GOSAT was launched along with seven other piggyback probes using the H-IIA, Japan's primary large-scale expendable launch system, at 3:54 am on 23 January 2009 UTC on Tanegashima, a small island in southern Japan, after a two-day delay due to unfavourable weather. At approximately 16 minutes after liftoff, the separation of Ibuki from the launch rocket was confirmed.