Correction of solar dopplergrams' large-scale flatfield

I. A. Patrikeev^a, G. P. Mashnich^b, A. I. Khlystova^b, H. Zhang<sup>c

a</sup> Institute of Continuous Media Mechanics UB RAS, Perm
^b Institute of Solar-Terrestrial Physics, Irkutsk
^c National Astronomical Observatories of the Chinese Academy of Sciences

Abstract: The authors have proposed and compared three different methods of large-scale flatfield correction (time averaging, Fourier filtering, and wavelet-based filtering). As an example, the real dopplergram of the velocity field in a solar active region obtained at the Huairou Solar Observing Station of National Astronomical Observatories of China has been processed. It is shown that any of the applied methods can improve the visual quality of the image. A quantitative comparison of the proposed methods was performed by evaluating the heterogeneity of the images.

Keywords: wavelet-based methods; filtering; data analysis.

UDC: 520.88