低频射电望远镜阵列宽视场成像技术研究

发布时间：2018-01-22 13:49

  本文关键词： 仪器 干涉仪 方法 观测 技术 干涉测量 技术 图像处理 射电连续谱 普通　出处：《天文学报》2017年05期 　论文类型：期刊论文

【摘要】：低频射电望远镜阵列宽视场成像正面临着一系列难点问题,其中最关键的问题是非共面基线效应.它的存在使得忽略w项将导致最终图像出现畸变,且随着视场的增大而加重.综述并剖析了几种w项改正算法及其技术原理,并分析了它们的计算成本和计算复杂度,进而分析比较了它们的优缺点.以平方公里阵(Square Kilometre Array,SKA)射电望远镜第1阶段低频阵列为研究对象,选取faceting和w-projection成像算法进行了仿真实验.与传统的二维傅立叶变换成像算法进行对比,分析了它们的成像质量和正确性,结果表明这两种算法在宽视场成像方面均明显优于二维傅立叶变换方法.还具体分析了分面(facet)的数目对faceting成像质量和运行时间的影响,以及w步数对w-projection成像质量和运行时间的影响,表明facet数目和w步数的选择必须合理.最后,分析了数据量大小对这两种成像算法运行时间的影响,表明这两种算法在进行海量数据处理前,需要作算法优化改进.研究结果为后续进一步综合分析宽视场成像技术以及这些技术的实用性研究提供了有价值的参考.
[Abstract]:Low-frequency radio telescope array wide-field imaging is facing a series of difficult problems, among which the key problem is the non-coplanar baseline effect, which makes ignoring the w term will lead to distortion of the final image. And with the increase of the field of view, this paper summarizes and analyzes several w term correction algorithms and their technical principles, and analyzes their computational cost and complexity. Their advantages and disadvantages are analyzed and compared. The phase 1 low frequency array of the square square Kilometre Arrayska radio telescope is taken as the research object. Faceting and w-projection imaging algorithms are selected to carry out simulation experiments, and compared with the traditional two-dimensional Fourier transform imaging algorithm, their imaging quality and correctness are analyzed. The results show that the two algorithms are superior to the two-dimensional Fourier transform method in wide-field imaging, and the facet is analyzed in detail. The effect of the number of faceting on the imaging quality and operation time. The influence of w step number on the quality and running time of w-projection shows that the selection of facet number and w step number must be reasonable. Finally. The effect of the size of data on the running time of the two imaging algorithms is analyzed, which indicates that the two algorithms are before the massive data processing. The results provide a valuable reference for the further comprehensive analysis of wide-field imaging techniques and their practicability.
【作者单位】： 中国科学院上海天文台;中国科学院射电天文重点实验室;
【基金】：政府间科技合作项目(2016YFE0100300) 中国科学院天文财政专项;中国科学院青年创新促进会资助
【分类号】：P111.44
【正文快照】： 1引言为了探索宇宙再电离和引力波等宇宙学中最具吸引力和发展前途的前沿领域,国际上先后投入巨资建设了许多大型低频(小于400 MHz)射电望远镜阵列,包括荷兰的低频阵列(Low Frequency Array,LOFAR)[1];美国-澳大利亚联合建成的默奇森广角阵列(Murchison Widefield Array,MWA)[，

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