EXIST: A high sensitivity hard x-ray imaging sky survey mission for ISS

A deep all-sky imaging hard x-ray survey and wide-field monitor is needed to extend soft (ROSAT) and medium (ABRIXAS2) x-ray surveys into the 10-100 keV band at comparable sensitivity (∼0.05 mCrab). This would enable discovery and study of (greater-or-similar sign)3000 obscured AGN, which probably dominate the hard x-ray background; detailed study of spectra and variability of accreting black holes and a census of BHs in the Galaxy; Gamma-ray bursts and associated massive star formation (PopIII) at very high redshift and Soft Gamma-ray Repeaters throughout the Local Group; and a full galactic survey for obscured supernova remnants. The Energetic X-ray Imaging Survey Telescope (EXIST) is a proposed array of 8x1 m2 coded aperture telescopes fixed on the International Space Station (ISS) with 160 degree sign x40 degree sign field of view which images the full sky each 90 min orbit. EXIST has been included in the most recent NASA Strategic Plan as a candidate mission for the next decade. An overview of the science goals and mission concept is presented