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  • Allen, Branden; Hong, Jaesub; Grindlay, Josh; Barthelmy, Scott D; Baker, Robert G; Gehrels, Neil A; Garson, Trey; Krawwczynski, Henric S; Cook, Walter R; Harrison, Fiona A; Apple, Jeffery A; Ramsey, Brian D

    arXiv.org, 09/2010
    Paper, Journal Article

    {\it ProtoEXIST1} is a pathfinder for the {\it EXIST-HET}, a coded aperture hard X-ray telescope with a 4.5 m\(^2\) CZT detector plane a 90\(\times\)70 degree field of view to be flown as the primary instrument on the {\it EXIST} mission and is intended to monitor the full sky every 3 h in an effort to locate GRBs and other high energy transients. {\it ProtoEXIST1} consists of a 256 cm\(^2\) tiled CZT detector plane containing 4096 pixels composed of an 8\(\times\)8 array of individual 1.95 cm \(\times\) 1.95 cm \(\times\) 0.5 cm CZT detector modules each with a 8 \(\times\) 8 pixilated anode configured as a coded aperture telescope with a fully coded \(10^\circ\times10^\circ\) field of view employing passive side shielding and an active CsI anti-coincidence rear shield, recently completed its maiden flight out of Ft. Sumner, NM on the 9th of October 2009. During the duration of its 6 hour flight on-board calibration of the detector plane was carried out utilizing a single tagged 198.8 nCi Am-241 source along with the simultaneous measurement of the background spectrum and an observation of Cygnus X-1. Here we recount the events of the flight and report on the detector performance in a near space environment. We also briefly discuss {\it ProtoEXIST2}: the next stage of detector development which employs the {\it NuSTAR} ASIC enabling finer (32\(\times\)32) anode pixilation. When completed {\it ProtoEXIST2} will consist of a 256 cm\(^2\) tiled array and be flown simultaneously with the ProtoEXIST1 telescope.