论文标题
快速算法以近似无线电干涉宽场成像中位置依赖性点扩散函数响应
Fast algorithms to approximate the position-dependent point spread function responses in radio interferometric wide-field imaging
论文作者
论文摘要
渴望宽阔的视野,较大的分数带宽,高灵敏度,高光谱和时间分辨率使无线电干涉指标驱动了大数据革命点,在这些革命中,数据在至少三个维度中表示,具有光谱窗口,底线,源,源等轴的三个维度;每个轴都有自己的子维度集。与存储和处理这些数据相关的成本非常大,因此已经研究了几种压缩干涉数据和/或加速处理的技术。不幸的是,基于平均的可见性数据压缩方法对数据保真度有害,因为点扩散函数(PSF)取决于位置依赖性,即扭曲和减弱是距相中距离距离的函数。 PSF的位置依赖性变得更加严重,需要更多的PSF计算以进行广阔的成像。反卷积算法必须在主要和次要周期中考虑变形,以正确减去PSF并恢复图像的保真度。这种方法在计算中很昂贵,因为在每个反卷积迭代中必须计算扭曲的PSF。我们提出了两种算法,以更少的计算近似这些位置依赖性PSF。第一种算法近似于$ UV $平面中的位置依赖性PSF,第二算法近似于图像平面中的位置依赖性PSF。使用Meerkat望远镜的模拟数据对所提出的算法进行验证。
The desire for wide-field of view, large fractional bandwidth, high sensitivity, high spectral and temporal resolution has driven radio interferometry to the point of big data revolution where the data is represented in at least three dimensions with an axis for spectral windows, baselines, sources, etc; where each axis has its own set of sub-dimensions. The cost associated with storing and handling these data is very large, and therefore several techniques to compress interferometric data and/or speed up processing have been investigated. Unfortunately, averaging-based methods for visibility data compression are detrimental to the data fidelity, since the point spread function (PSF) is position-dependent, i.e. distorted and attenuated as a function of distance from the phase centre. The position dependence of the PSF becomes more severe, requiring more PSF computations for wide-field imaging. Deconvolution algorithms must take the distortion into account in the major and minor cycles to properly subtract the PSF and recover the fidelity of the image. This approach is expensive in computation since at each deconvolution iteration a distorted PSF must be computed. We present two algorithms that approximate these position-dependent PSFs with fewer computations. The first algorithm approximates the position-dependent PSFs in the $uv$-plane and the second algorithm approximates the position-dependent PSFs in the image-plane. The proposed algorithms are validated using simulated data from the MeerKAT telescope.