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The spectral resolution of a spectrograph, or, more generally, of a frequency spectrum, is a measure of its ability to resolve features in the electromagnetic spectrum. It is usually denoted by , and is closely related to the resolving power of the spectrograph, defined as , where is the smallest difference in wavelengths that can be distinguished at a wavelength of . For example, the Space Telescope Imaging Spectrograph (STIS) can distinguish features 0.17 nm apart at a wavelength of 1000 nm, giving it a resolution of 0.17 nm and a resolving power of about 5,900. An example of a high resolution spectrograph is the ''Cryogenic High-Resolution IR Echelle Spectrograph'' (CRIRES) installed at ESO's Very Large Telescope, which has a spectral resolving power of up to 100,000.〔(- CRIRES Instrument page at ESO )〕 ==Doppler effect== The spectral resolution can also be expressed in terms of physical quantities, such as velocity; then it describes the difference between velocities that can be distinguished through the Doppler effect. Then, the resolution is and the resolving power is where is the speed of light. The STIS example above then has a spectral resolution of 51 km/s. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「spectral resolution」の詳細全文を読む スポンサード リンク
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