user: Question: What is the Format of the September 22, 2008 release with Catalog number RTRADCD491?
Columns: ['Region', 'Date', 'Label', 'Format', 'Catalog']
Types: ['text', 'text', 'text', 'text', 'text']
Sample row: ['Australia', 'September 20, 2008', 'Rough Trade Records', 'CD', 'RTRADCD491']
SQL:

assistant: SELECT "Format" FROM "Table" WHERE "Catalog" = 'RTRADCD491' AND "Date" = 'September 22, 2008';