Liam Edwards

Total eclipses provide a unique opportunity to observe the solar corona over a short period of minutes. A white-light optical system designed and built by a team from Aberystwyth University was used to make polarized brightness (pB) observations of the corona during the Argentinian total solar eclipse of December 2020. The pB images enable the separation of the light produced by dust (the F-corona) from the light emitted by electrons in the plasma of the corona (the K-corona). The K-corona observations allow us to determine the density of the plasma, which is central to understanding the balance of forces in the solar atmosphere. The instrument was called the “Coronal Imaging Polariser” (CIP: in Welsh “cip” means a quick look). Due to Covid-19, and the poor weather in South America at the time, the Aberystwyth team were lucky to gather successful scientific observations during this eclipse. CIP works by automatically rotating a polarizer to six polarization angles (0, 30, 60, 90, 120, and 150 degrees) and takes five different exposures at each angle (0.001s, 0.01s, 0.1s, 1s, and 3s), enabling a precise measurement of the polarization of the strong light from the lower corona, as well as the fainter outer corona. I will present a brief description of the calibration and image processing methods, present some preliminary results, and summarize what we hope to achieve with this data.