Echelle-spectrographs for the UV-astronomy

In the middle 1990s, the Soviet Union plans to launch an orbital 1.70-m telescope for UV observations, which will contain a double echelle spectrograph with two detectors, for 1100 to 1955 A (VUV) and for 1945 to 3500 A (UV), respectively, making it possible to conduct simultaneous measurements of the whole spectral range. For order sorting, the UV spectrograph uses a prism, while the VUV spectrograph uses a concave grating. The spectrographs are coupled by moving one of the two collimator mirrors in front of the other. The space telescope is expected to reach a resolving power of 60,000.