DISINTEGRATION OF FRAGMENTS Q1 AND Q2 OF COMET SHOEMAKER-LEVY-9 DURING THE FALL TO JUPITER

The largest and brightest fragment Q of Comet Shoemaker-Levy 9 broke u p into pieces, Q1 and Q2, well before the collision with Jupiter. The bleak up continued as the comet approached Jupiter and entered its atm osphere. This is confirmed by an analysis of a few series of photometr ic observations of an optical echo from Jupiter's satellite Io obtaine d on July 20, 1994 during the fall of Q1 and Q2. The optical echo from 10 was recorded seven times before the observations from the GALILEO spacecraft. No fewer than eight explosions of the pieces of fragment Q were detected. Their difference in size resulted in different power a nd duration of the observed effects. A discussion of the visibility co nditions for the explosion sites from Io and from the GALILEO spacecra ft show that since their zenith distances (53 degrees and 70 degrees, respectively) differed markedly, the sizes of the optically transparen t regions formed above the explosion sites could be large enough to di rectly view a fireball from lo and too small to observe it from GALILE O.