During the Apollo-Soyuz Test Project, an extreme-ultraviolet photometer with a cyclically operated helium gas absorption cell observed the daytime sky from an orbital altitude of 225 km. When the line of sight pointed more than 60¿ from the Sun, the instrument detected 2 to 70 rayleighs of flux scattered from neutral geocoronal helium at wavelengths from 504 to 584 ¿. The instrument also detected other radiation in the band 500-700 ¿ of similar spatial distribution to the helium flux, which was definitely not due to the He I 584 ¿ spectral line, and which has not been detected by previous experimenters in data from 400 km altitude. Possible sources of this radiation are discussed.