Study of the Solar Coronal Data from the 8th April 2024 Total Solar Eclipse Observation Campaign

The purpose of this thesis is the data analysis of the total solar eclipse campaign of April 8, 2024, and the instrument calibration. The goal of the mission is to perform polarimetric observations of the radiation of the solar corona in the continuum and in two coronal emission lines. The polarimeter assembly of the two instruments, of which I analyzed the data, is based on Liquid Crystal Variable Retarders (LCVRs), an electro-optical element which, together with a quarter-wave plate, enables the rotation of the polarization angle of the incoming coronal radiation without requiring any moving mechanical parts. This serves as an important ground-based test for future instruments designed for spectro-polarimetry of coronal emission lines. The E-KPol instrument observed the K-corona in the continuum, allowing the investigation of the coronal morphology and the study of the coronal plasma electron density. E-CorMag performed Fe XIV, He I D3 and K-corona continuum observations by means of its three filters, with the primary goal of detecting and characterizing the presence and the orientation of the magnetic field in coronal structures. The calibration procedures were carried out at the INAF-OATo optics and electronics laboratory, involving detector characterization and the evaluation of the instruments’ optical, radiometric, and polarimetric performance. The calibration activity included the determination of the LCVRs retardances as a function of the applied voltages. Based on experimental results, the optimal modulation schemes were selected for the measurement of the coronal polarized brightness, which is due to Thomson scattering of solar photospheric radiation by coronal electrons. Data processing was carried out by using custom Python routines written by me for this thesis work. The sky conditions during the total solar eclipse were characterized by the presence of cloudy veils, hence we had to use complementary data from both ground-based and satellite instruments. For this reason, only E-KPol data analysis was completed, while the E-CorMag analysis has been only partially accomplished. The reliability of E-CorMag results needs a further analysis that is still in progress. Despite these challenges, this study provides valuable insights into coronal polarization measurements and serves as a foundation for improving future eclipse campaigns and spectro-polarimetric observations.