FAST望远镜40米模型天文观测软件的开发

针对FAST的天文观测要求,对其天文观测软件进行了设计与开发。首先介绍了FAST天文观测的原理,对天文观测软件进行了需求分析。而后提出了馈源天文运动轨迹规划算法,并进行了仿真。针对其轨迹要求给出了控制方法,对天文观测控制软件进行了设计与实现。最后通过现场实地实验,验证了本文所提的算法与软件的可行性。     

Similarity model of feed support system for FAST

A new design of feed support system for Five hundred meter Aperture Spherical Telescope (FAST) is proposed in this paper. According to the similarity theory, a 1:15 scale model of feed support system has been built to make systemic research on the feasibility of the system. Then the control system and hardware structure of the feed support system are illustrated. A complete astronomical observation track is run by the scale model and the experiments results demonstrate that the new feed support system can satisfy the observation accuracy requirement of FAST.     

FMG载荷地面试观测导行跟踪系统的设计与实现

全日面矢量磁像仪(Full-disk vector MagnetoGraph, FMG)是先进天基太阳天文台(Advanced Space-based Solar Observatory, ASO-S)卫星的3台主载荷之一,为开展FMG全系统性能测试和定标试验,已搭建用于FMG外场测试的地面试观测平台.利用该平台模拟FMG在轨跟踪状态,研制了基于全日面太阳图像的望远镜导行系统.该系统通过大面阵CCD (Charge Coupled Device)采集太阳像、多重逻辑条件判定、微调恒动跟踪速度校正偏移等策略,实现了RMS (Root Mean Square)优于1′′/30 min的跟踪精度.通过分析FMG方案阶段试观测的太阳纵向磁图,开启导行30 min后磁图特征点在赤经方向的偏移比恒动条件下减少17.5′′,提升了磁图空间分辨率.测试过程中该系统达到设计指标且工作稳定,为FMG地面试观测提供了良好的技术支撑.     

FAST望远镜两轴转向机构结构方案优化

FAST馈源支撑系统承载和驱动馈源运动,进行对天体的高精度跟踪观测.在实时的定位调整中,两轴转向机构起着辅助调整接收机姿态角的作用.为满足FAST两轴转向机构的重量及刚度要求,选择了一种空间刚架式的结构构型.提出了反映结构柔顺度及重量约束的目标函数,以各类杆件的截面面积以及整个结构的高度、半径等几何参数作为优化变量,采...     

Study of central control system for FAST

FAST(The Five-Hundred-Meter Aperture Spherical Radio Telescope) is an under-building radio telescope which will be the largest single dish in the world. Through the study of the central control system, in accordance with the actual operation of the telescope and observation process, this article introduces the physical models for engineers and observers, the central control system architecture design, basic support modules and the necessary interfaces. We simulated observation control process and telescopes monitoring and control process, and took Active Reflector System as a subsystem example to complete the control system design and implementation using EPICS (Experimental Physics and Industrial Control System). The Central control system, with active reflector systems, feed supporting system has been taken to an integration test at Miyun model. In the case of the normal operation of the various sub-systems of the Miyun model by the central control system, a coordinated control is achieved.     

Short-period and long-period perturbations of a spherical satellite due to direct solar radiation

On the basis of expressions derived by Kozai, and new ones developed here, a detailed, semianalytic algorithm is presented for calculating radiation-pressure perturbations in the Keplerian elements. Through some simple modifications, the algorithm is also made to hold whene=0 and/ori=0. The perturbations are obtained by summing over the sunlit segment of the satellite's orbit during each revolution or part thereof. The end points of this segment are evaluated numerically once per revolution. The effect of the inherent uncertainties in the boundaries of the Earth's shadow is discussed. The algorithm is tested by means of numerical integration of the equations of motion and through comparisons with observations of the balloon satellite 1963 30D during a 200-day interval.     

1．3厘米接收机背架调整系统设计

基于新疆天文台研制的1．3em双极化制冷接收机的安装及观测需求,设计了其背架调整系统。首先,通过力学分析选择合适的滚珠丝杠及驱动电机;其次,通过对电机进行测试,研制电机驱动模块,以满足安装要求;最后,编写电机驱动控制软件,实现终端对接收机馈源的精确控制。     

实时相关跟踪图像处理系统

文章介绍了怀柔太阳观测基地最近完成的一套实时高分辨太阳磁场观测系统。系统采用局部相关跟踪算法来提高磁场观测数据的空间分辨率，同时对相关跟踪算法的实现程序进行了优化以满足常规太阳磁场观测的要求。通过对试观测和常规观测数据的分析，我们发现：1）该系统能够大大提高单色像、磁场数据的对比度和空间分辨率；2）对相关跟踪算法的优化大大提高了系统的时间分辨率，系统可以投入常规观测使用。     

Innovative methods of correlation and orbit determination for space debris

We propose two algorithms to provide a full preliminary orbit of an Earth-orbiting object with a number of observations lower than the classical methods, such as those by Laplace and Gauss. The first one is the Virtual debris algorithm, based upon the admissible region, that is the set of the unknown quantities corresponding to possible orbits for a given observation for objects in Earth orbit (as opposed to both interplanetary orbits and ballistic ones). A similar method has already been successfully used in recent years for the asteroidal case. The second algorithm uses the integrals of the geocentric 2-body motion, which must have the same values at the times of the different observations for a common orbit to exist. We also discuss how to account for the perturbations of the 2-body motion, e.g., the J ₂ effect.     

关于太阳系小天体轨道演化的算法研究

太阳系小天体的运动对应—哈密顿(Hamilton)系统,对其轨道演化的数值研究宜采用哈密顿算法(即辛算法)。本文将仔细讨论这一问题,并以主带小行星的运动为例,较系统地介绍几种辛算法对应的显式辛差分格式。     

Modeling of A Feed Support System for Fast

As an engineering demonstrator for SKA, the Five-hundred-meter Aperture Spherical Telescope (FAST) is proposed in China. This paper is focused on one of the most critical components of FAST, the feed support system. The engineering concept, the configuration and results from model experiments are presented. The mechanical characteristics of the structure are analyzed. The performance of the feedback control system of the model is described. The feasibility of the design is tentatively confirmed by the experiments described at the end of the report.     

Design and optimization of cross bow-tie dipole feed with cavity for FAST

A cross bow-tie dipole feed with cavity and symmetrical E and H plane pattern is presented for the Five hundred-meter Aperture Spherical radio Telescope(FAST).In this paper we describe the design,optimization and simulation results of a wide-band cross dipole feed with cavity covering the frequency range from 300 MHz to 600 MHz for FAST.The main goals of our design are to ensure that,(1)we cover the octave bandwidth,(2)the feed has symmetrical E and H plane pattern,and(3)the physical dimension is suitable for mounting it in the reserved position of the FAST feed cabin.The initial results indicate that we have met most of our design goals.This kind of feed had been equipped with the multi-beam receiver to carry out observation on the platform of FAST cabin.     

A novel algorithm for generating libration point orbits about the collinear points

This paper presents a numerical algorithm that can generate long-term libration points orbits (LPOs) and the transfer orbits from the parking orbits to the LPOs in the circular-restricted three-body problem (CR3BP) and the full solar system model without initial guesses. The families of the quasi-periodic LPOs in the CR3BP can also be constructed with this algorithm. By using the dynamical behavior of LPO, the transfer orbit from the parking orbit to the LPO is generated using a bisection method. At the same time, a short segment of the target LPO connected with the transfer orbit is obtained, then the short segment of LPO is extended by correcting the state towards its adjacent point on the stable manifold of the target LPO with differential evolution algorithm. By implementing the correction strategy repeatedly, the LPOs can be extended to any length as needed. Moreover, combining with the continuation procedure, this algorithm can be used to generate the families of the quasi-periodic LPOs in the CR3BP.     

Instrumental Response Function for Filtergraph Instruments

Dopplergrams and magnetograms arising from filtergraph instruments such as the Michelson Doppler Imager (MDI), the Helioseismic and Magnetic Imager (HMI), or the Hinode Narrow Band Filter Imager are generally associated with observation heights that are derived from the contribution function of the targeted absorption line, irrespective of the instrument characteristics. Observation heights are important for interpreting the phases of propagating waves, and for the diagnostics of the solar atmosphere. I show in this paper that the formalism presented by Ruiz Cobo and del Toro Iniesta (Astron. Astrophys. 283, 129, 1994) provides a straightforward approach to associate an observation height for each observable given the instrumental algorithm, the transmission profiles and the local stratification at the point of observation. To demonstrate the method, I construct a simple radially symmetric sunspot model and calculate the mean observation height for various MDI observables as a function of horizontal location. It is shown that different ways of measuring the same quantity can result in different observation heights, that the offset velocity caused by the spacecraft motion has to be taken into account, and that observation heights in sunspots vary beyond the pure geometric effect of the Wilson depression.     

Phasing of segmented mirrors: a new algorithm for piston detection

The point spread function of a segmented-mirror telescope is severely affected by segment misalignment, which can nullify the performance of adaptive optics systems. The piston and tilt of each segment must be precisely adjusted in relation to the other segments. Furthermore, the direct detection of the alignment error with natural stars would be desirable in order to monitor the errors during astronomical observation.
We have studied the lost information of the piston error caused by the presence of atmospheric turbulence in the measurements of curvature, and present a new algorithm for obtaining the local piston using the curvature sensor. A phase-wrapping effect is shown as responsible for the loss of curvature information and so the piston errors can no longer adequately be mapped; this happens not only in the presence of atmospheric turbulence, but also in its absence.
Good results are obtained using a new iterative method for obtaining the local piston error map. In the presence of atmospheric perturbation, the turbulent phase information obtained from a Shack–Hartmann sensor is introduced in our new iterative method. We propose a hybrid sensor composed of a curvature sensor and a Shack–Hartmann sensor, in order to complete all the information for the phasing. This design takes a short computation time and could be used in real time inside an adaptive optics system, where tilt and piston errors must be corrected.     

关于近地小行星轨道演化的初步探索

本文采用改进的显式辛算法和嵌套的PKF7（8）积分器同时对86颗已命名（或编号）的近地小行星的轨道演化进行了数值研究，在103－104年的时间尺度上，给出了这些小行星轨道演化的状况以及它们与几颗大行星靠近的最小距离，特别是与地球接近的最小距离可小于0．01天文单位，甚至可能比月球还更靠近地球．     

Interval Algorithm for the Planetary Problem

To calculate the dynamics of celestial bodies, we suggest the nonclassic interval algorithm based on taking into account explicitly the limitations of the resolving capacity of instrumental observation facilities. This algorithm is consistent with the correspondence principle (has a classic limit) and is a system of integer mappings of a recurrent type which is free of the effect of the round-off error accumulation. Another feature is its relative simplicity, which allowed us to make the calculations less time-consuming as compared to the classic approach. This algorithm was used to calculate the evolution of the Solar System's planetary orbits over times of about 500 million years. The calculations support the results obtained earlier by classic methods and make it possible to conclude that the suggested interval approach can be adequately applied to the planetary problem under consideration.     

A remark on the apsidal motion in slose binary systems

Dynamics of the apsidal motion in close binary systems are discussed. A comparison between the solution for the perfect fluid system and the solution for the rigid system reveals that some overall viscosity in the interior of distorted star has a right tendency to reconcile the observation of apsidal motion with the theory of internal structure.     

A global regularisation for integrating the Caledonian symmetric four-body problem

Several papers in the last decade have studied the Caledonian symmetric four-body problem (CSFBP), a restricted four-body system with a symmetrically reduced phase space. During these studies, difficulties have arisen when the system approaches a close encounter. These are due to collision singularities causing numerical integration algorithms to fail. In this paper, we give the full details of a regularisation approach that now enables us to study these close encounters and collision events. The resulting equations of motion can be efficiently integrated by a high-order integrator. The results from numerical testing of the algorithm verify that the regularisation is advantageous in preserving numerical stability. The effectiveness of the approach is illustrated for a range of CSFBP orbits. Numerical experiments show that the newly developed regularisation algorithm has excellent energy conservation properties.