An echelle spectrograph is a specialized instrument used in astronomy to disperse and analyze the light emitted or absorbed by celestial objects. It is designed to achieve high spectral resolution, allowing astronomers to study the detailed composition, temperature, velocity, and other characteristics of stars, galaxies, and other astronomical objects. The key feature of an echelle spectrograph is its ability to disperse light into its component wavelengths using a diffraction grating. It utilizes a combination of two gratings: a coarse grating disperses the light in the horizontal direction, while a finer echelle grating disperses it in the vertical direction. This arrangement results in a high level of dispersion, enabling the separation of closely spaced spectral lines, even in high-resolution spectra.