Comet 29P/Schwassmann−Wachmann: Three outbursts now successfully predicted

2014 May 24

Richard Miles

This is a follow-up to my article published in the 2013 August issue of the Journal (Vol.123(4), 229-230) on the subject of this enigmatic comet, in which I reported my successful prediction of an outburst which took place on 2013 June 12.
Since Comet 29P outbursts every few months, the odds against correctly predicting the outburst date (plus or minus a few days) are about 1 in 10, so the chosen date may easily have coincided by chance with an outburst. Since that time, two further energetic outbursts of the comet have been observed; one on 2014 Mar 02, and another very recently on 2014 May 01. I am on record via the comets-ml webgroup as having now forecast both of these latest events (see Table 1).
Assuming that the predictions are independent the probability that all three of my predictions have been correct by sheer chance is around (1 in 10)³, i.e. about 1,000 to 1 against. Clearly the model underlying the predictions, which is based on the comet’s last 12 years’ activity, provides a fairly accurate description and is to some degree able to foretell its future behaviour.
The comet is renowned for its frequent outbursts and amateur astronomers make a very valuable contribution by regularly monitoring it. The >16,300 photometric observations since 2002 reported to the Minor Planet Center (MPC), largely by amateur observers using small telescopes, have been of crucial importance in elucidating the nature of this comet. An analysis of these and other Faulkes Telescope observations made by schools, colleges and amateur astronomers is given in a paper by myself and eight co-authors, submitted in early April to Monthly Notices of the Royal Astronomical Society (MNRAS).
To my knowledge no-one has ever successfully forecast an outburst of a comet. Heating of comet nuclei reaches a maximum near perihelion and so comets tend to outburst at or around that time. So what is the story behind these successful predictions of 29P’s outbursts, which arose some 5-6 years prior to perihelion passage?

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