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Session 71 - Space Astronomy in the Next Millennium.
Display session, Wednesday, January 17
North Banquet Hall, Convention Center
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We describe our study of a New Mission Concept to carry out the first high sensitivity imaging survey of the entire sky at hard x-ray energies (10-600 keV). The Energetic X-ray Imaging Survey Telescope (EXIST) would include 2-4 large area coded aperture telescopes with offset fields of view (20\deg \times 80\deg, total) and conduct a 1 year all sky Survey with total exposures of \ga500 ksec and flux sensitivities below 1 mCrab with time resolution from msec to months for each source as well as high spatial and spectral resolution for sources, transients and gamma-ray bursts. A pointed Observatory phase would follow and achieve still greater sensitivities and temporal coverage, allowing the detailed study of virtually all classes of accretion sources (cataclysmic variables to quasars) as well as diffuse emission. EXIST would achieve all-sky sensitivities some 100\times greater than the only other (non-imaging) all-sky hard x-ray survey performed (1978-79) by the HEAO-1 (A3) mission. At 100 keV, the all-sky sensitivity would be \sim10\times greater than achieved by XTE in 1\deg \times 1\deg in a \sim 2 day exposure and \sim10\times more sensitive for line emission than OSSE. Gamma-ray bursts would be detected with 10\times the sensitivity of BATSE and located to \la30\arcsec. The imaging detector system for EXIST is a modularized array of Cd-Zn-Te crystals with 2500 cm^2 total detector area and 3 mm spatial resolution for each telescope to provide 14\arcmin angular resolution and \sim4-6 keV energy resolution imaging. A brief description of the proposed detector and telescopes, predicted backgrounds and sensitivity, and requirements for supporting spacecraft is given together with details of the Survey and Observatory mission phases. EXIST is under review for possible selection in the NASA/MIDEX program and, with its wide-field and multiplexed source observing, would enable a wide range of Guest Investigator programs.
