An interchangeable high resolution grating can also be used that gives 1.07 angstrom per pixel dispersion, with a resolution of about 2.4 angstroms when used with the narrow slit. The spectral range is smaller, being only about 75 angstroms. This resolution is adequate to detect the Doppler shift due to the earth?s motion around the sun when carefully calibrated, and detect spectroscopic binaries.

SGS with High Res Grating Product Information Sheet