低纬子午环配备科学CCD后的课题目标

本文根据基本天体测量的主要任务和目前发展趋势的要求,以及低纬子午环配备ＣＣＤ后的观测精度、效率和极限星等,提出了该仪器长期观测;的目标,包括建立实用的准惯性天球参考架和动力学参考架,为太阳系动力学研究,为银河系结构和运动学研究,为某些天体物理课题研究的需要,提供有用的观测数据,为本地的地震预报和天文地震研究提供参考数据。在甚长基线射电干涉测量技术和空间测量技术迅速发展的时代,地面光学天体测量仍具有     

低纬子午环配备科学CCD后的课题目标

针对低纬子午环配备科学ＣＣＤ后的观测能力，叙述了该仪器观测的课题目标：为建立准惯性天球参考架提供充分的观测数据，为建立动力学参考架和太阳系动力学研究提供天然卫星和小行星的高精度数据，为银河系结构和运动学研究提供必要的数据，为某些天体物理课题研究提供有用的数据，为地球动力学和天文地震研究提供基本的测量数据。将来编制观测纲要时，会兼顾到这些方面的需要，合理安排，以求充分发挥该仪器的作用。     

依巴谷后的天体测量卫星项目——空间光干涉卫星

简述了依巴谷后提出的天体测量卫星项目,如FAME、DIVA、JASMINE、SIM Lite、Gaia、OBSS、JMAPS等。描述了空间光干涉从1980年至今的发展过程,特别给出了用天体测量方法研究天体物理课题之SIM Lite工程的近况:科学目标、仪器的结构、技术上的重大突破点和观测方式等。重点介绍了SIM Lite参考架的构建,包括栅格星和类星体的选择,以及SIM Lite光学参考架与射电参考架ICRF-2之间的联系和联系的精度。比较了SIM与Gaia观测方式的不同点,以及它们在天体物理研究和参考架的建立上互补之处。最后,回顾了中国科学院"八五"重点项目"光学天文中高空间分辨率应用和技术研究"和当前开展有关光干涉工作的一些情况,以及今后开展此课题的若干建议。     

低纬子午环的总体设计要求

根据地面光学天体测量发展的需要和低纬子午环课题目标的要求，叙述了该仪器的总体设计要求和提出这些要求的理由，强调指出了如何高精度地测定仪器的制造误差、安装误差和重力变形、热变形的影响，以及如何消除测量仪器误差的各设备的零点偏差及其漂移的影响，以便保持仪器观测系统的长期稳定性。     

研制低纬子午环初衷的沿革

介绍了在低纬子午环研制过程中，如何跟踪国内外测量方法和科学技术的发展，调整该仪器的主要课题目标：开始时仅计划在低纬度地区进行天体位置的绝对测定，改善基本星表系统；在１ｍ望远镜试验ＣＣＤ底片重迭法成功后，打算把该仪器绝对测定的恒星位置与河外天体联系起来，间接地建立准惯性天球参考架；当国外传统子午环配备ＣＣＤ测微器作相对测量后，提出了在该仪器上配备ＣＣＤ测微器作绝对测定的方法，用其观测数据直接建立实用的准惯性天球参考架，并为太阳系和银河系研究提供有用数据的总体目标。     

GAIA计划与微角秒天体测量学

欧洲空间局正在考虑的空间天体测量卫星计划（GAIA计划）将对目视星等V亮于15．5mag的5千万颗目标进行位置、自行和视差的测定,其精度为10μas,同时还对这些目标进行多色多历元光度测定．该计划可对星系距离尺度、恒星演化、银河系运动学和动力学以及参考架联结等方面进行深入研究．其开创的微角秒天体测量学亦将会对天体物理学、太阳系天体和参考架联结等方面的研究产生深远的影响．     

中国与丹麦合作的水平子午环在建立惯性坐标系中的作用

预计Hipparcos测定星位的精度要远好于地面仪器的结果。对于从事地面仪器测量的天体测量学家来说,必须回答:地面仪器还能发挥什么作用?我们认为,地面仪器在未来建立惯性坐标系中仍起着重大作用。因为:1.地面经典仪器有相当长的观测历史,因此,在自行方面,有较好地面仪器观测历史的天体其精度并不亚于Hipparcos的结果。2.地面仪器观测可研究与地球物理有关的问题.3.空间卫星不可能包罗全部课题,仍有大量的课题需要地面仪器去观测。4.地面仪器研究课题的运转周期短。一般来说,空间观测的课题要10年以上的周期。5.地面仪器的改造,使得效率和精度有相当大的提高,特别是CCD探测器在天体测量上的应用。中国与丹麦合作的水平子午环,其有效口径为240mm,可观测到13~m.5的天体,因此我们的仪器将在惯性坐标的建立中发挥作用。根据本仪器的特点,可在下列课题发挥其作用:1.观测射电星,作参考系联结的工作。2.观测较暗的小行星,进行坐标系分点改正的工作。3.进行IRS星的绝对测定。4.观测射电源周围的天体,作为观测射电源的定标垦。5.改进FK5星的位置精度。本文发表于IAU141讨论会,1989年10月,列宁格勒。     

空间时代地面光学天体测量的意义

从基本天体测量的主要任务出发，介绍了绝对测定和相对测量之间的区别和不同用途，并针对河外射电源参考架和依巴谷参考架的高精度的不足之处，说明了地面光学天体测量的长期性和灵活性等优势正是克服这些不足之处所必须的，但这不应是传统的已有精度下的地面光学天体测量，而应是与空间测量精度可比的要求下的地面测量，两者配合起来，将能促进本学科和相关学科的发展。     

未来的国际天球参考架

本文简述了国际天球参考架的发展历史和现在射电参考架的现状—基准源选择的标准和参考架的稳定性。描述了地面上光学观测在依巴谷参考架的维持和加密的一系列工作。介绍由天体测量卫星GAIA和SIM给出的天球参考架可能逵到的精度。详述了在今后十年中地面天体测量的作用以及正在开展有关天球参考架的研究课题 ,同时也列出了我国正在和即将开展天体测量的几个研究课题     

低纬子午环配备CCD探测器(Ⅰ)——观测原理

这一组文章,从观测原理、各种仪器常数和误差测定方法的叙述到测定精度的估计,系统地论述了在低纬子午环上配备CCD探测器后将能达到的绝对定位精度及其对建立高精度天球参考架的作用。文章(Ⅰ)中简述了充分发挥地面观测优势的途径,低纬子午环配备CCD探测器后的观测方式、星过时刻和天顶距的计算公式,还估算了在小角天体测量中相对位置的测定精度,并且得出,采用了CCD探测器后,降低了对测微器的跟踪精度要求。     

Third Integral and the Dynamics of the Galaxy in the Neighborhood of the Sun

Observational data on the dynamics of stars in the neighborhood of the sun indicate the existence of a third integral besides the integrals of the angular momentum and energy. The Poincaré integral is proposed as a third integral. The consequences of this assumption are derived and compared with available astrophysical data.     

耀变体亮温度与黑洞喷流能量的相关性讨论

耀变体(Blazars)的亮温度与黑洞喷流能量和吸积率有重要关系.搜集了53个耀变体源样本,包括22个蝎虎天体(BL Lacs)和31个平谱射电类星体(Flat Spectrum Radio Quasars,FSRQs),研究了耀变体亮温度与黑洞喷流能量的分布,并对子类中亮温度与黑洞喷流能量的相关性进行了讨论.研究结果...     

在后牛顿引力理论(PPN形式)中引力常数变化对地球自转产生的效应

介绍和论述了在后牛顿引力理论(PPN形式)中在优越参考系和非优越参考系中经过参数化后引力常数变化对地球自转产生的效应,其中特别重点介绍了年周期变化的效应。此外也将理论结果同观测结果相对比。     

Impact of the Quadrupole Moment of the Sun on the Dynamics of the Earth-Moon System

Range of values of the Sun's mass quadrupole moment of coefficient J₂ arising both from experimental and theoretical determinations enlarge across literature on two orders of magnitude, from around 10^-7 until to 10^-5. The accurate knowledge of the Moon's physical librations, for which the Lunar Laser Ranging data reach an outstanding precision level, prove to be appropriate to reduce the interval of J₂ values by giving an upper bound of J₂. A solar quadrupole moment as high as 1.1 10^-5 given either from the upper bounds of the error bars of the observations, or from the Roche's theory, is not compatible with the knowledge of the lunar librations accurately modeled and observed with the LLR experiment. The suitable values of J₂ have to be smaller than 3.0 10^-6. As a consequence, this upper bound of 3.0 10^-6 is accepted to study the impact of the Sun's quadrupole moment of mass on the dynamics of the Earth-Moon system. Such as effect (with J₂ = 5.5±1.3 × 10^-6) has been already tested in 1983 by Campbell & Moffat using analytical approximate equations, and thus for the orbits of Mercury, Venus, the Earth and Icarus. The approximate equations are no longer sufficient compared with present observational data and exact equations are required. As if to compute the effect on the lunar librations, we have used our BJV relativistic model of solar system integration including the spin-orbit coupled motion of the Moon. The model is solved by numerical integration. The BJV model stems from general relativity by using the DSX formalism for purposes of celestial mechanics when it is about to deal with a system of n extended, weakly self-gravitating, rotating and deformable bodies in mutual interactions. The resulting effects on the orbital elements of the Earth have been computed and plotted over 160 and 1600 years. The impact of the quadrupole moment of the Sun on the Earth's orbital motion is mainly characterized by variations of , , and . As a consequence, the Sun's quadrupole moment of mass could play a sensible role over long time periods of integration of solar system models. This revised version was published online in July 2006 with corrections to the Cover Date.     

On the planetary acceleration and the rotation of the Earth

We have developed a cosmological model for the Earth rotation and planetary acceleration that gives a good account (data) of the Earth astronomical parameters. These data can be compared with the ones obtained using space-base telescopes. The expansion of the universe has shown to have an impact on the rotation of planets, and in particular, the Earth. The expansion of the universe causes an acceleration that is exhibited by all planets.     

On the design of the PEPSI spectropolarimeter for the LBT

We present the design concept of the spectropolarimeter for the high‐resolution echelle spectrograph PEPSI tobe installed at the 2 × 8.4 m Large Binocular Telescope (LBT) in Arizona. We discuss the optical key elements, the principles of operations of the instrument and its instrumental polarization effects (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

On the role of the motion of the photospheric footpoints of the magnetic field lines

By means of a simple relation between the velocity v of the fluid particle and the velocity v_f of the photospheric footpoint of the magnetic field line v_z and B_z being respectively the components of v and the magnetic field B normal to the photospheric surface, it is shown formally that through the phtospheric surface the transport of all the quantities attributed to the magnetic field, such as the magnetic flux, the magnetic energy and the helicity, is independent of v_z, and v_f is the only kinematical quantity on which the transport depends. In addition, in the neighborhood of the neutral line the velocity v_l of the moving curve of constant B_z is found to be equal approximately to the component of v or v_f in the direction of v_l. Since v_l can be measured or extimated, so can the components of v and v_f near the neutral line.     

On the origin of the solar system and the exceptional position of the Sun in the Galaxy

The solar system's position in the Galaxy is an exclusive one, since the Sun is close to the corotation circle, which is the place where the angular velocity of the galactic differential rotation is equal to that of density waves displaying as spiral arms. Each galaxy contains only one corotation circle; therefore, it is an exceptional place. In the Galaxy, the deviation of the Sun from the corotation is very small — it is equal to ΔR/R _⊙≈0.03, where ΔR=R _c ?R _⊙,R _c is the corotation distance from the galactic center andR _⊙ is the Sun's distance from the galactic center. The special conditions of the Sun's position in the Galaxy explain the origin of the fundamental cosmogony timescalesT ₁≈4.6×10⁹ yr,T ₂?10⁸ yr,T ₃?10⁶ yr detected by the radioactive decay of various nuclides. The timescaleT ₁ (the solar system's ‘lifetime’) is the protosolar cloud lifetime in a space between the galactic spiral arms. The timescaleT ₂ is the presolar cloud lifetime in a spiral arm.T ₃ is a timescale of hydrodynamical processes of a cloud-wave interaction. The possibility of the natural explanation of the cosmogony timescales by the unified process (on condition that the Sun is near the state of corotation) can become an argument in favour of the fact that the nearness to the corotation is necessary for the formation of systems similar to the Solar system. If the special position of the Sun is not incidental, then the corotation circles of our Galaxy, as well as those of other galaxies, are just regions where situations similar to ours are likely to be found.     

Perturbations by the oblateness of the Earth and by the planets in the motion of the Moon

Perturbations in the motion of the Moon are computed for the effect by the oblateness of the Earth and for the indirect effect of planets. Based on Delaunay's analytical solution of the main problem, the computations are performed by a method of Fourier series operation. The effect of the oblateness of the Earth is obtained to the second order, partly adopting an analytical evaluation. Both in longitude and latitude are found a few terms whose coefficient differs from the current lunar ephemeris based on Brown's theory by about 0.01. While, concerning the indirect effect of planets, several periodic terms in the current ephemeris seem to have errors reaching 0.05.As for the secular variations of and due to the figure of the Earth and the indirect effect of planets, the newly-computed values agree within 1/cy with Brown's results reduced to the same values of the parameters. Further, the accelerations in the mean longitude, and caused by the secular changes in the eccentricity of the Earth's orbite and in the obliquity of the ecliptic are obtained. The comparison with Brown shows an agreement within 0.3/cy² for the former cause and 0.02/cy² for the latter. An error is found in the argument of the principal term for the perturbations due to the ecliptic motion in the current ephemeris.Proceedings of the Conference on Analytical Methods and Ephemerides: Theory and Observations of the Moon and Planets. Facultés universitaires Notre Dame de la Paix, Namur, Belgium, 28–31 July, 1980.