[BAA Comets] C/2017 S3 PanSTARRS

[Nick James]

C/2017 S3 PanSTARRS continues to brighten and it doesn't show any sign 
of imminent disruption so this does have the potential to become a 
fairly bright object over the next few weeks as it heads towards 
perihelion (q=0.21) on August 15. The current COBS lightcurve is here:

https://cobs.si/analysis2?plot_type=0&end_date=2018/09/30%2000:00&col=comet_id&fit_curve=1&perihelion=1&obs_type=3&id=1690&start_date=2017/09/01%2000:00

The brightening does appear to have been sustained although you should 
take the predicted magnitude fit with a large grain of salt since this 
is a dynamically new comet and we don't really know what it will do as 
it approaches the Sun.

It is really important to keep this object under observation for as long 
as possible. The observing circumstances are getting more difficult as 
the elongation reduces so you will need a good northeastern horizon but 
if it does get bright binoculars or a portable imaging setup should be 
sufficient to get good data.

Observing circumstances after perihelion are poor but Worachate Boonplod 
has pointed out that it should be in the SOHO C3 FoV from August 14. It 
should also be visible in the STEREO HI1-A FoV from July 31.

Nick James, Director.

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