The Cotton-Schwab Clean At Ultra-High Dynamic Range |
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Authors: | M A Voronkov M H Wieringa |
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Institution: | (1) CSIRO Australia Telescope National Facility, Locked Bag 194, Narrabri, 2390, NSW, Australia |
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Abstract: | We present a study of the dynamic range limitations in images produced with the proposed Square Kilometre Array (SKA) using
the Cotton-Schwab CLEAN algorithm for data processing. The study is limited to the case of a small field of view and a snap-shot observation. A new
modification of the Cotton-Schwab algorithm involving optimization of the position of clean components is suggested. This
algorithm can reach a dynamic range as high as 106 even if the point source lies between image grid points, in contrast to about 103 for existing CLEAN-based algorithms in the same circumstances. It is shown that the positional accuracy of clean components, floating point
precision and the w-term are extremely important at high dynamic range. The influence of these factors can be reduced if the variance of the
gradient of the point spread function is minimized during the array design. |
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Keywords: | techniques: interferometric techniques: image processing methods: numerical |
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