Rocket Spectra of the Chromosphere

Abstract

Photographic or photoelectric recordings of solar XUV-spectra* at wavelengths from about 1 700 Å to 1 Å can be well-obtained only from altitudes above those reached in mountaintop or even balloon experiments. Therefore, the history of the experimental art of acquiring such spectra begins no sooner than the scientific use of rockets around 1946. Actual spectral resolution of solar emission lines at wavelengths below about 2200 Å, however, was accomplished for the first time about six years later. This accomplishment had to await the successful development of a servomechanism for fairly accurate solar pointing of spectrographs during the high altitude portion of the rocket flight. This development is due to the work of W. A. Rense and W. B. Pietenpol and their associates (University of Colorado). In 1952 they obtained the first spectrophotographic evidence (W. A. Rense, 1953) of the solar hydrogen Lyman alpha line, recovering the record from a grazing incidence grating spectrograph kept properly oriented in a biaxial solar pointing control mounted on an Aerobee rocket.