The profile of solar hydrogen-Lyman-α

The profile of the Lyman-α line of hydrogen in the radiation from the sun was determined using a photographic spectrograph, flown in an Aerobee-High rocket on July 21, 1959, as a part of the United States effort in the International Geophysical Cooperation, 1959. The instrument employed a 50-cm radius, 1200 I/mm diffraction grating in the 13th order, following a design originated by Dr. Robert J. Meltzer of the Bausch and Lomb Optical Company. Overlapping orders and stray light were effectively eliminated by means of a similar grating as a predisperser; this grating was used at an angle of incidence such that the optical system as a whole was stigmatic. Therefore, points along the spectrum line corresponded to points in a narrow slice diametrically across the sun.