This paper discusses an attempt to detect the impact of fragment A of the comet Shoemaker-Levy 9 on Jupiter using the Doppler effect. We give a short description of the technique used to observe the impact, then present the observations along with a tentative theoretical analysis and interpretation. The instrumentation used is an advanced and more sensitive version of the Magneto-Optical Filter (normally used in Helioseismology to detect global oscillations of the Sun) and a 40 cm aperture telescope. The observed signal in July 16 (fragment A) consists of a pair of transients that, if related to the comet impact, could be interpreted as the signature of an expanding perturbation. We present only the first step of the theoretical analysis simulating a wave pulse expanding radially from the impact site. The result is remarkable in that it reproduces the two peaks although with much lower amplitudes than observed. Furthermore, the inferred particle speed is in the range 5--20 km/s which is more consistent with the plume and debris material expansion speeds derived from the HST observations and/or with shock wave propagation away from the impact site. ¿ American Geophysical Union 1995