We describe a concept of a satellite imaging spectrometer dedicated for monitoring of the Earth atmosphere operating in the visible and near ultraviolet spectral range. The instrument targets measurements of total ozone as well as other gases (nitrogen dioxide, oxygen and its dimer etc). The instantaneous field of view (IFOV) across track reaches 100° allowing to obtain global daily maps of trace gases content when operating from a typical orbit. The optical concept and design of the instrument, which consists of the entrance unit, two spectrometric channels (for two wavelength ranges) and the calibration unit are described. We also discuss the results of the optical modeling, confirming the proposed characteristics: The spectral resolution of 0.3 nm for the range 300-400 nm and 0.5 nm for the range 400-800 nm. The angular resolution is ∼ 0.5° in both channels that corresponds to ∼6×6 km area on the Earth surface for nadir direction from a 700-km orbit.