New Spectrographic Lens System

Abstract

The performance of a three·prism stellar spectrograph of the Mount Stromlo Observatory is discussed. A new spectrographic objective (relative aperture fl3·5) has been designed for the largest practicable extension of the spectral image field perpendicular to the optical axis-considering stellar spectra in the wavelength region 3900-4900 A to be recorded in good definition. The complete system specifications are indicated and the design of the spectrographic objective is described.