When was the tennis tournament which has 1951 Australian Championships as the 39th edition first held? 
1951 Australian Championships:  It was the 39th edition of the Australian Championships (now known as the Australian Open), the 11th held in Sydney, and the first Grand Slam tournament of the year. Australian Open:  First held in 1905, the tournament is chronologically the first of the four Grand Slam tennis events of the year – the other three being the French Open, Wimbledon and the US Open.
1905