High sensitivity to auroral Hα, resolution in elevation angle along a narrow band from horizon to horizon, and simplicity of components are principal features of a new automatic auroral spectrograph. Sky light reaches an all-sky convex mirror by way of an external curved slot in the vertical plane, whose calculated shape gives a flat image of uniform width. This slit image of adjustable width is photographed from above by a standard 16-mm camera with f/0.95 lens, the light having passed through a blazed grating at minimum deviation. In this arrangement distortions in the noncollimated beam and losses by reflection are kept low, and slit adjustment to 25-A resolution enhances detection of the broadened Hα emission line. Satisfactory sensitivity to major airglow lines, hydrogen, and auroral features is obtained in successive 15-min exposures, representing an approximately fivefold improvement in time resolution over that of the IGY patrol spectrograph, with a consequent loss in spectral resolution.
© 1959 Optical Society of AmericaFull Article | PDF Article
OSA Recommended Articles
William A. Rense and T. Violett
J. Opt. Soc. Am. 49(2) 139-141 (1959)
Arnold M. Bass and Karl G. Kessler
J. Opt. Soc. Am. 49(12) 1223-1225 (1959)
J. Opt. Soc. Am. 49(5) 460-465 (1959)