Tidal correction.During the day, the Sun and Moon position relative to the observation point changes and this brings to the alteration of gravitational attraction which causes by those bodies. Due to the alteration of the gravitational attraction of Sun and Moon in the solid part of Earth, there are generating tidal effects with amplitude of 0.25 m. The influence of solar-lunar attraction considers by considering the special correction. The peak correction for Sun attraction accounts for about 0.01mGal, for Moon is 0.25mGal.