GSAT-8 or INSAT-4G is communication satellite. It was constructed by the Indian Space Research Organisation, as part of INSAT system. GSAT-8 was launched on May 21, 2011, from Kourou, French Guiana. The rocket, an Ariane 5 was the carrier, marketed by the European Arianespace. First satellite to carry GAGAN payload followed up by GSAT-10 and in-orbit spare GSAT-15.