The atmospheric emissions photometric imaging (AEPI) experiment to be flown on Spacelab 1 is designed to study faint natural and artificial atmospheric emission phenomena. Atmospheric emissions in the spectral region 2000 A to 7500 A from two optical channels, wide angle and telephoto, are detected by an image-enhanced low-light-level TV system. A third, telephoto, optical channel images onto the photocathode of a microchannel plate photomultiplier tube having 100 discrete anodes. Photons are counted for each discrete anode, providing a direct measure of the luminosity of an object viewed by the TV telephoto lens, albeit with low spatial resolution. Detector pointing in the range +/-40°x+/-80°exclusive of restrictions due to the proximity of other experiments is provided by a two-axis gimbal made from a surplus Apollo telescope mount (MAST). The pointing stability is 1 arc min with respect to the spacecraft coordinate system for an exposure of one s, and the tracking capability is 3.5 deg - s-1 with a stability of 1 arc min. The detector and pointing system are located on the Spacelab pallet and are controlled by stored programs resident in the dedicated experiment processor located in the Spacelab module.