Scale sequentially CLEAN for Mingantu Spectral Radioheliograph
Author:
Цзюнь Чэн12, Jun Cheng34, Йихуа Йан56, Yihua Yan78, Дун Чжao9, Dong Zhao7, Лун Сюй10, Long Xu11
Affiliation:
1. Главная лаборатория исследования солнечной активности, Национальные астрономические обсерватории, Академия наук КНР 2. Государственная главная лаборатория космической пого-ды, Академия наук КНР 3. Key Laboratory of Solar Activity, National Astronomical Observatories 4. State Key Laboratory of Space Weather, Chinese Academy of Sciences 5. Главная лаборатория исследования солнечной активности, Национальные астрономические обсерватории, Академия наук КНР 6. Университет Китайской академии наук 7. Key Laboratory of Solar Activity, National Astronomical Observatories, Chinese Academy of Sciences 8. University of Chinese Academy of Sciences 9. Главная лаборатория исследования солнечной активно-сти, Национальные астрономические обсерватории Китая, Академия наук КНР 10. Национальные астрономические обсерватории Китая 11. National Astronomical Observatories of Chinese Academy of Sciences
Abstract
MingantU SpEctral Radioheliograph (MUSER) is a solar-dedicated radio heliograph, adopting aperture synthesis technique to image the Sun in the frequency range of 0.4 GHz to 15 GHz. MUSER has extremely high spatial resolution, temporal resolution, and frequency resolution beyond those of contemporary devices of the same category. For aperture synthesis, the number of antennas is limited, so sparse sampling of Fourier components is actually obtained for solar observation, which corresponds to the situation that a clean image is convolved by a dirty beam with strong sidelobe in a spatial domain. Thus, the deconvolution, such as CLEAN, is generally required for imaging the aperture synthesis to remove artifacts caused by the convolving dirty beam. The traditional Högbom CLEAN is based on the assumption that an observed object is only composed of point sources. This assumption does not hold for solar observation, where the solar disk is an extended source containing complex structures and diffuse features. In this paper, we make the first attempt to employ scale sequentially CLEAN for MUSER imaging, including Multi-Resolution CLEAN and Wavelet CLEAN. The experimental results demonstrate that the scale sequentially CLEAN, especially wavelet CLEAN, is superior to the traditional CLEAN algorithm in smaller number of iterations and improved image quality. We provide optimized wavelet parameters to further improve the performance of wavelet CLEAN.
Publisher
Infra-M Academic Publishing House
Subject
Space and Planetary Science,Atmospheric Science,Geophysics
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