This is quite outstanding, Nick.
Congratulations on discovering this dramatic event just minutes after it
started enabling the rest of us to follow up too.

This is only the second bright outburst this apparition, i.e. since May this
year.
Of all the other events, of which there have been 13, the brightest only
reached 15.5R: this is because those events are caused by a different
population of vents on the nucleus - I call them cryogeysers.

Here's what we have for the two bright events this year:
2020 Jul 26.89   17.0R => 12.9R
2020 Nov 19.77   16.2R => 13.2R
Time difference = 115.88 +/-0.13 days = 2 x 57.9 days

My solution for the periodicity of activity on 29P is 57.7 days (published
in Icarus in 2016 based on data to 2014).
That's astounding that the same cryovolcano has erupted, almost exactly two
rotations of the nucleus apart.

There's even more remarkable 'coincidences'.
The strongest outburst of the 2019-20 apparition was on:
2020 Feb 02.41   17.15R => 13.35R
Time difference = 175.48 +/-0.20 days = 3 x 58.5 days
So this cryovolcano has been going off multiple times.

One last coincidence:
Today's eruption was preceded by a 0.24-mag mini-outburst that occurred
3.7+/-0.1 days earlier.
That of 2020 Jul 26.9 was preceded by a 0.28-mag mini-outburst  that
occurred 4.1+/-0.2 days earlier.
That of 2020 Feb 02.4 was preceded by a 0.40-mag mini-outburst  that
occurred 7.0+/-0.4 days earlier.

This comet nucleus is totally amazing!
Richard

----- Original Message -----
From: "Nick James" <ndj@nickdjames.com>
To: <baa-comet@simplelists.com>
Sent: Thursday, November 19, 2020 9:15 PM
Subject: Re: [BAA Comets] Observations of 29P

> Here's my lightcurve so far tonight. The gaps are where I've been off
> doing NEO astrometry but it looks as if it is beginning to flatten out
> around 13.3 or so. Denis Buczynski had is at 16.2 at JD 2459173.25314 so
> it has risen 3 magnitudes in 3 hours.
>
> Nick.
>
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