Some observers were surprised that the detonation seemed to be silent; the sound wave arrived a few seconds later. The yield was estimated at . The cloud rose to , much higher than expected. After about eight minutes, a Canberra bomber flew through the cloud to collect samples. Along with a secondary cloud that formed between , it drifted eastward. The main cloud crossed the east coast at about 11:00 on 28 September, followed by the secondary between 12 and 18 hours later. Rain on 29 September deposited some fallout between Brisbane in Queensland and Lismore in New South Wales.