低纬子午环应有的观测精度

本文介绍了在拟定总体设计方案时针对实际需要与可能提出的基本要求 ;对各种误差的测定方法与传统子午环作了比较 ,并且列出了低纬子午环新增加的仪器误差 ;文章根据在仪器较稳定条件下各种误差的测定精度 ,对该仪器的应有观测精度作了估计 ,指出每颗天体位置的单次测定精度不应低于± 0 .1 0″,最后还分析了目前尚未达到应有精度的原因。     

低纬子午环仪器误差的测定及其处理方法

仪器误差的精确测定和消除对于提高子午环的观测精度有着至关重要的意义。本文简单介绍了 低纬子午环的观测原理和仪器结构，系统地探讨了它的各种仪器误差的来源、测定和和。     

等高仪光子计数观测资料的处理

在光子计数资料的处理方法设计不完善时，有可能会大大影响光电等高仪的观测结果。本文提出了一套从平滑，搜索到定中心的光子计数资料处理方法，通过与原方法进行了９天（含满月夜）的同步处理比较，新的处理方法得到的星数是原方法结果的１．４８倍，单星测定精度提高０″０２，并且基本克服了天光的影响。     

我国局部网对近地测地卫星定轨精度的估计

本文利用模拟观测资料，估计了中国卫星跟踪网对近地测地卫星定轨和测定一些跟踪站地心坐标所能达到的精度。同时分析了近地卫星定轨的主要误差源，如大气模型、地球引力场模型的不确定性和跟踪网站坐标的误差等所产生的影响。     

天文选址数字云量白天观测处理方法

云量观测是天文选址的重要考察项目.本文报告一种数字云量观测的处理方法,可以快速准确地计算选址点的云量值,避免了目视云量观测的人为误差.云量处理实验结果表明,该方法是合理可靠的, 在天文选址后期工作中能有效使用.该方法应用于西藏物玛观测点的云量观测统计,给出与同期目视云量的相关比较,并讨论数字云量处理的精度和改进方案.     

低纬子午环仪器误差的测定及其处理方法

仪器误差的精确测定和消除对于提高子午环的观测精度有着至关重要的意义。本文简单介绍了低纬子午环的观测原理和仪器结构，系统地探讨了它的各种仪器误差的来源、测定和处理方法。为了进一步完善采用组合固定角距法测定对径改正的方法，在第三章，研究了提高对径改正测量精度的方法，重新推导了对径改正的计算公式，并就某些具体的条件，对其进行了模拟验证，得到了较为满意的结果     

二维太阳光谱观测方法和技术

经典的太阳光谱观测是一维的，它有很大的局限性。从５０年代起，天文工作者采用多种方法开展二维太阳光谱观测，已经研制出一系列仪器，建立完整的资料归算程序，取得优良成果。在二维观测资料的基础上，用理论方法推出深度分布，可以得出三维的立体图像，这会成为太阳研究的主要方法之一。     

用α—修正平均平滑月掩星观测资料

因为短的积分时间（0^s.001）和月球附近很强的背景光这度，月掩星观测资料通常需要进行某种处理以除去噪声，而α-彩好的消除噪声能力，可以用来平滑月掩星观测资料，很少甚至完全不影响掩星的衍射图象。本文介绍了α-修正平均方法并指出对α=0，ι=9的α-修下平均是对月掩星观测资料的最佳滤波器。     

野值预剔除方法的改进

在初轨有较大误差时，传统的光学资料野值预剔除方法——截断最小二乘L估计法不能有效地剔除野值．从门限和模型两方面改进野值预处理方法，即改用统计中误差定门限．将残差的线性模型改为2次曲线模型，结果为：对于模拟产生的所有卫星弧段，在初轨有10^-4（半长轴α为其5％，以下不再说明）误差情况下，野值比例都能降低到10％以下．     

太阳射电观测中蝴蝶斑的一种消除方法

本试图根据蝴蝶斑的分布特征，采用平滑滤波的方法，消除太阳射电高时间分辨率观测资料中，由于某种干扰引起的蝴蝶斑，从而达到在这种资料中提取有用太阳信息的目的。     

利用3次方位观测天基初轨确定新方法

提出了一种适用于天基空间目标光学观测的初始轨道确定新方法. 通过对比地基和天基观测的几何构型, 分析了利用天基光学观测数据进行初轨确定时计算收敛到观测平台自身轨道的原因. 基于轨道半通径方程和改进Gauss方程, 推导出了斜距条件方程组的解析形式, 将天基光学观测的初轨确定问题转换为求解关于观测时刻斜距变量的非线性条件方程组的问题. 利用轨道能量约束减小了解的搜索区域, 消除了方程组的奇点. 最后利用天基实测数据验证并分析了非线性条件方程组根的性质, 利用低轨光学观测平台对低、中、高轨和大椭圆轨道空间目标的仿真观测数据验证了方法的有效性.     

星载GPS相位观测值非差运动学定轨探讨

在几何法、动力学法和减缩动力学法定轨基础上，探讨了星载GPS相位观测值非差运动学定轨方法及其实现程序。该方法无需复杂的力学模型和地面资料，只需LEO(Low Earth Orbit)卫星上的GPS数据和IGS的GPS精密星历产品，它计算简单、方便，能快速、高精度地确定轨道，同时，还能确定一些动力学参数，但没有轨道预报功能；针对法方程系数矩阵比较庞大，提出了矩阵分块、上三角化的参数解算方法，并用CHAMP卫星资料分析了上述方法的定轨精度。     

Spacecraft Orbit Determination with The B-spline Approximation Method

It is known that the dynamical orbit determination is the most common way to get the precise orbits of spacecraft. However, it is hard to build up the precise dynamical model of spacecraft sometimes. In order to solve this problem, the technique of the orbit determination with the B-spline approximation method based on the theory of function approximation is presented in this article. In order to verify the effectiveness of this method, simulative orbit determinations in the cases of LEO (Low Earth Orbit), MEO (Medium Earth Orbit), and HEO (Highly Eccentric Orbit) satellites are performed, and it is shown that this method has a reliable accuracy and stable solution. The approach can be performed in both the conventional celestial coordinate system and the conventional terrestrial coordinate system. The spacecraft's position and velocity can be calculated directly with the B-spline approximation method, it needs not to integrate the dynamical equations, nor to calculate the state transfer matrix, thus the burden of calculations in the orbit determination is reduced substantially relative to the dynamical orbit determination method. The technique not only has a certain theoretical significance, but also can serve as a conventional algorithm in the spacecraft orbit determination.     

加速仪数据在CHAMP卫星精密定轨中的贡献

通过用几个实例计算，评估了CHAMP卫星加速仪数据对SLR数据定轨精度的贡献．结果显示用加速仪数据代替非保守力对CHAMP卫星进行精密定轨时，其SLR的残差从原来的16．5cm减少到2．7cm，与精密轨道相比，卫星位置误差由18．9cm减少到6．2cm(一天资料)．     

Kinematic Precise Orbit Determination for LEO Satellites Using Space-borne Dual-frequency GPS Measurements

As a special approach to orbit determination for satellites with spaceborne GPS receivers, the kinematic Precise Orbit Determination (POD) is independent of any mechanical model (e.g., the Earth gravity ?eld, atmospheric drag, solar radiation pressure, etc.), and thus especially suitable for the orbit determination of Low Earth Orbiting (LEO)satellites perturbed strongly bythe atmosphere. In this paper, based on the space-borne dual-frequency GPS data, we study the kinematic POD, discuss the pre-processing of the data, and construct an algorithm of zero-difference kinematic POD. Using the observational data from GRACE (Gravity Recovery And Climate Experiment) satellites covering the whole month of February 2008, we verify the effectiveness and reliability of this algorithm. The results show that the kinematic POD may attain an accuracy of about 5 cm (with respect to satellite laser ranging data), which is at the same level as the dynamic and reduced-dynamic PODs     

Review of Hinode results

Hinode is an observatory‐style satellite, carrying three advanced instruments being designed and built to work together to explore the physical coupling between the photosphere and the upper layers for understanding the mechanism of dynam‐ ics and heating. The three instruments aboard are the Solar Optical Telescope (SOT), which can provide high‐precision photometric and polarimetric data of the lower atmosphere in the visible light (388–668 nm) with a spatial resolution of 0.2–0.3 arcseconds, the X‐Ray Telescope (XRT) which takes a wide field of full sun coverage X‐ray images being capable of diagnosing the physical condition of coronal plasmas, and the EUV Imaging Spectrometer (EIS) which observes the upper transition region and coronal emission lines in the wavelength ranges of 17–21 nm and 25–29 nm. Since first‐light observations in the end of October 2006, Hinode has been continuously providing unprecedented high‐quality solar data. We will present some new findings of the sun with Hinode, focusing on those from SOT (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Instruments of RT-2 experiment onboard CORONAS-PHOTON and their test and evaluation I: ground calibration of RT-2/S and RT-2/G

Phoswich detectors (RT-2/S & RT-2/G) are major scientific payloads of the RT-2 Experiment onboard the CORONAS-PHOTON mission, which was launched into a polar Low Earth Orbit of around 550 km on 2009 January 30. These RT-2 instruments are designed and developed to observe solar flares in hard X-rays and to understand the energy transport processes associated with these flares. Apart from this, these instruments are capable of observing Gamma Ray Bursts (GRBs) and Cosmic diffuse X-ray background (CDXRB). Both detectors consist of identical NaI(Tl) and CsI(Na) scintillation crystals in a Phoswich combination, having the same diameter (116 mm) but different thicknesses. The normal working energy range is from 15 keV to 150 keV, but may be extendable up to ~1 MeV. In this paper, we present the RT-2/S and RT-2/G instruments and discuss their testing and calibration results. We used different radio-active sources to calibrate both detectors. The radio-active source ⁵⁷Co (122 keV) is used for onboard calibration of both instruments. During its lifetime (??3?C5 years), RT-2 is expected to cover the peak of the 24th solar cycle.     

Interactions of large meteoroids and small interplanetary bodies with the Earth's atmosphere: Theories and observational constraints

Problems of hypervelocity interaction of large bodies with the Earth's atmosphere has attracted more attention during last few years. Several new concepts of dynamical explosive fragmentation of strong interplanetary bodies at extremely low heights under dynamic pressures of hundreds of Mdyn/cm² were published. Comparison of these theoretical models with precise observations has not yet been done, because data on atmospheric penetration of large bodies are not available.Single body theory with sudden gross-fragmentation was successfully applied to photographic observations of fireballs. The largest bodies observed have sizes up to several meters. The highest dynamic pressure acting on these observed bodies reached slightly over 100 Mdyn/cm². All these photographed fireballs follow theoretical concepts of motion of either the single-body or the single-body with gross-fragmentation under dynamic pressures in the range from 1 to 12 Mdyn/cm². When this theory has been applied to photographic observations, typical standard deviation of the distance flown in the trajectory has been found in a range of 10 to 30 m for one observed distance corresponding also to the geometrical precision of the observations. This model can explain all good observations of atmospheric trajectories of meteoroids up to initial sizes of several meters with high precision. Also the three photographed and one videorecorded meteorite falls fit to this concept completely.The most important phenomenon of atmospheric motion of meteoroids up to several meters in size is the ablation with final stage of hot vapor from ablated material. Spectral records of meteoroids up to several meters in size, down to a height of 16 km and for various velocities show overwhelming radiation of rather low excited metalic atoms (several eV; temperatures 3000 to 5000 K) in the pass-band of visible light. Radiation from high excited atoms of either atmospheric or ablational origin forms only an insignificant part of visible radiation.Contrary to this regime, theories of very large bodies contain ablation mostly in the form of explosive fragmentation. Ablation at higher heights is negligible. This absence of classical ablation and fragmentation at low dynamic pressures for large bodies (contrary to observations of smaller bodies) brings the body to lower heights without too much change of size and makes thus the dynamic pressure much higher than in reality. In any case the change of body dynamics and radiation going from sizes of several meters (observed regime) to sizes of several tens of meters (hypothetical regime) may be crucial for our understanding of dynamics and radiation of large body penetration through the low atmosphere to the Earth's surface. Observations of atmospheric trajectory of these bodies with sufficiently high precision are extremely needed.     

The Data Depth-weight-kernel Estimation of the Model Error of Satellite Orbit Determination

It is an objective fact that there exists error in the satellite dynamic model and it will be transferred to satellite orbit determination algorithm, forming a part of the connotative model error. Mixed with the systematic error and random error of the measurements, they form the unitive model error and badly restrict the precision of the orbit determination. We deduce in detail the equations of orbit improvement for a system with dynamic model error, construct the parametric model for the explicit part of the model and nonparametric model for the error that can not be explicitly described. We also construct the partially linear orbit determination model, estimate and fit the model error using a two-stage estimation and a kernel function estimation, and finally make the corresponding compensation in the orbit determination. Beginning from the data depth theory, a data depth weight kernel estimator for model error is proposed for the sake of promoting the steadiness of model error estimation. Simulation experiments of SBSS are performed. The results show clearly that the model error is one of the most important effects that will influence the precision of the orbit determination. The kernel function method can effectively estimate the model error, with the window width as a major restrict parameter. A data depth-weight-kernel estimation, however, can improve largely the robustness of the kernel function and therefore improve the precision of orbit determination.     

Bayesian joint analysis of cluster weak lensing and Sunyaev–Zel'dovich effect data

As the quality of the available galaxy cluster data improves, the models fitted to these data might be expected to become increasingly complex. Here we present the Bayesian approach to the problem of cluster data modelling: starting from simple, physically motivated parametrized functions to describe the cluster's gas density, gravitational potential and temperature, we explore the high-dimensional parameter spaces with a Markov-Chain Monte Carlo sampler, and compute the Bayesian evidence in order to make probabilistic statements about the models tested. In this way sufficiently good data will enable the models to be distinguished, enhancing our astrophysical understanding; in any case the models may be marginalized over in the correct way when estimating global, perhaps cosmological, parameters. In this work we apply this methodology to two sets of simulated interferometric Sunyaev–Zel'dovich effect and gravitational weak lensing data, corresponding to current and next-generation telescopes. We calculate the expected precision on the measurement of the cluster gas fraction from such experiments, and investigate the effect of the primordial cosmic microwave background (CMB) fluctuations on their accuracy. We find that data from instruments such as the Arcminute Microkelvin Imager (AMI), when combined with wide-field ground-based weak lensing data, should allow both cluster model selection and estimation of gas fractions to a precision of better than 30 per cent for a given cluster.