SOLSTICE II, the solar stellar irradiance comparison experiment on EOS

The SOLSTICE II instrument on EOS, a device that measures the solar irradiance in the spectral interval 115 to 440 nm and is capable of detecting solar variability on all time scales with an accuracy of better than 1 percent, is presented. It is capable of relating the solar output to the UV radiation coming from a number of bright blue stars whose output should be extremely stable over time periods of thousands of years. The ratio of the solar flux to the ensemble average stellar flux as measured during the EOS era can be directly compared to similar measurements made at any other time. The SOLSTICE instrument on UARS is to obtain such observations for a period of perhaps 10 yr starting in October 1991.