How many letters does the top answer for “discovered or determined by scientific observation” have?

The most common answer is ascertained (11 letters).

Crossword clue: discovered or determined by scientific observation

2 answers found in Letterora's clue database (Wikidata facts, Open Trivia DB, WordNet and Webster definitions — all licensed sources).

ascertained 11 letters wn-def

discovered or determined by scientific observation

observed 8 letters wn-def

discovered or determined by scientific observation