user: Question: Name the object type with an NGC number more than 6638 and right ascensions being 18h25m37.8s
Columns: ['NGC number', 'Object type', 'Constellation', 'Right ascension ( J2000 )', 'Declination ( J2000 )']
Types: ['real', 'text', 'text', 'text', 'text']
Sample row: [6601.0, 'Galaxy', 'Draco', '18h11m44.3s', '°27′12″']
SQL:

assistant: SELECT "Object type" FROM "Table" WHERE "NGC number" > 6638.0 AND "Right ascension ( J2000 )" = '18h25m37.8s';