Deriving the Magnetopause Position from the Soft X‐Ray Image by Using the Tangent Fitting Approach

Imaging is one of the essential techniques to observe astronomical structures. While analyzing the observed images, it is a challenge in many scientific fields to reconstruct the 3‐D structures from 2‐D image(s). This report discusses this challenge in the context of reconstructing the structure of the Earth's magnetosphere from the X‐ray image and presents a new technique. Specifically, it finds the optimum match of tangent directions derived from the X‐ray image and the parameterized magnetopause function. We name this approach as the tangent fitting approach (TFA). TFA is further validated based on the magnetohydrodynamic (MHD) simulations of the X‐ray images with different viewing geometries. TFA enables the reconstruction of the large‐scale magnetopause from a single X‐ray image, applicable to time‐dependent situations such as cases during magnetic storms. It is also noted that TFA has a potential broader application to remote sensing data, for instance, energetic neutral atom (ENA) observations. Lastly, this new approach is compared with other magnetopause reconstruction approaches.