GLONASS (Global Navigation Satellite System) Constellation is a Russian satellite navigation system that provides real-time position and velocity determination for military and civilian users. The GLONASS satellites operate in circular orbits at an altitude of 19,100 Km, an inclination of 64.8 degrees, and each satellite completes the orbit in approximately 11 hours and 15 minutes. This means that for a stationary observer, the same satellite is visible at the same point in the sky every eight sidereal days, and with eight satellites in each orbital plane, satellite positions in the sky get repeated each day (although by different satellites).