Multi Mode Cassegrain Spectrometer of telescope Zeiss-2000 at Terskol Peak observatory

The paper presents a detailed description of a Multi Mode Cassegrain Spectrometer (MMCS) of the 2 meter telescope at Terskol Peak. A feature of the spectrometer is its modular structure, which allows (during a single observational night) mode-to-mode switching. Four spectral modes are implemented in the optical waveband on this spectrometer: prism option (R = 100), classic option (R = 1500), quasi-echelle mode (R = 5000), echelle mode (R = 13500). In all these modes, a penetrating power is close to the theoretical limiting stellar magnitude with the signal-to-noise ratio greater than 10. We describe details of the spectrometer design, characteristics of various modes, examples of obtained spectra and some astrophysical problems that can be solved with this instrument.