Determination of motion parameters of ISS by use of GPS measurements

We estimate the accuracy of determining the weakly disturbed orbital motion of International Space Station by use of GPS-measurements as well as the accuracy of forecasting such a motion. The measurements are the station coordinates in Greenwich coordinate system. They are received from on board equipment ASN-2401. The mean square errors of approximation of the measurements do not exceed 30 m when the motion is determined in a time interval less than a day. Processing the GPS-measurements in three-hour interval allows making the forecast of the motion on 15 hours forward with an error in the station radius vector not exceeding 400 m at a right choice of ballistic coefficient. Systematic errors in measurements of the station velocity, carried out by equipment ASN-2401, are revealed.