user: Question: What date did the episode with 8.61 million U.S. viewers originally air?
Columns: ['№', 'Title', 'Directed by', 'Written by', 'Original air date', 'Production code', 'U.S. viewers (million)']
Types: ['real', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: [1.0, '" Pilot "', 'Alex Graves', 'J. J. Abrams & Alex Kurtzman & Roberto Orci', 'September9,2008', '276038', '9.13']
SQL:

assistant: SELECT "Original air date" FROM "Table" WHERE "U.S. viewers (million)" = '8.61';