MOTION OF COMET-D SHOEMAKER-LEVY-9 BEFORE THE BREAKUP

We collected astrometric observations of 19 fragments of the comet to determine separate orbits for 19 comet's nuclei. All the computations have been carried out in jovicentric rectangular coordinates; we inclu ded the solar and planetary perturbations, the perturbations due to ob lateness of Jupiter and due to the Galilean jovian satellites. All the nuclei passed through the perijove almost simultaneously in 1992 July 7.8 at a distance amounting to 1.3 of Jupiter's equatorial radii. We assumed that motion of the center of mass of the comet's nuclei may re present the motion of the comet before its breakup near Jupiter in Jul y 1992. We used values of diameters published for all the fragments of the comet to estimate relative masses of the nuclei, and accepted an earlier published result according to which the comet was disrupted 2. 2 hours after its perijove time. We computed coordinates and velocity components for the center of mass of the nuclei, and thus we found the jovicentric orbit of the comet's parent body for 1992 July 7.921 ET. Equations of the jovicentric motion of the comet have been integrated back to 1990 Jan. 29 when the comet was about 1 a.u. from Jupiter, men the jovicentric hyperbolic orbit was transformed to the heliocentric one. We got the following elements of the osculating heliocentric orbi t of the comet:[GRAPHICS] We investigated the heliocentric motion of t he comet before 1992. Evolution of jovicentric and heliocentric trajec tories of the comet is presented graphically.