The Uhuru X-Ray Instrument

On 12 December 1970, the UHURU (SAS-A) X-ray observatory was launched into equatorial orbit with the prime mission of conducting an all-sky survey of astronomical X-ray sources with intensities of 5 × 10-5 Sco-Xl or greater. Featuring two large area proportional counter detector systems, the experiment has operated without a failure and is returning information of great interest to the scientific community. This paper will aid in understanding the scientific data by presenting the system design and performance in engineering terms. Descriptions will be presented of the signal processing, aspect determination, in-flight calibration, command and telemetry formatting systems.