[BAA Comets] 2019 Observing Campaign on Comet 29P/Schwassmann-Wachmann

[Richard Miles]

Amateur astronomers keep a close watch on comets and by far the most 
observations in the Minor Planet Center (MPC) database are for Comet 
29P/Schwassmann-Wachmann 1. The reason is that this object is in a 
near-circular orbit just beyond Jupiter and so is observable for about 80% 
of the time on average, but more especially because it exhibits recurrent 
outbursts, the nature of which have yet to be explained. Amateurs are 
ideally placed to monitor its activity.

Since 2014, I have been overseeing a photometric observing campaign, the aim 
of which is to obtain frequent, accurate nuclear (m2) magnitudes. 
Observations during the 2016, 2017 and 2018 apparitions have detected totals 
of 17, 20 and 18 outbursts respectively, about 50% of which were in excess 
of 1.0 mag amplitude. The 2019 campaign is now well underway: 29P as a 
morning object having reached quadrature yesterday (2019 July 12). Evening 
quadrature arrives 2020 January 3 and so 29P will be readily observable for 
the rest of 2019 at a declination of +13 to +16 degrees in the 
constellation, Pisces.

Many amateurs have already contributed to the campaign but if you have yet 
to do so and are interested then you will need a fairly large telescope, say 
at least 15-cm aperture (the larger the better!) and a focal length of >100 
cm, as well as an image scale for your camera of preferably <2.0 "/pixel. 
Use a monochrome camera, and take a series of exposures using either no 
filter, a Luminance filter, or Cousins or Sloan red filter. A tutorial on 
how to undertake and analyse your images is on the BAA website at:
https://britastro.org/node/18562

Note that the analytical approach is different to astrometric measurement of 
images, being expressed to two decimal places precision in magnitude. Do let 
me know offline if you are new to this and are planning to take part in the 
2019 campaign. Note that you can also report your astrometric/photometric 
measurements to the MPC but to do so you will need to round down your 
photometry to the nearest 0.1 magnitude. Photometric results should be sent 
to me offline. The occasional progress report and individual feedback will 
be sent to all active participants. Any questions and I'll be glad to help.

Thanks in advance,
Richard Miles
British Astronomical Association