我看到了水星凌日

我看到了水星凌日水星凌日是水星经过日面的天文现象，平均每一百年发生十三次。本世纪最后两次水星凌日是在１９９３年１１月６日和１９９９年１１月１５日发生。１１月３日，我收到载有水星凌日资料的《业余天文快讯》，并参考《天文爱好者》和《天文普及年历》，计算了...     

第十三届国际天文奥林匹克竞赛实测试题

高年组： 一、系外行星凌星。探测系外行星的最可靠方法之一,就是观测行星凌恒星现象。当凌星发生时,由于行星遮挡在恒星之前,恒星的辐射流量F会从正常的F0暂时性地下降。     

水（金）星凌日的程序化预报方法

本文介绍了预报水(金)星凌日的计算方法和凌日图的绘制方法,建立了一套完整的预报程序。作为该程序的一个简单应用,我们结合DE200历表及美国海军天文台提供的岁差章动程序,给出了1999年水星凌日的预报结果。     

西宁城中区少儿科教中心组织观测水星凌日

西宁城中区少儿科教中心组织观测水星凌日１９９３年１１月６日上午，青海省西宁市城中区少儿科教中心组织解放路小学天文小组部分同学在乐家湾旧飞机场草坪成功地观测到了一次罕见的水星凌日现象，并对水星凌日的重要天象进行了描图和照相观测。１１月６日上午９时３０分...     

M_f和M_m波固体潮Love数k_2的确定——来自空间大地测量的结果

初步探讨用日长和卫星轨道摄动方法研究半月潮Mf 和月潮Mm 的Love数k2 .结果表明 ,日长方法给出k2 =0 .30 32 i0 .0 0 2 8(Mf) ,0 .30 2 6 i0 .0 0 1 2 (Mm) ,卫星轨道摄动方法为k2 =0 .30 83-i0 .0 1 0 0 (Mf) ,0 .30 1 4-i0 .0 0 1 0 (Mm) ,并与理论固体潮计算结果较为相符 .另外 ,上述结果更接近滞弹地球模型计算的结果 ,因此精确地测定长期潮Love数将对固体潮理论和地幔滞弹性提供重要的结束 .     

区域GPS网实时计算可降水量的若干问题

目前地基GPS气象学测得的可降水量 (PWV )精度好于 2mm ,但在利用区域GPS网实时计算每个测站上空的PWV时 ,要涉及到很多常规GPS资料处理时所忽略的问题 ,如需考虑数据处理软件和计算方式的选择、站坐标的确定和约束、轨道的使用方法、网外辅助站最佳数量的确定、海潮对实时计算PWV的影响以及实时应用于气象服务时的端部效应等问题。利用上海GPS综合应用网获取的 2 0 0 2年 6、7月份长江三角洲地区入梅前后的数据 ,分析了利用区域性的GPS网实时计算高精度的PWV时要解决的各种问题 ,探讨了其数据处理方案     

《21世纪百年历》

中国科学院紫金山天文台编　上海辞书出版社1 999年 1 2月出版　大 32开 32 0页　定价 1 5元　　由中国科学院紫金山天文台编算 ,上海辞书出版社出版的《2 1世纪百年历》问世了。这本历书由历表和文字资料两大部分组成。历表给出 2 0 0 0年～ 2 1 0 0年共 1 0 1年的日历表 ,表中包含公历、夏历、星期、干支对照、节气、梅、伏和九九的日期 ,其中前 50年节气的交节时刻给到小时。历表采用最新太阳、月球运动理论计算按东经 1 2 0°标准时 (北京时 )为准。此书文字资料部分由上海天文台和上海市气象局专家编写。内容包括历和时间、气象知识和…     

系系外行星系统HAT-P-36的测测光观测研究

在2012至2014年期间,用云南天文台1 m望远镜对HAT-P-36系外行星系统的3次凌食事件进行了测光观测。用IRAF软件包对CCD测光图像进行处理,用coarse de-correlation和SYSREM方法对数据中的系统误差进行改正,最后用MCMC方法求解HAT-P-36行星系统的物理参数。新得到的行星质量比Mancini等人和Bakos等人的计算结果略微偏大。基于20组凌食事件的中心时刻数据,用最小二乘法对其进行拟合,得到更加精确的行星轨道周期(1.327 347 04±0.000 000 27)d,从O–C图中可以看出线性关系并不能很好地拟合数据点,但是功率谱分析没有发现明显的周期性信号,在此假设HAT-P-36b的轨道外存在一颗微扰行星并限定它的一些物理参数。     

利用非差资料的精密点定位方案

单站精密定位 (PrecisePointPositioning ,以下简称PPP)是在同时固定GPS精密星历和卫星钟的前提下 ,利用载波相位和伪距资料进行单台站的精密点定位 .采用该方法时不同台站之间不存在共同的待估参数 ,即各台站互不相关 ,这一特点大大降低了计算量 .采用美国喷气推进实验室JPL发展的数据处理软件GIPSY处理APSG联测资料 ,计算表明PPP的重复率相当于目前国内普遍采用的双差解算结果 .采用较好保持地面网构型的无基准算法 ,计算表明通过Helmert参考系转换后 ,PPP的解算结果与双差算法的外符精度大致相当 .解算表明 ,采用PPP处理 1 0 0个台站约需 3 .5小时 ,而处理同样的资料采用双差算法则需 1 8～2 0小时 .对于我国即将建成的大科学工程或地震监测的多达 2 0 0 0个接收机的GPS网而言 ,在保持精度前提下的节省计算资源和计算时间的PPP解算方案值得广泛的应用     

正在形成恒星的孤立分子云核物理性质的观测研究

利用青海站13．7m毫米波望远镜对从Spitzer的c2d项目样本中挑选出来的11个内部有恒星正在形成的孤立分子云核进行了13CO(J=1-0)、13CO(J=1-0)和C18O(J=1-0)的同时成图观测．对这些分子云核均观测到13CO(J=1-0)峰值强度极大值的一半处．计算了分子云核的密度和质量,得到维里质量(MVIR)与LTE质量(MLTE)之比13CO(J=1-0)为0．85±0．40,C18O(J=1-0)为0．77±0．35．同时计算了云核的密度轮廓．     

Precision of the ephemerides of outer planetary satellites

Ephemerides of planetary satellites are needed to address many problems. These ephemerides are used for subsequent observations. A comparison of the available ephemerides with new observations allows the accuracy of the former to be assessed. However, the precision of the ephemerides must be known a priori when solving the tasks. In this paper we formulate and solve the problem of estimating the precision of the ephemerides of outer planetary satellites derived from observations when applied up to the future moments.The methods of assessing the precision of ephemerides involve producing a set of samples of the same ephemeris inferred from observations with different samples of Monte Carlo generated random errors (RO) superimposed onto it. The statistical parameters of simulated observational errors are based on the results of the reduction of real satellite observations. We compute the deviations of the samples of the ephemeris from the standard ephemeris inferred from real observations and adopt the root-mean-square deviation of the apparent coordinates as the precision of the ephemeris. We also use alternative methods: one based on the matrix of covariances of parameter errors (RP), and another one based on bootstrap samples of observations (BS).We use three methods (RO, RP, and BS) to estimate the precision of the ephemerides of all the 107 outer planetary satellites over the 2010-2020 time interval. The precision of the ephemerides of different satellites varies from 0.05 to 4.0 arcsec. For a number of satellites new observations are of vital importance for maintaining the precision of the ephemerides at a level that would allow identification of satellites during the reduction of observations. For some satellites the precision of their ephemerides is of the order of the sizes of their orbits and such satellites can be considered to have been lost. We show that the method of bootstrap samples (BS) can give doubtful results in the cases where there are few observations, which covered a time interval that is shorter than the orbital period of the satellite.Our results suggest obtaining more precise ephemeris making new observations at the times of maximum estimated errors of the ephemeris.All the inferred estimates of the precision of ephemerides are available from the MULTI-SAT ephemeris server: www.imcce.fr/sat (IMCCE), www.sai.msu.ru/neb/nss/index.htm (SAI).     

A theory of integration for the extended Delaunay method

In this paper a method for the integration of the equations of the extended Delaunay method is proposed. It is based on the equations of the characteristic curves associated with the partial differential equation of Delaunay-Poincaré. The use of the method of characteristics changes the partial differential equation for higher order approximations into a system of ordinary differential equations. The independent variable of the equations of the characteristics is used instead of the angular variables of the Jacobian methods and the averaging principle of Hori is applied to solve the equations for higher orders. It is well known that Jacobian methods applied to resonant problems generally lead to the singularity of Poincaré. In the ideal resonance problem, this singularity appears when higher order approximations of the librational motion are considered. The singularity of Poincaré is non-essential and is caused by the choice of the critical arguments as integration variables. The use of the independent variable of the equation of the characteristics in the place of the critical angles eliminates the singularity of Poincaré.     

The solution of Jacobi's virial equation for celestial bodies

A relationship between the potential energy and the moment of the inertia for celestial bodies is heuristically discovered. This relationship consists in the constancy of the product of formfactors for the potential energy and the moment of the inertia. The product is independent of the body mass and its radial mass distribution.We find the exact solution of Jacobi's virial equation for a gravitating spherical body based on the relationship obtained. This solution represents the unharmonic radial oscillations of the body. The solution is valid for a wide class of celestial bodies including variable stars and relativistic objects for which a relativistic analog of Jacob's equation is derived.The period of the radial oscillations of the planets is estimated with the help of the solution found. We note the coincidence of the experimental data and our theoretical calculations for the Sun.We show the important role of the Coulomb forces in the formation of the planets. It is demonstrated that the Coulomb forces result in the relation between the planet masses and their average molecular weight.     

The 1997 Campaign of Observations of Mutual Occultations and Eclipses in the System of Jupiter's Galilean Satellites: Final Results

This paper presents the final results of the campaign of photometric observations of the Galilean satellites of Jupiter at the time of their mutual occultations and eclipses at the epoch of 1997 at observatories of Kazakhstan, Russia, and Ukraine. These results essentially contribute to the worldwide database of this type. They will help to refine the models of motion of the Galilean satellites of Jupiter. A comparison is made of the obtained data with the results of the worldwide campaign of observations of mutual occultations and eclipses in 1997. From the results of these observations, the differences of planetocentric coordinates of two satellites are calculated for a sequence of instants of time. Processing is based on the theory and the model of mutual occultations and eclipses of natural planetary satellites, which were developed by one of the authors in previous papers (Emel'yanov, 1999, 2000). In this paper, some new elements of the technique were used. We estimated the accuracy of observations. The paper contains information on the observing conditions and describes briefly the instruments employed.     

Two-integral distribution functions for axisymmetric systems

Some formulae are presented for finding two-integral distribution functions (DFs) which depend only on the two classical integrals of the energy and the magnitude of the angular momentum with respect to the axis of symmetry for stellar systems with known axisymmetric densities. They come from a combination of the ideas of Eddington and Fricke and they are also an extension of those shown by Jiang and Ossipkov for finding anisotropic DFs for spherical galaxies. The density of the system is required to be expressed as a sum of products of functions of the potential and of the radial coordinate. The solution corresponding to this type of density is in turn a sum of products of functions of the energy and of the magnitude of the angular momentum about the axis of symmetry. The product of the density and its radial velocity dispersion can be also expressed as a sum of products of functions of the potential and of the radial coordinate. It can be further known that the density multiplied by its rotational velocity dispersion is equal to a sum of products of functions of the potential and of the radial coordinate minus the product of the density and the square of its mean rotational velocity. These formulae can be applied to the Binney and the Lynden-Bell models. An infinity of the odd DFs for the Binney model can be also found under the assumption of the laws of the rotational velocity.     

Solar oscillations and the equation of state

Summary Accurate measurements of observed frequencies of solar oscillations are providing a wealth of data on the properties of the solar interior. The frequencies depend on solar structure, and on the properties of the plasma in the Sun. Here we consider in particular the dependence on the thermodynamic state. From an analysis of the equations of stellar structure, and the relevant aspects of the properties of the oscillations, we argue that in the convection zone one can isolate information about the equation of state which is relatively unaffected by other uncertainties in the physics of the solar interior. We review the different treatments that have been used to describe the thermodynamics of stellar plasmas. Through application of several of these to the computation of models of the solar envelope we demonstrate that the sensitivity of the observed frequencies is in fact sufficient to distinguish even quite subtle features of the physics of solar matter. This opens up the possibility of using the Sun as a laboratory for statistical mechanics, under conditions that are out of reach in a terrestrial laboratory.     

Dynamic Structure of the GLONASS and GPS Orbital Space: Problem of Disposal of Retired Objects

The paper presents the results of a study of the dynamic structure of the orbital space of the navigation systems GLONASS and GPS. It is shown that the dynamic structure of the GLONASS region is determined by the action of one stable Lidov–Kozai secular resonance. The motion of almost all the retired objects of the GLONASS system is stable throughout the 100-year study period. In the GPS region, there is an orbital resonance and a large number of secular resonances. Their combined influence leads to a rapid increase in the eccentricity of the orbits of the retired objects of the system. Features of the dynamic structure of the orbital space are used to find the graveyard (parking) orbits of the retired objects of navigation systems.     

The accuracy of observations of the Galilean satellites of Jupiter taken at the Abastumani Astrophysical Observatory of the Academy of Sciences of Georgia

The sets of photographic observations of the Galilean satellites of Jupiter taken at the Abastumani Astrophysical Observatory of the Academy of Sciences of Georgia are analyzed here. Positional observations of the system of Jupiter were made in the period from 1985 to 1994 with the use of the double Zeiss astrograph in order to determine the exact coordinates of Jupiter and its satellites. The accurate positions of the satellites and Jupiter itself, as well as their stellar (equatorial) coordinates relative to the stars of the currently available catalogs and the relative ??satellite ?? satellite?? coordinates were obtained from the observations. From the comparison of the observation results with the modern theories of motion of satellites, the accuracy in determining the positions of the satellites and Jupiter was analyzed. The results of observations are presented in the Pulkovo database of observations of Solar System bodies that is accessible to users at http://www.puldb.ru.     

On the formation of pulsar radiation diagrmas

A model of pulsars is discussed in which formation of a polar diagram of the radiation is influenced by the motion of the source around a neutron star with a velocity close to that of light. For a power-law frequency-spectrum of the radiation and isotropy of the diagram in a system of coordinates rotating with the source, the width of the observed pulse is shown to be independent of frequency.The proposed explanation of the second period characteristics of type CP 1919 pulsars is based on the effect of relativistic motion of the radiation source. The positions are established (relative to the axis of rotation of the star) of the local sources of radiation in the optical and in the radio ranges for the pulsar NP 0532. It is shown how the polarization characteristics of the optical radiation of this pulsar may be connected with the effects of relativistic orbiting of the source of radiation about the star.     

Closed solution of the Hill differential equation for short arcs and a local mass anomaly in the central body

The Hill differential equation describes the relative motion of a satellite w.r.t. a circular reference orbit. The deviations in the orbit are caused by a residual acceleration, which is small compared to the effect of the central gravitational field. In this paper, the acceleration of a local mass anomaly in the central body is considered, which rotates w.r.t. the inertial frame with a constant angular velocity. The mass anomaly is modeled by a superposition of radial base functions. The potential and the gradient of each base function are represented in the orbit by the Keplerian elements, the rotation rate of the central body and the parameters of the base function, i.e. the position of its center, the shape and a scaling factor. The inhomogeneous solution of the Hill differential equation for short arcs is found by means of the Laplace transform. A few lower orders of the solution require an additional Laplace transform, to consider the so-called resonance cases. The final deviations are described in a closed and differentiable formula of the Keplerian elements and the parameters of the base function.