question: When did the investigation of the signals transmitted by Compass - M1 begin ?
answer: immediately after the launch of Compass - M1 on 14 April 2007
turker_answer: The investigation of the signals transmitted by Compass - M1 began in immediately after the launch of Compass - M1 on 14 April 2007 .
rule-based: The investigation of the signals transmitted by Compass - M1 began in immediately after the launch of Compass - M1 on 14 April 2007 .