user: Question: What's the longitude named Zipaltonal Fluctus in 1997 with a diameter smaller than 490?
Columns: ['Name', 'Latitude', 'Longitude', 'Diameter (km)', 'Year named']
Types: ['text', 'text', 'text', 'real', 'real']
Sample row: ['Alpan Fluctus', '7.5S', '349.0E', 500.0, 1997.0]
SQL:

assistant: SELECT "Longitude" FROM "Table" WHERE "Year named" = 1997.0 AND "Diameter (km)" < 490.0 AND "Name" = 'Zipaltonal Fluctus';