A fully microprocessor controlled payload for hard X-ray detection.

This paper describes a completely microprocessor-controlled payload for hard X-ray astronomy that will fly on board a transatlantic balloon in the summer of 1978. The X-ray detectors are two high pressure proportional counters, filled with xenon and mounted on a stabilised platform to scan galactic and extragalactic sources. A fluxgate magnetometer and a star sensor act as the rough and the fine pointing sensors, and two INTEL CPU's (8085 and 8080) handle the data acquisition, the attitude control, the telemetry interfacing and the housekeeping of the system.