Welcome to the ProtoEXIST web site at CfA

ProtoEXIST is a balloon-borne wide-field hard X-ray survey project, which is a prototype experiment for a next generation hard X-ray survey mission - the Energetic X-ray Imaging Survey Telescope (EXIST). EXIST was recommended by the 2001 Decadal Survey and further developed as a candidate for Black Hole Finder Probe (BHFP) under the NASA Beyond Einstein program and then for the 2010 Decadal Survey. Although not recommended (on cost grounds) by the Astro2010 Survey, the science objectives and capabilities of EXIST are consistent with priorities recommended in the Astro2010 Survey Report and Panel Reports. A Hard X-ray (5-100 keV; with response to 200 keV) imaging survey of at least half the sky is needed for 1) A high resolution (5X finer than Swift/BAT) survey of the Galactic Bulge and full southern galactic plane to locate transients, obscured black holes and Ti-44 sources for followup with NuSTAR and Astro-H, 2) Time Domain Astrophysics studies of the Bulge, southern Plane and North Galactic Pole with coverage each 96min orbit, and 3) Broader-band, higher spatial resolution studies of GRBs, with identification of Advanced LIGO short GRBs as well as novel opportunities for ground-based 24h coverage of southern-sky GRBs. ProtoEXIST2 (P2) is a technology development pathfinder for the proposed (Mission of Opportunity under the Explorer Program) Hard X-ray Imager (HXI) for the MIRAX-HXI mission. P2/HXI is currently being developed at CfA along with key collaborators at Caltech, NASA GSFC, and (for our balloon gondola) at NASA MSFC. The MIRAX-HXI mission is planned for launch by Brazil in 2016. Please direct any questions or comments on the website to