Correcting false structures in solar deep-integration magnetogram observations

The real-time correlation solar observation system with a deep integration technique has been operating since 2012 at the Huairou Solar Observation Station at the National Astronomical Observatories of China.However,some magnetograms show false granular structures.After analyzing these images,we believe that the false structures are generated in the last step of the magnetic field measurement:the subtraction of the right circular polarized accumulation image from the left one.Since the left or right image is aligned with the first or second frames by a shift and add technique,separately;the intensity difference between the fields of view(FOV) of the first and second frames cause the false structures.We propose a correction method.Two average FOVs of circular polarized accumulation images are selected as the reference images to replace the first and second frames.Since the average FOVs are determined by the displacement which was calculated and recorded during the alignment procedure,this method can be easily implemented in routine observation procedures.The experimental results prove that our method is successful and effective.