EXIST: All-Sky Hard X-ray Imaging and Spectral-Temporal Survey for Black   Holes
  The Energetic X-ray Imaging Survey Telescope (EXIST) is under study for the proposed Black Hole Finder Probe, one of the three Einstein Probe missions in NASA's proposed Beyond Einstein Program. EXIST would have unique capabilities: it would survey the full sky at 5-600 keV each 95min orbit with 0.9-5 arcmin, 10microsec - 45min, and ~0.5-5 keV resolution to locate sources to 10arcsec and enable black holes to be surveyed and studied on all scales. With 5sigma survey sensitivity (0.5-1y) Fx(40-80 keV) ~5 x 10^-13 cgs, or comparable to the ROSAT soft X-ray (0.3-2.5 keV) sky survey, a large sample (~2-4 x 10^4) of obscured AGN will be identified and a complete sample of accreting stellar mass BHs in the Galaxy will be found. The all-sky/all-time coverage will allow rare events to be measured, such as possible stellar disruption flares from dormant AGN out to ~200 Mpc. A large sample (~2-3/day) of GRBs will be located (<~10arcsec) at sensitivities and bandwidths much greater than previously and likely yield the highest redshift events and constraints on Pop III BHs. An outline of the mission design from the ongoing concept study is presented. 
Jonathan E. Grindlay (and the EXIST Team)