The Observation of Solar Granulation from A Manned Balloon: I. OBSERVATIONAL DATA AND MEASUREMENT OF CONTRAST

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Abstract
There appears to be a practical limit to the resolution attainable in solar photography from a ground station. In an attempt to obtain greatly improved resolution, photographs have been made with a 29 cm refracting telescope mounted underneath the nacelle of a maimed balloon at a height of 18 000 ft. Two flights were made; during the second flight on 1957 April 1, 480 frames were exposed. Although the ground seeing during the flight was very poor, the photographs taken with the balloon-borne telescope during this second flight are superior to the best that have been secured at any ground station. The complex structure of the photosphere is illustrated by photographs. Autocorrelation curves for two scans across the best photograph are given. The contrast transmission functions for the complete telescope (objective, eyepiece, photographic emulsion) have been measured using sinusoidal gratings, and the results used to correct microphotometric measurements of contrast. The corrected mean contrast between granules and intergranular regions is 40 per cent at a wave-length of 5300 A.

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