Published in Appl. Opt. 59 F1-F10 in 2020
G. P. Können, G. Schneider, E. H. Zucker, P. Lahtinen
A photographic observation sequence was obtained of a subsun before,
during and after the total phase of the 2016 solar eclipse. The time-resolved
images were obtained from a high-altitude jet aircraft. The image sequence was
searched for the possible presence of a solar corona-generated subsun during
totality. Although the subsun-creating conditions apparently persisted during
totality, the drop in signal intensity compared to the local background
prevented its detection. Separately, we document a visual observation from the
1977 total solar eclipse of a rainbow that faded, in the last a few seconds
before totality, from as normally multicolored to monochromatic red from water
drops then predominantly illuminated by light from the solar chromosphere. A
similar transition in the final seconds before, and after, totality are
expected occur for parhelia. The posited short-living monochromatic red
parhelion resulting from the momentary illumination of ice crystals by the
solar chromosphere is still waiting to be observed.