CREATE TABLE table_name_27 (constellation VARCHAR, right_ascension___j2000__ VARCHAR)

What Constellation has a 20h56m40s Right Ascension (J2000)?
SELECT constellation FROM table_name_27 WHERE right_ascension___j2000__ = "20h56m40s"
SELECT "constellation" FROM "table_name_27" WHERE "20h56m40s" = "right_ascension___j2000__"