EXIST

Energetic X-ray Imaging Survey Telescope

This webpage is being kept for archival purposes only.
It may be updated in the future, but it is not currently being maintained.

EXIST Free Flyer

EXIST Free Flyer with CenA in the background.

EXIST would include 3 large area (2.7 m2 each) coded aperture telescopes each with field of view 60° x 75°, for a combined total detection area of 8 m2 and field of view 180° x 75°. The 180° "fan beam" is oriented perpendicular to the orbital direction so that the full sky is imaged each orbit. Any given source is observed for at least 20% of the time, with sources closer to the orbital poles having correspondingly longer exposures. The EXIST survey sensitivity is a factor of ~1000 greater than the only previous full-sky, but non-imaging survey (HEAO-A4; 1979).

A Few Overview Figures

Wide axis of fan beam (180° x 75°) is perpendicular to scan direction, so whole sky is swept out over one orbit. View of 9 sub-telescopes. Within the Delta IV shroud.
Est. BG spectra (J. Hong). Major components are cosmic diffuse, cosmic rays, and spallation. Full-array BG rate ~25000 cts/s. Sensitivity of EXIST and other surveys.
Sensitivity vs energy for 3 telescopes. "20° x 25°" should read "180° x 75° fully coded". Approximate 1-day coverage plotted in Galactic coordinates. Exposure is greatest at orbital poles. This is for the ISS orbit, with inclination ~52°, which smoothes out much of the nonuniformity.