INTEGRAL: 20 years of hard X-ray surveys and Background measurements

The INTEGRAL hard X-ray surveys have proven to be of fundamental importance. In more than twenty years of operation, the INTEGRAL observatory has given us a sharper view of the hard X- ray sky, and provided the triggers for many follow-up campaigns from radio frequencies to gammarays. In addition to conducting a census of hard X-ray sources across the entire sky, INTEGRAL has carried out unique observations of the Galactic X-ray background and large-scale cosmic X-ray background, which will without question be included in the annals of X-ray astronomy as one of the mission’s most salient contribution to our understanding of the hard X-ray sky.