CREATE TABLE table_name_24 (date_of_vacancy VARCHAR(255), team VARCHAR(255), date_of_appointment VARCHAR(255))
What is the date of vacancy of team fc bayern munich, which had a date of appointment on 27 April 2009?
    
SQL: SELECT date_of_vacancy FROM table_name_24 WHERE team = "fc bayern munich" AND date_of_appointment = "27 april 2009"