Abstract :
Satellites have a path called an orbit. Satellites orbiting in stationary orbit have LEO, MEO, GEO. A satellite in a geostationary orbit will have a relatively slow speed so that a perturbation will occur. The perturbation is an external disturbance resulting from a third object. Therefore, a method is needed to predict the path traversed by the satellite. By knowing the satellite is in the instantaneous position and velocity, two methods that can explain the prediction of the orbital path are the Cowell’s method and the Encke’s method. These two orbital methods have distinct advantages and disadvantages, so that in this study a comparison of the two methods is used to determine the time interval when satellite orbits are displaced. Based on ITU-R Rec. S.484, the satellite has a tolerance limit of ± 0.5° to monitor the satellite displacement area. When the satellite leaves the surveillance area, the ground and spacecraft segment will change. Therefore, it is necessary to predict the time interval of orbital displacement using the Cowell’s method and the Encke’s method. The research was conducted using quantitative methods referring to Telkom 4 satellites observations in geostationary orbit. The results of the research show that the Cowell’s method can explain the orbital displacement time interval, ranging from 23 hours 56 minutes while the Encke’s method can explain the effect of changes in orbital position displacement on Telkom 4 satellites in geostationary satellites. The benefit of research is to provide knowledge and consideration to earth stations in predicting the time intervals of orbital displacements that occur. Keywords: Satellite, Orbit, Cowell’s Method, Encke’s Method