C/2017 K2 (PANSTARRS)

After yesterday’s meeting at Burlington House Peter Carson has obtained some more astrometry of this object. I’ve added that to the collection and the output from findorb is attached. As I said at the meeting yesterday the period and perihelion date are very poorly constrained at the moment and the residuals aren’t much different if you force the orbit to be parabolic. Astrometry over the next couple of weeks should start to resolve that so we should at least have a good idea of the orbit. It will be a few years before we can even guess how bright it is likely to be when it comes to perihelion in 2023.

The orbit is still very uncertain but all the astrometry to date (a 25 day arc) implies that it is near parabolic with a perihelion at 1.8au at the end of 2022 or early 2023. This is much less interesting than if it had been in a shorter period orbit since it probably means the that the comet is dynamically new. Such comets tend to have significant activity far from the Sun but then the underperform as they move into the inner Solar System. Still, it is worth observing this comet if you have the equipment. It is very well placed and you don’t often get the chance to image comets which are 16au away.