Deriving the magnetopause position from wide field-of-view soft X-ray imager simulation

Imaging techniques provide essential information in astronomical and space physics studies.The Soft X-ray Imager(SXI)will obtain images of the Earth’s magnetosphere via the solar wind charge exchange process in a global view.However,it is a challenge to reconstruct its 3-D structures from the observed 2-D image(s).In this paper,a recently proposed method,Tangent Fitting Approach(TFA),is validated to reconstruct the large-scale magnetopause from a single X-ray image obtained by instrument simulation.It is revealed that the large-scale magnetopause under a medium solar wind number density can be well reconstructed,although the locations of maximum X-ray photon counts are scattered in the image due to instrumental effects and diffusive sky background.Higher solar wind number density leads to stronger signals and further leads to better reconstruction results.For lower solar wind density,the X-ray maximum photon counts may not be identified from the SXI simulations,preprocessing of the images shall be considered before applying TFA.Furthermore,the subsolar magnetopause can be well derived when the satellite is on the dayside orbits.