Re-determination of Phoebe's orbit

In order to improve the orbit of Phoebe, the ninth satellite of the Saturnian system, 101 new observations were made by our research team in 2003, using a CCD detector of large size ($2048\times2048$ pixels) mounted on the 1.56 m astrometric reflector at the Sheshan Station of Shanghai Astronomical Observatory. We fitted a numerical integration of its orbit to all of the collected Earth-based astrometric observations from 1904 to 2003, including the newest precise data sets from Qiao & Tang and from Peng et al. A new set of initial conditions of Phoebe has been obtained, leading to an improved orbit of this satellite.