Monitoring of the Lyman alpha emission line of the Sun during the year 1969

The shape of the Lyman α line emitted by the whole solar disk has been measured with an experiment on board the Oso 5 satellite during the year 1969. The intensity of the line in a 100 A bandpass was measured, and the use of two resonance cells, one filled with hydrogen and the other one with deuterium, gave the intensity of the line at the center and on the blue wing with a resolution better than 0.02 A. These measurements showed that the shape of the line changes considerably with solar activity, owing to variations in intensity at the center of the line, which are much greater than on the blue wing or averaged over the whole line.