At www.physorg.com/print252331686.html … computer simulation of the July of 2009 impact event, picked up by an amateur astronomer the following day, has tried to find out what size and composition of object it would have taken to achieve what was observed the day after it happened. The amateur alerted mainstream astronomers and telescopes were turned to fix on Jupiter – so quite a bit of evidence was in fact accumulated. Disturbance in the atmosphere of Jupiter was observed (see image) and in addition, ammonia transport from the upper troposphere to the stratosphere by means of impact plumes – which is still subject to investigation. That is an interesting point as Mike Baillie has suggested ammonium spikes on Earth are a proxy signature for impact events – for example in 1014AD. Likewise, the Tunguska event did not cause narrow growth tree rings but it did come with an ammonium spike.