Spectrographs
A Spectrograph is an instrument that separates light into a frequency spectrum and records the signal using a camera. Spectrographs are used to measure the spectrum of electromagnetic radiation, including visible light, which radiates from stars and other hot celestial objects. Spectroscopy can be used to derive many properties of distant stars and galaxies, such as their chemical composition, temperature, density, mass, distance, luminosity, relative motion, etc.
