The sigma mission on the granat satellite

Abstract The soviet spacecraft GRANAT, to be launched in july 1989, will carry seven experiments dedicated to the hard X-ray/Low energy gamma ray astronomy. After a brief description of the mission and of the overall flight hardware, we shall focus on the SIGMA experiment. This french telescope designed to obtain high sensitivity images of the sky in the 30 – 1300 keV energy range will be extensively described. The main scientific objectives of the instrument will also be discuss.