。     

刚体地球章动理论

介绍和比较最新的刚体地球章动理论，重点评述可能成为未来ＩＡＵ章动系列基础的ＫＳ９０理论，它考虑了力学因素，采用的历表和常数系统，对现行Ｋ７７理论的改进，同时也指出了ＫＳ９０应作了微小修正。     

大气湍流理论的进展及其天文学意义

传统的大气湍流理论始于大约３０年前。湍流理论的发展使得天文学家对大气湍流对天文观测的影响有了很好的认识，尤其是它为天文台选址和天文高分辨率技术提供了基础。近年来新的天文观测对已传统的大气湍流理论提出了挑战，并可能给地面天文观测带来一场革命。在回顾了大气湍流理论的发展历史后对传统大气湍流理论的基本特性及其应用作了系统的综述，并介绍了新的天文观测事实以及为此而提出的新的大气湍流理论模型。     

《天文爱好者》1996年总目录

《天文爱好者》１９９６年总目录高能中微子天文学简介１∶１９一年之内三大天象奇观─—百武彗星、海尔－波普彗星和日全食３∶２空间天文发展的现状与展望４∶２齐心协力研天象─—ＩＡＵ历史回顾４∶８中国空间科学发展的现状和趋势５∶１７本刊特稿ＬＡＭＯＳＴ之旅太...     

计算机打印口用作天文仪器接口

目前基本上所有天文仪器都是数字化的，几乎所有天文设备与计算机都有接口问题。我们在多套系统中采用计算机打印口来控制天文终端，认为这样做有不少好处。本文介绍了利用打印机接口天文仪器控制的技术，并给出两个例子。     

小型激光天文动力学空间计划概念

小型激光天文动力学空间计划是 :使用在太阳轨道上无拖曳航天器和地面站以激光干涉和脉冲测距的方法 ,精确地探讨天文动力学 ,检测相对论与时空基本定律 ,改进探测引力波的灵敏度以及更准确地测定太阳、行星和小行星的参数。 1 969年开始的月球激光 (反射 )测距 ,对地球物理、参考坐标的选定、相对论的检验均有重要的贡献。 3 0年来 ,激光技术的长足进步 ,使现在正是适合于开始进行研究空间有源 (主动 )测距和光波空间通讯的时候。激光天文动力学的兴起是必然的趋势 ,其精确度将比现在提高 3到 6个数量级 ,将是天文动力学革命性的发展。小型激光天文动力学空间计划可以起到带头作用。它的关键技术有三 ,即 :弱光锁相、极精确无拖曳航天和高衰减日冕仪。弱光锁相已有长足的进步。对高衰减日冕仪的研究 ,也有了初步的方案。LISA空间计划将于 2 0 0 6年 8月发射SMART -2 ,研究测试极精确无拖曳航天。小型激光天文动力学空间计划的关键技术已日趋成熟。在第一届国际激光天文动力学研讨会 ( 2 0 0 1 ,9.1 3 -2 3 )中介绍了各相关学科背景及前沿研究 ,讨论了激光天文动力学空间计划科学目标及相关技术 ,并召开了两次小型激光天文动力学空间计划预研究筹备会 ,建立了和欧洲的合作关系。会后着手进行此项对基础     

On the precession expressions based on the de ephemeris

Since 1984, the new IAU (1976) System of Astronomical Constants has become effective; meanwhile, the new lunar and planetary ephemerides (DE200/LE200) have been introduced into the Astronomical Almanac. In order to obtain the best fit of these ephemerides to the observational data, some modifications to the constants were made (Kaplan 1961). The modified values of these constants have been accepted by many users (particularly in the Merit Project), (Melbourne et al. 1983), although there has not been any new resolution of IAU. To avoid these inconsistencies, it seems to be necessary to rediscuss the adopted value of some astronomical constants in the new system. This paper discusses the problems for selection of the precession quantities and derives the precession expressions based on the motion of ecliptic from the DE ephemeris.     

A system of astronomical constants in the relativistic framework

The relation between the units and readings of time and space coordinates of terrestrial and barycentric reference frames is discussed from the viewpoint of general relativity. Attention is paid to the unit of space coordinates since the International Astronomical Union (IAU) regulates only the unit of time in the above two frames. Two definitions of unit of length are examined and their effects on the numerical expression of coordinate transformation, equations of planetary motions, and those for light propagation time are discussed. A clear conflict is found between the IAU (1976) recommendation on the definition of the time-scales in different frames of reference and the statement that all constants in the IAU (1976) new system of astronomical constants are defined in terms of the Internationsl System of units (SI units). One of the above two definitions is proposed to resolve this conflict by the least alteration to current procedures for analysing the recent astrometric observations such as the radar/laser rangings, the range and range-rate, and the very long baseline interferometric observations. Also, an interpretation of numerical values in the IAU (1976) new system of astronomical constants is presented. It is stressed that the definition proposed in this paper requires that a formula slightly different from that in current use be employed in the numerical transformation of readings of coordinates between the terrestrial and barycentric reference frames.     

The IAU 2009 system of astronomical constants: the report of the IAU working group on numerical standards for Fundamental Astronomy

In the 2006?C2009 triennium, the International Astronomical Union (IAU) Working Group on Numerical Standards for Fundamental Astronomy determined a list of Current Best Estimates (CBEs). The IAU 2009 Resolution B2 adopted these CBEs as the IAU (2009) System of Astronomical Constants. Additional work continues to define the process of updating the CBEs and creating a standard electronic document.     

Fundamental catalogues,past, present and future

Presented is a review of the main achievements of fundamental astrometry from earliest times through the present century. At all times the construction of a celestial reference coordinate system has tormed an important task for describing motions in the sky. The positions of fundamental stars and their centennial variations have been laid down in fundamental catalogues which-beginning with the 18th century-have facilitated famous discoveries and have given rise to the improvement of the techniques of observation. This review culminates in the documentation of the observational achievements of the latest 25 years where in a world-wide campaign of about 50 observatories considerable contributions have been made to the improvement of the current conventional reference coordinate system given in the Fourth Fundamental Catalogue (FK4). The observations analysed in an ambitious program at Heidelberg will yield the FK5 which also will introduce the System of Astronomical Constants adopted by the IAU in 1976. This report ends with an outlook on contributions of space techniques and of radioastrometry of extragalactic sources to progress in fundamental astrometry.Dedication: This review is an extended version of the Dirk Brouwer Lecture 1983 of the Division on Dynamical Astronomy of the American Astronomical Society. With the topics of this lecture the author honors Dirk Brouwer's contributions to astrometry and gratefully acknowledges the support given to astronomy by Ministerialdirigent Karl Otto Schlau in the Government of Baden-Württemberg, Stuttgart, Federal Republic of Germany.     

Simultaneous solution for the masses of the principal planets from analysis of optical,radar, and radio tracking data

The Jet Propulsion Laboratory has developed a set of computer programs known as the Solar System Data Processing System (SSDPS) which is employed in improving the ephemerides of the major planets and for improving the values of several associated astronomical constants. A group of solutions for the masses of the major planets, together with the AU and radii of Mercury, Venus, and Mars, is presented. These solutions based upon optical, radar, and spacecraft radio tracking data are preliminary. The relative power of radar and radio tracking data vis-à-vis purely optical data in a solution is shown. The problems which could arise by adopting solutions based upon a single data type are demonstrated.Presented at IAU Colloquium No. 9, the IAU System of Astronomical Constants' Heidelberg, Germany, August 12–14, 1970.This paper presents the results of one phase of research carried out at the Jet Propulsion Laboratory, California Institute of Technology, under Contract No. NAS 7-100, sponsored by the National Aeronautics and Space Administration.     

Precise positions of optical counterparts of some radio objects

We present optical positions in the improved IAU System at the standard epoch J2000.0 of some extragalactic radio sources obtained at Torino Astronomical Observatory. The primary reference stars are taken from the Carlsberg Automatic Meridian Catalogues 1 and 2 (CAMC).     

Determinations of precession

Recent determinations of lunisolar precession and of the motion of the equinox are reviewed. Methods of determination are discussed which are based on proper motions referred to fundamental systems, on planetary motions, and on proper motions referred to galaxies. It is concluded that a new fundamental catalogue, which will replace the FK4 at some future date, should be based on revised values of precession and freed from errors in the motion of the equinox.Presented at IAU Colloquium No. 9, The IAU System of Astronomical Constants, Heidelberg, Germany, August 12–14, 1970.     

Détermination des masses des planétes

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Presented at IAU Colloquium No. 9, The IAU System of Astronomical Constants', Heidelberg, Germany, August 12–14, 1970.