Coded-aperture x-ray/gamma-ray telescope for arc-minute localization of gamma-ray bursts

MARGIE (Minute-of-Arc Resolution Gamma-Ray Imaging Experiment) will be a large-area (approx. 104 cm2), wide field-of-view (approx. 26° half-angle), hard X-ray/gamma-ray imaging telescope capable of providing accurate positions for faint gamma-ray bursts in near-real-time and of performing a sensitive survey of both steady and transient cosmic sources. The instrument is designed to image faint bursts at the low-intensity (high-redshift) end of the log N - log S distribution. MARGIE was recently selected by NASA for a mission-concept study for an Ultra Long Duration Balloon flight. We describe a program to develop an instrument based on the new detector technology of either cadmium zinc telluride room-temperature semiconductors or pixellated cesium iodide scintillators viewed by fast timing charge-coupled devices