A future Japanese program in far-ultraviolet astronomy and solar physics

A design study of an ultraviolet-telescope satellite (UVSAT) has been carried out by the Japanese astronomical community. The main purpose of this satellite mission would be to investigate (i) the distribution and nature of ultraviolet sources in star clusters, galaxies, and clusters of galaxies, (ii) the physical structures of galactic nebulae, and (iii) the dynamics of stellar and galactic activity. A 60 cm, f/4 Cassegrain telescope will be launched into a semi-circular orbit of ～500 km altitude and of ～30° inclination, by an ISAS/Japan M3S-III rocket. An intensified CCD camera and/or a concave-grating spectrograph will be operated for the wavelength range λ?1200 Å. Various possible auxiliary instruments and sub-telescopes are considered.