German-Russian cooperation in helioseismology

At the end of the 80th the cooperation of German and Russian scientists started in the area of helioseismology with the development of the DIFOS experiment. This device measured the fluctuations of the total irradiance of the Sun in 3 spectral channels. The results of DIFOS-P showed the correctness of the technical approach. Based on the experiences of DIFOS-P the follower device DIFOS-M with enhanced capabilities was developed. This new device covers 6 spectral channels and will be launched with KORONAS-F in 1999. For the future, the next generation experiment GROSSE is planned. This device will be capable to make images in 3 spectral channels (190 nm, 550 nm, 1650 nm). The main goal of this new experiment is the measurement of the limb darkening function of p-modes at different wavelengths.