Thesis (M.Sc.)--Chulalongkorn University, 2001

The orbital determination of planets Jupiter and Mars is performed using Gauss method. From the photographs of the planets taken on Earth, the observational data comprising of time, right ascension and declination is obtained via the method of dependence. In Gauss method, three sets of the observational data are then processed numerically using the universal formulations subject to dynamic and geometric constraints to obtain the position and velocity of Jupiter and Mars at a given epoch time. Moreover, these position and velocity components are transformed to six orbital constants known as the classical elements which describe the planetary orbit in space. Our results agree very well with the astronomical almanac. Our computer program developed in this thesis can also be used in the orbital determination of other planets and comets.