You searched for: “astronomical spectrograph
astronomical spectrograph (s) (noun), astronomical spectrographs (pl)
A spectroscope in which the spectra of stars and other celestial objects are recorded on photographic film.

A spectroscope is an instrument for dispersing light; usually, light in the visible range, into a spectrum in order to measure it; such as, a continuous distribution of colored light produced when a beam of white light is dispersed into its components; for example, by a prism.