[BAA Comets] 29P has undergone a weak outburst on Dec 21 as predicted !

[Richard Miles]

Our 29P/S-W1 monitoring campaign continues apace despite the poor weather in 
some parts of the world, notably the UK.

There exists a Facebook group entitled, "PACA Outbursting Comets" and the 
other day (Dec 17.75 to be precise), I posted an alert concerning 29P 
saying: ""There's a good chance of a 29P outburst in the next few days ... 
watch that space!"

I haven't sent a 29P outburst alert for a long time mainly because the 
chances of an outburst haven't been that high recently. But on this 
occasion, the currently most active/energetic site on the nucleus had not 
outburst after its last full rotation of the nucleus (each takes 57 days) 
and so the second such full rotation of this particular location coincided 
with the last few days and that meant that the cryogeyser had a good chance 
of erupting yet again. As it happens, the outburst came within 4 days of my 
prediction. Details are:

Time of outburst: 2017 12 21.52 +/-0.40
Mag change: 16.3r' to 15.3r'
Amplitude: 1.0 mag

Here are the most recent observations showing the step change in brightness, 
courtesy of Jean-Francois Soulier and myself:
0029P KC2017 12 19.71296 21 27 20.56 -12 34 04.0 16.60N A77
0029P KC2017 12 19.74962 21 27 21.94 -12 33 57.0 16.20N A77
0029P KC2017 12 19.78733 21 27 23.28 -12 33 49.9 16.41N A77
0029P C2017 12 21.01052 21 28 08.89 -12 29 41.3 16.15N W96
0029P C2017 12 21.02079 21 28 09.27 -12 29 39.2 16.24N W96
0029P C2017 12 22.00975 21 28 46.56 -12 26 17.0 15.32N W96
0029P C2017 12 22.03291 21 28 47.45 -12 26 11.4 15.40N W96
0029P C2017 12 22.05687 21 28 48.33 -12 26 07.1 15.36N W96
0029P C2017 12 22.81198 21 29 17.05 -12 23 32.4 15.18N Z21
0029P C2017 12 22.81350 21 29 17.12 -12 23 32.1 15.31N Z21

The particular region of the comet's nucleus has one or two other, less 
active sources, one of which may also erupt in response to this current 
latest outburst, so imaging the comet during the coming days is to be 
encouraged. The comet is visible low in the south-west sky shortly after 
sunset during nautical twilight. Large apertures and a CCD camera are 
required to detect the comet. It is too faint to be seen visually through 
the telescope given its low altitude from the UK (10-15 degrees) and low 
solar elongation (50 deg).

Clear skies,
Richard Miles

P.S. If anyone would like to join the PACA Outbursting Comets group then do 
get in touch.