Data Processing And Analysis Of Observed Light Curves Of Occultations Of Galilean Satellites

There are two ways of astrometric research in the image processing of astronomical images.One is to obtain the measured coordinates of the celestial objects directly, and then thesemeasured coordinates are compared with their catalogues or ephemerides. Another way is tomeasure the brightness of two concerned occulted or eclipsed celestial objects, and extractspositional information after reduction. Meanwhile, the data of mutual events is very precioussince it does not occur frequently. The second way has usually higher precision.The work in this paper is to do some further processing on the basis of flux-changinglightcurves using the moving model of two concerned satellites proposed first by Noyelles andVienne. We attempt to do the processing by constructing a data processing system throughcomputer programming. We apply the least-square fitting and iteration to the satellites’ movingmodel to solve some parameters and the relative positions of the satellites, and then compare theresults with those from an ephemeris, and thus deriving (O-C)(Observed minus Computed)residual.The preliminary experimental results show that most derived residuals are in the smallrange with two of them exceptional. By analyzing the two sets of abnormal residual data, we findthat the accuracy of the ratio of the geometric albedos for the two concerned satellites has a greatinfluence on the relative position of the satellites. As such, an improved algorithm is designedand performed, and better results have been derived. Finally, we come to the conclusion on theexperiment that very small (O-C) s of less than0.1arcsec have been derived for almost allobservations and the feasibility and reliability of our data-processing system are confirmed whenprocessing the observations of mutual occultation.The data-processing system can be used to solve the similar observed light curves ofoccultations of natural satellites in future.