Solar Coronal Magnetic Fields and Sensitivity Requirements for Spectropolarimetry Channel of VELC Onboard Aditya-L1

Abstract: Understanding solar coronal magnetic fields is crucial to address the long-standing mysteries of the solar corona and solar wind. Although routine photospheric magnetic fields (MFs) are available for decades, coronal MFs are rarely reported. Visible Emission Line Coronagraph (VELC) on board Aditya-L1 mission (planned to launch in the near future) can directly measure the MFs in the inner solar corona. This can be achieved with the help of spectropolarimetric observations of the forbidden coronal emission line centered at 1074.7 nm over a field of view 1.05 R${\odot}$ - 1.5 R${\odot}$. In this article, we summarize various direct and indirect techniques used to estimate the MFs at different wavelength regimes. Further, we summarize the expected accuracies that are required to estimate MFs using VELC's spectropolarimetry channel.