Photometric techniques in mutual events of Galilean satellites

The photometry of mutual occultations and eclipses of Galilean satellites of Jupiter can be used to deliver very accurate astrometric information, which can be further used for improvement of the dynamical models and their ephemerides of the concerned satellites. The photometry of the CCD images of mutual occultations and eclipses of Jupiter's satellites which were observed at Yunnan Observatory in 2003 was done and light curves in different situations were obtained. From the light curves, the midlight time and the decline magnitude can be obtained. It is found that the light curves will be stable when the halo around the Jupiter is removed and the photometric apertures are assigned between 1.5 and 2.0 times of FWHM of satellite's image.