摘要
中国科学院国家授时中心根据VLBI2010技术规范要求研制的3台13 m射电望远镜,建成了我国第一套测地型VLBI(very long baseline interferometry)网,并进行实验观测。天线(射电望远镜接收信号的部分称之为天线)的指向精度直接影响到VLBI系统的观测性能,因此天线指向修正是VLBI网设施中最基础的工作。研究了影响13 m射电望远镜指向精度的物理根源,根据观测要求得出天线指向精度要求,并建立相对应的修正模型,根据13 m射电望远镜的情况,最终认定13 m射电望远镜采用18参数的修正模型;研究了13 m射电望远镜实际测定的天线方向图及十字扫描法技术;分析、比较各种归算方法,采用傅里叶函数拟合方法确定其射电源精确位置;利用射电源高精度位置的优势,精确地测定13 m射电望远镜各方向的指向误差,最后,用最小二乘法拟合得到18参数修正模型的系数值,实现了模型修正精度优于天线主瓣十分之一的目标,并对观测结果进行了验证。最终修正后指向精度为46.64",优于天线主瓣十分之一(53.9")的要求,达到VLBI系统观测要求。
The first wide band domestic geodetic VLBI(very long baseline interferometry)networks,developed by the National Time Service Center(NTSC)of the Chinese Academy of Sciences,that is composed of three 13-meter radio telescopes and is now on commissioning phase.The pointing accuracy of the antenna is directly affecting the observation performance of the VLBI system,so,the antenna pointing correction is of one of the most basic works of the system.In this thesis,the error sources of the antenna pointing are studied.In order to meet the requirements of astronomical observations,a pointing correction model is established.The antenna pattern is measured by cross-scan method.And a 18-parameter correction model is established.By analyzing and comparing various reduce methods,we adopt the Fourier function fitting method to determine the precise position of radio sources,then,measured antenna errors for all directions.Finally,the coefficient values of the 18-parameter correction model are obtained by least squares fitting method.The final corrected accuracy is 46.64",which is better than the one-tenth(53.9")of the main lobe of the antenna,thus meets the requirements of astronomical observations.
作者
吴文雅
马浪明
姚当
刘佳
吴元伟
杨旭海
WU Wen-ya;MA Lang-ming;YAO Dang;LIU Jia;WU Yuan-wei;YANG Xu-hai(National Time Service Center,Chinese Academy of Sciences,Xi’an 710600,China;Key Laboratory of Precise Positioning and Timing Technology,Chinese Academic of Sciences,Xi’an 710600,China;School of Electronic,Electrical and Communication Engineering,University of Chinese Academy of Sciences,Beijing 100049,China;School of Astronomy and Space Science,University of Chinese Academy of Sciences,Beijing 101048,China)
出处
《时间频率学报》
CSCD
2020年第1期41-53,共13页
Journal of Time and Frequency
基金
国家自然科学基金面上资助项目(11173026)
中国科学院国家授时中心青年创新人才资助项目
载人航天预研资助项目(0602)。
关键词
VLBI网
射电望远镜
天线修正模型
最小二乘法
very long baseline interferometry(VLBI)network
radio telescope
pointing model
least square method
