CREATE TABLE table_name_57 (ngc_number INT, right_ascension___j2000__ VARCHAR)

Tell me the highest NGC number for right ascension of 09h40m28.5s
SELECT MAX(ngc_number) FROM table_name_57 WHERE right_ascension___j2000__ = "09h40m28.5s"
SELECT MAX("ngc_number") FROM "table_name_57" WHERE "09h40m28.5s" = "right_ascension___j2000__"