Airglow and star photographs in the daytime from a rocket.

Photographs of the constellation Cygnus taken in the daytime from altitudes above 100 kilometers indicate that the day sky brightness in the wave-length region from 3600 to 7000 angstroms is only slightly brighter than the night sky viewed from the ground. No diffuse cloud of particles was apparent in the vicinity of the rocket payload, but discrete particles must be considered in the design of instruments for rockets and satellites. The resultant data and reports of star sightings from manned spacecraft indicate similar optical environments for both types of vehicles, that is, discrete particles and relatively low levels of background brightness, only slightly brighter than the night sky as an upper limit.