On the classical expansion of the perturbing function in individual orbital elements

Starting from the classical expansion of the perturbing function in the three‐body problem, the transformation to individual orbital elements is performed in principle up to any degree in small parameters. Some corrections to the results presented in the well‐known article by Yuasa on secular perturbations of asteroids are given. Consequences for the expansion of the indirect part of the perturbing function are discussed. This revised version was published online in July 2006 with corrections to the Cover Date.     

A Programme to derive from terrestrial observations the rotation of the HIPPARCOS system with reference to the inertial system

The connection of the HIPPARCOS system with a quasi-inertial system can be reached by transforming the HIPPARCOS proper motions to absolute proper motions. The Tautenburg Schmidt telescope provides such proper motions with respect to extragalactic objects with an accuracy of 0″.6/100a. The telescope as well as the measuring and reduction technique are described. The accuracy of the link of the HIPPARCOS system to extragalactic objects depends on the accuracy of the transformation matrix which represents the time-depending part of the rotation matrix to be applied to the whole HIPPARCOS catalogue. To obtain a reliable estimate for the error of transformation we used the error propagation law. An accuracy of 0″.12/100a for the transformation can be achieved with six Tautenburg fields.     

河北省沧州地区重力变化的初步分析

重力复测资料表明,沧州地区出现趋势性变化,最大变幅达92×10~(-8)m/S~2。本文的分析结果认为,这种变化部分与沧州地区地面沉降有关,部分与地壳深部的变异因素有关,不排除该地区发生中强地震的可能性。     

Membership of faint stars in the globular cluster M3

A proper motion study from Tautenburg Schmidt plates is presented for the globular cluster M3 and its vicinity. The plates were scanned with the Automated Photographic Measuring (APM) system in Cambridge (UK). A photographic B,V photometry and star counts on the deepest plates were carried out. With a limiting magnitude of about B = 21.4 proper motions with an accuracy from 2 to 3 mas/yr have been obtained for stars with B 19. The proper motions were determined using a stepwise regression method with 3rd order polynomials in the plate-to-plate solutions with about 2000 reference galaxies. The results which were corrected for systematic errors dependent on position and magnitude of the stars were used for the determination of membership probabilities. We also looked for possible internal motions of M3.     

Discovery of a companion at the brown dwarf limit to the solar‐type star Gliese 29

Gliese 29 is a 7 to 8 Gyr old, southern Population I turnoff star with a large proper motion of 1″/yr. Using recent direct imaging observations with the 0.8 m Infrared Imaging System (IRIS) of the Universitätssternwarte Bochum near Cerro Armazones in Chile, we demonstrate that the faint source 2MASS J00402651–5927168 at a projected angular separation ρ = 6.″35 is a common‐proper‐motion companion to Gl 29. Provided this source is not part of a further subsystem, the IRIS J ‐ and K_s‐band photometry either implies a spectral type of about L2, based on its absolute magnitude, or an approximate mass M_B ≃ 0.077 M_⊙, suggesting that it may even be a brown dwarf. Assuming a face‐on circular orbit this faint companion orbits Gl 29 in 1880 years. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

洛阳城区土壤重金属污染现状评价

通过用基准值与表层土壤重金属含量对洛阳市城区表层土壤污染程度进行评价。人类活动和工业化进程加快,来自多方面的环境污染不断加重,造成土壤环境质量不断下降。现代工业生产及古人类活动是造成洛阳城区内局部地段严重污染的主要原因,自然地质作用现象轻微。     

Synthetic Proper Elements for Outer Main Belt Asteroids

For the orbits with low to moderate inclination and eccentricity, in the asteroid main belt, the analytically computed proper elements are accurate to a level very close to the best result achievable by any analytical theory. This fundamental limitation results from the infinite web of resonances and because of the occurrence of chaotic motions. Still, there are some regions of the belt in which these proper elements are of degraded accuracy, thus preventing a reliable definition of asteroid families and detailed studies of the dynamical structure. We have used a different method to compute asteroid proper elements, following the approach introduced in the LONGSTOP project to describe the secular dynamics of the major outer planets. By applying purely numerical techniques, we produced so-called synthetic proper elements for a catalog of 10,256 asteroids with osculating semimajor axes between 2.5 and 4.0AU.The procedure consisted of simultaneous integration of asteroid and planetary orbits for 2Myr, with online filtering of the short-periodic perturbations. The output of the integration was spectrally resolved, and the principal harmonics (proper values) extracted from the time series. For each asteroid we have also tested the accuracy and stability in time of the proper elements, and estimated the maximum Lyapunov Characteristic Exponent to monitor the chaotic behaviors. This provided information on the reliability of the data for each orbit, in particular allowing to select 1,852 cases for an extended integration (10Myr) of the orbits showing instability. The results indicate that for more than half of the cases the proper elements have a time stability improved by more than a factor 3 with respect to the elements computed by the previous analytical theory. But of course there are also unstable cases for which the proper elements are less accurate and reliable, the extreme examples being 23 orbits exhibiting hyperbolic escape from the solar system. This form of escape from the asteroid belt could be responsible for a significant mass loss over the age of the solar system.     

Apparent proper motions of radio sources from geodetic VLBI data

According to the most recent geodetic VLBI data, some of the radio sources that define the fundamental celestial reference frame are astrometrically unstable. In contrast to the stellar proper motions described by a linear function, the apparent proper motions of quasars are more complex. Therefore, they are difficult to approximate by a particular model. Being disregarded, the positional instability of the defining quasars can lead to a bias in the estimates of other parameters from observations, for example, the nutation angle corrections.     

方斑东风螺养殖方式的初步研究

2003年5～11月,水温24．5～32℃,pH8．1～8．3,盐度21．2～32．0时,在湛江市东海岛分别利用室内水泥池、对虾高位池、自然海区砂滩以及水泥沉箱进行了方斑东风螺(Babylonia areolate Larnarck)人工养殖方式的研究。试验结果表明,方斑东风螺养殖的合适密度为：室内水泥池300～400个／m^2高位池和天然海区砂滩100～200个／m^2,水泥沉箱0．63m^3 200～250个／箱;方斑东风螺最佳饵料为蟹类,其次为虾类,然后是鱼类。经过3个月的人工养殖,生长最快的方斑东风螺由平均壳高0．7cm长至4．8cm。     

近33年沧州海域围填海空间格局变化分析

利用1985—2018年6个时间段的Landsat TM、ETM、OLI遥感影像,使用面向对象的遥感提取方法,通过选取空间利用结构、开发利用程度、景观指数及质心转移分析了沧州市围填海空间格局变化特征。结果表明：33年间研究区内围填海活动剧烈,1985—2018年,沧州近岸海域新增围填海面积137.05 km²,围填用海规模随时间变化不断扩大。1985—2003年,围填海空间利用结构和类型经历了从以围填养殖用海为主到各类型围填用海兼备的演化过程。研究区内围填海强度逐渐上升,2018年围填海开发强度指数达到274.55。港口用海逐渐成为沧州近海海域围填海的主要类型,围海养殖用海次之。1985—2018年,沧州市围填海景观的聚集度指数与蔓延度指数均较高,平均聚集度指数高达99.4004,围填海景观分布具有较强的规律性。沧州市围填海质心不断向东南方向移动,说明沧州市围填海开发的重点区域逐步迁移至沧州南部海域。在当前围填海现状下,应注重后续围填海开发活动的合理规划和集约利用。