This is the flight backup to the grazing incidence photographic spectrograph used on Skylab (Experiment S020). The spectrograph was mounted in the solar airlock of the Orbital Workshop. It recorded x-ray and uv solar spectra. An astronaut employed a small telescope mounted at the side to place an image of the sun on the entrance slit of the instrument. A thin metallic film blocked visible sunlight allowing uv and x-ray energy through to a large diffraction grating at a very shallow grazing angle. The resulting dispersed spectrum was recorded on photographic film. Dr. Richard Tousey of the Naval Research Laboratory was the Principal Investigator for this experiment. The instrument was transferred from NASA's Johnson Manned Space Center in 1982.