CREATE TABLE table_21974 ("Episode" TEXT, "Broadcast date" TEXT, "Run time" TEXT, "Viewers  ( in millions ) " TEXT, "Archive" TEXT)

What is the broadcast date when 8.3 million viewers watched?
SELECT "Broadcast date" FROM table_21974 WHERE "Viewers (in millions)" = '8.3'
SELECT "Broadcast date" FROM "table_21974" WHERE "Viewers (in millions)" = '8.3'