Table schema:
CREATE TABLE table_name_98 (right_ascension___j2000__ VARCHAR, constellation VARCHAR, ngc_number VARCHAR)

Question: Which Right ascension (J2000) has a Constellation of mensa, and an NGC number larger than 2171?
SQL: SELECT right_ascension___j2000__ FROM table_name_98 WHERE constellation = "mensa" AND ngc_number > 2171