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A modified CLEAN algorithm for radiation imaging of continuous thermal sources

In order to calibration the antenna pattern errors and baseline errors of aperture synthesis radiometers (ASRs), A modified CLEAN algorithm for radiation imaging of continuous thermal sources is presented. However, only two to seven iterations are performed in the algorithm, and the iteration solution is unstable. And the algorithm can only provide a solution close to the initial guess obtained from an inverse Fourier transform of visibilities. A modified CLEAN algorithm for radiation imaging of continuous thermal sources is proposed in this paper. The initial guess of iteration is estimated under the rule of minimum norm. The impacts of errors are greatly reduced; The spatial impulse-responses of ASRs are computed using the G matrix, so it's not necessary to measure the antenna patterns; The impact of Gibbs phenomenon are reduced by modifying the iteration process and cut-off value in the proposed algorithm. The advantages of the proposed algorithm are validated by simulation. The modified CLEAN algorithm for radiation imaging of continuous thermal sources can calibrate the antenna pattern errors and baseline errors, and greatly improve the quality of reconstructed image.