Read the Korean court weather diary for the 1808 eruption winter
Collected the daily weather line from the Royal Secretariat Diary for three winters (1807 to 1810). The weeks after the eruption, about November 1808 to January 1809, are complete and show nothing unusual in Seoul's sky. Logged as weak evidence against an Asian or west Pacific source that would have been obvious in Korea.
How it connects
This step led us to
The Korean court saw nothing odd in the sky, November 1808 to January 1809
This step and then
Checked the Constantinople omens of May 1453 against the sky and the weather
This step came after
Tested Korean dim-Sun records as a volcano detector