YNAO OpenIR  > 应用天文研究组
地平式天文望远镜高精度指向模型的研究与建立
郑向明
Subtype博士
Thesis Advisor熊耀恒
2010-01-05
Degree Grantor中国科学院研究生院(云南天文台)
Place of Conferral北京
Degree Discipline天体测量与天体力学
Keyword望远镜 指向模型 指向精度 图像处理 数据分析
Abstract天文望远镜重要的技术指标之一就是指向精度。 本论文介绍了通过建立模型提高望远镜指向精度常用的两种方法:基本参数模型和球谐函数模型。 在1.2m地平式望远镜技术升级后,为了满足激光测卫和自适应光学的工作需要,作者首先建立了初模型,保证恒星能进入到探测器CCD的视场里。针对1.2m望远镜的结构特性,再采用球谐函数模型方法,选取了一个取到四阶的带谐项和相应各阶均只是一次田谐项的球谐函数作为全天指向修正模型,使之具有更大的普适性。同时针对编码器细分误差这个具体因素建立相应的编码器小周期模型。经过以上几种模型修正后的指向精度达到了几个角秒的量级,圆满地满足了近几年观测任务的要求。 由于环境温度、湿度、风速及风向的变化等多方面的偶然因素,以及在作全天指向修正模型选取恒星时不能完全均匀分布全天区,导致拟合时在某些局部天区指向精度不同。同时鉴于对月球激光测距试验、高轨卫星定轨、恒星测光度差等工作需要,本文独特地提出并实现了用观测目标轨道周围的一定数量的恒星作局部指向修正模型改正。使之沿观测目标轨道上望远镜的指向达到角秒量级的高精度。这项研究工作至今未见报道。 特别介绍了在建立模型过程中需要注意和解决的几个问题,如:CCD视场中心与光轴中心的偏差、编码器零点误差、视场旋转、CCD视场大小和象元当量、CCD观测星象定心算法产生的偏差、跟踪过程带来的误差。 通过本文的研究工作,作者系统地掌握了地平式望远镜指向模型建立的理论,再从大量的实践工作中,作者建立了针对望远镜结构特性、观测对象特殊要求等等的各种指向修正模型,既使1.2m望远镜达到了角秒量级的高指向精度,又为高性能指标地平式望远镜的实现提供了广泛而实用的借鉴。
Other AbstractPointing accuracy is an important technical indicator of an astronomical telescope. This paper describes two ways to improve the pointing accuracy by using models: the basic parameter model and the spherical harmonic function model. After the technological update of the 1.2m telescope, in order to meet the operational needs of laser and adaptive optics, the author established an initial model to ensure that a star can enter the field view of the CCD detector. Subsequently, considering the structural characteristics of the 1.2m telescope, the author selected as the global pointing model a spherical harmonic function up to the fourth harmonic order and with the corresponding terms of each harmonic order being the first order tesseral harmonic terms. At the same time for the segmentation errors of the encoder measuring angles, a small-period model was used. After the corrections with the above several models, the pointing accuracy reaches within a few arcsecs, satisfying the requirements for observational tasks in recent years. Because of random factors, such as changes in temperature,humidity, wind speed or wind direction of the environment, also because of the non-uniform distribution of stars selected for setting the global pointing model, the result pointing accuracy from fitting being differ in some localized sky regions. In addition, to meet the needs of the lunar laser ranging experiment, measurement of orbits of high-altitude satellites, and differential photometry of stars, this paper proposes a unique and realized scheme to use a number of stars around a target as local calibrators of directions in the pointing model. With such a scheme the pointing accuracy of the telescope along the target orbit can be achieved with a precision as high as a few arcsecs. This study has not yet been reported. The factors that need to be considered in the modeling are especially presented. These include offset of the center of field view of CCD from optical axis, zero-point error of the encoder, the field rotation, size of field view of CCD and pixel equivalent, error of the algorithm to locate the center of image, error caused by tracking, etc. Through this study, the author has achieved a comprehensive understanding of the theory of pointing model for alt-az telescope. Based on many practices, the author further established various pointing models to accommodate to the structural characteristics of the telescope and special observational requirements. These make the 1.2m telescopes to reach a high pointing accuracy on the level of a few arcsecs, and in the mean time provide general references for achieving high performance of alt-az telescope.
Subject Area天文学
Pages78
Language中文
Document Type学位论文
Identifierhttp://ir.ynao.ac.cn/handle/114a53/7352
Collection应用天文研究组
Recommended Citation
GB/T 7714
郑向明. 地平式天文望远镜高精度指向模型的研究与建立[D]. 北京. 中国科学院研究生院(云南天文台),2010.
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