STRATOSPHERIC WIND SPEEDS FROM AN IR IMAGE-ANALYSIS OF THE SL-9 IMPACT REGIONS ON JUPITER

The effects of comet Shoemaker-Levy-9's impacts on Jupiter were imaged from 16 July to 26 July 1994 through 1500 nm, 1580 nm, 1700 nm and 23 00 nm filters with the 3.5 m telescope + MAGIC camera at the Calar Alt o Observatory, Spain. The pixel resolution of 0.32 '' corresponds to a bout 1200 km at the sub-Earth-point on Jupiter. Good weather condition s enabled excellent time coverage of the event. An unsharp masking ima ge technique was applied to the images as a high-pass filter in order to enhance the impact spot structures. For the analysis of the actual spot geometry two kinds of maps were calculated from enhanced images: (I) for overview purposes a projection of the southern hemisphere to a cone and (2) for the study of details projections to a tangential pla ne for each visible spot. From these maps we determined the sizes of t he core and of the ejecta regions and their temporal changes during th e first 10 days after impact. In that way we derived wind speeds and w ind directions in the planet's stratosphere for the spots of fragments A, C, D, E, G, H, K, L, R and QI. The stratospheric winds varied from 20 to 170 km h(-1) and are thus of the order of those in the visual c loud deck. The wind directions varied strongly from region to region. We have seen material of the core region being influenced by structure s of the visual cloud deck, but a similar interrelation for the ejecta material was not evident. We neither found impact spots from the frag ments Q2, B, N (as seen by other observers) nor of F, P2, T, U, V. (C) 1997 Elsevier Science Ltd. All rights reserved.