Verification pass
Ten web searches on every row marked VERIFYING or OPEN, then fetched the key papers. Lists of unsolved mysteries go stale fast: the 1181 supernova and the 1831 eruption were both solved in the last five years.
How it connects
This step led us to
1458 eruption pair two eruptions
This step led us to
1808 mystery eruption still open
This step led us to
1831 mystery eruption found solved
This step and then
Pulled the table the search engines could not see
This step came after
Started the notebook