中国等高仪星表的现状和未来

自七十年代后期起，中国的４架光电等高仪就开始注重于旨在改进基本星表系统的观测．这４架光电等高仪均实现了现代化改造：实现全自动化操作和采用光子计数记录，这使得仪器能通宵达旦地工作，效率倍增．近年来用中国光电等高仪的观测已经编算出几部等高仪星表，其两个坐标（α和δ）的精度都很好，极限三等可达１１ｍ以上．将来这４架光电等高仪和即将用ＣＣＤ装备的Ⅲ型光电等高仪将会对基本天体测量做出更大贡献．     

1949．0至1979．0 ILS地极坐标的均匀化

自１９８４年起在天文计算中都采用ＦＫ５基本星表和新天文常数,这些变动直接影响了用天顶仪等光学仪器观测订定的地极坐标。本文论述了基本星表和天文常数变动后,对国际纬度服务（ＩＬＳ）订定的地极坐标的影响。结果表明：１）星表系统差对地极坐标的影响在ｘ和ｙ方向最大,分别约－０．００６”和－０．００４”;２）章动序列变动的影响在ｘ、ｙ方向最大波动分别为０．０１２”和０．０１０”。     

On derivation of EIH (Einstein–Infeld–Hoffman) equations of motion from the linearized metric of general relativity theory

The half-century old idea of Infeld to use the variational principle of the general relativity field equations is reminded to show that the commonly employed EIH (Einstein–Infeld–Hoffman) equations of motion may be derived from the linearized (weak-field) metric alone. Based on it, the linearized metric might be sufficient for post-Newtonian celestial mechanics and astrometry enabling one to derive the post-Newtonian equations of motion and rotation of celestial bodies as well as the post-Newtonian equations of light propagation within the general relativity framework.     

Constraining the orbits of small solar system bodies using spectroscopic Doppler shift measurements – a preliminary study

In this short paper we examine whether the measurement of Doppler shifts in the solar light reflected off an asteroid surface may improve the accuracy of the determined orbit. Our results suggest it will be worthwhile to use high‐resolution spectrographs, of the exoplanet‐hunting type, to measure those Doppler shifts. Spectroscopic Doppler shifts might improve the accuracy of Earth‐impact predictions, help to recover “lost” near‐Earth objects, and may also significantly enhance the knowledge about dynamics of the Kuiper belt. Future high‐resolution spectrographs on the VLT and the E‐ELT may thus have an important role in studies of Solar‐System dynamics and kinematics. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

基于高斯过程的日长变化预报

由于日长(length-of-day,LOD)变化具有复杂的时变特性,传统线性模型如最小二乘外推模型、时间序列分析模型等的预报效果往往不甚理想,所以将一种新型的机器学习算法—高斯过程(Gaussian processes,GP)方法用于LOD变化预报,并将预报结果同利用反向传播神经网络(back propagation neural networks,BPNN)和广义回归神经网络(general regression neural networks,GRNN)的预报结果以及地球定向参数预报比较竞赛(Earth Orientation Parameters Prediction Comparison Campaign,EOP PCC)的预报结果进行对比.结果表明,GP用于LOD变化预报是高效可行的.     

The XPM Catalogue: absolute proper motions of 280 million stars

We combined data from the Two-Micron All Sky Survey (2MASS) and USNO-A2.0 catalogues in order to derive the absolute proper motions of about 280 million stars distributed all over the sky excluding a small region near the Galactic Centre, in the magnitude range  12 < B < 19 mag  . The proper motions were derived from the 2MASS Point Sources and USNO-A2.0 catalogue positions with a mean epoch difference of about 45 years for the Northern hemisphere and about 17 years for the Southern one. The zero-point of the absolute proper motion frame (the 'absolute calibration') was specified with the use of about 1.45 million galaxies from 2MASS. Most of the systematic zonal errors inherent in the USNO-A2.0 catalogue were eliminated before the calculation of proper motions. The mean formal error of absolute calibration is less than 1 mas yr⁻¹. The XPM Catalogue will be available via CDS in Strasbourg during 2010. The generated catalogue contains the International Celestial Reference System positions of stars for the J2000 epoch, original absolute proper motions, as well as   B , R , J , H   and K magnitudes. A comparison of the proper motions obtained in this work with the data of other recent catalogues of quasars was fulfilled.