[BAA Comets] Comet 29P/SW1 and HST "Comet Outburst Target of Opportunity"

[Richard Miles]

Following note has been issued on the new Groups.Io service:
(Yahoo members are encouraged to migrate to the new facility)
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This note is to alert observers that, starting on 2019 October 14 and 
finishing on October 29, the Hubble Space Telescope will be making 3 visits 
to observe 29P: the latest news is that the first planned HST observations 
have been successful! The investigation, which aims to go deep in 3 colors, 
and if possible to catch 29P shortly following one of its outbursts, is led 
by Dennis Bodewits of Auburn University along with his co-investigators; 
M.S. Kelley, J.-Y.Li, E. Jehin, S. Protopapa and Q. Ye. It is the first time 
since 1996 that Hubble has been used to observe 29P.

The proposal for Observing Program 15965 can be found at:
http://www.stsci.edu/hst/phase2-public/15965.pro

It is therefore important that ground-based observers keep a close watch of 
29P's activity during the course of this ToO campaign so that we can 
establish the comet's outburst history in detail, especially during the HST 
observing window. 29P is readily observable as an evening object these next 
few weeks, with the Moon now waning and moving well away from the comet. 
Imaging either unfiltered or with a red filter is recommended.

N.B. During the past 100 days, the comet has undergone NINE well-observed 
outbursts, but for most of this time the comet has remained faint at an R 
mag ~16 because EIGHT of these have been low-intensity events with 
amplitudes of only 0.28-0.60 mag. Up until recent years, such 
'mini-outbursts' went undetected. The last two mini-outbursts took place on 
October 7 (0.50 mag) and October 16 (0.30 mag). We were fortunate to obtain 
high cadence observations before and during the October 7 event, thanks 
largely to Jean-François Soulier (L27), Ramon Naves (213), Mario Morales 
(K14), Denis Buczynski (I81) and Las Cumbres Observatory (K91, W87). This is 
the first time that an outburst has been followed from quiescence through to 
maximum light - an exciting new advance in the study of this most bizarre of 
periodic comets.

I should add that, as one of the activities of the Comet Section of the 
British Astronomical Association (BAA), I oversee a 29P Photometry Campaign, 
and so feel free to correspond with me if you are not yet involved and wish 
to be. Some advice on the photometry side of the campaign is at:
https://britastro.org/node/18562

There is also a (largely) professional astronomer's 29P Observing Campaign 
initiated by Maria Womack of the Univ. of Maryland. See:
http://wirtanen.astro.umd.edu/29P/29P_obs.shtml

I look forward to hearing from you.
Richard Miles