CREATE TABLE table_1560 ("No. in series" TEXT, "No. in season" TEXT, "Title" TEXT, "Directed by" TEXT, "Written by" TEXT, "Original air date" TEXT, "Production code" TEXT, "U.S. viewers  ( millions ) " TEXT)

Name the original air date for number in season being 13
SELECT "Original air date" FROM table_1560 WHERE "No. in season" = '13'
SELECT "Original air date" FROM "table_1560" WHERE "No. in season" = '13'