The presence of a systematic error in SDO/HMI data

Abstract

In this paper, we came to the conclusion that there is a systematic error in SDO/HMI (Helioseismic and Magnetic Imager aboard the Solar Dynamics Observatory) vector magnetic data, which reveals itself in a deviation from the radial direction of the knot magnetic fields manifesting themselves on magnetograms in the form of small grains in a strong magnetic field. This deviation demonstrates a dependence on the distance to the disk center, which cannot be a property of the magnetic field – it can only be artificially introduced into the data. We suggest a simple method for correcting vector magnetograms, which eliminates the detected systematic error.

Keywords

• Sun
• magnetic field
• vector magnetograms