GRAPH SPECTRAL CLUSTERING OF CONVOLUTION ARTEFACTS IN RADIO INTERFEROMETRIC IMAGES

The starting point for deconvolution methods in radioastronomy is an estimate of the sky intensity called a dirty image. These methods rely on the telescope point-spread function so as to remove artefacts which pollute it. In this work, we show that the intensity field is only a partial summary statistic of the matched filtered interferometric data, which we prove is spatially correlated on the celestial sphere. This allows us to define a sky covariance function. This previously unexplored quantity brings us additional information that can be leveraged in the process of removing dirty image artefacts. We demonstrate this using a novel unsupervised learning method. The problem is formulated on a graph: each pixel interpreted as a node, linked by edges weighted according to their spatial correlation. We then use spectral clustering to separate the artefacts in groups, and identify physical sources within them.


Presented at:
International Conference on Acoustics, Speech, and Signal Processing (ICASSP 2019), Brighton, UK, 12-17 May 2019
Year:
May 12 2019
Keywords:
Laboratories:




 Record created 2019-02-11, last modified 2019-06-19

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