Comet C/2017 O1

[Nick James]

Given that most comets are currently discovered by professional surveys when they are very faint it is most unusual that this comet has been discovered by the ASASSN team at around 15th magnitude although one visual observer has reported it as bright as mag 10. It is currently in Cetus, moving slowly northward. Details of the orbit were announced on CBET 4414. The magnitude parameters would imply that it has been brighter than 17th mag since the beginning of May but it may be in outburst. The charts attached show the path from the beginning of May through to perihelion in October when it will be tracking north through Perseus. If the current orbit is accurate it will actually pass near the north pole around Christmas.

A very nice image by Rolando Ligustri is here.

Attachments:

1. 2017o1-chart1.pdf
2. 2017o1-chart2.pdf
3. 2017o1-ephem.pdf

[Richard Miles]

Thanks Nick – Looking at its trajectory, I doubt that it is visible because of a bright outburst, rather it looks that it could have been discovered by an amateur survey in the morning sky when at a solar elongation of about 70 degrees and visible from the southern hemisphere – that would have been during the previous dark lunation, several weeks before its actual discovery by the ASASSN team.

I also see there may be some issue about the poorly chosen acronym, ASASSN, when it comes to the MPC/CBAT ascribing a discoverer’s name to this comet. No name has yet been issued. ATEL #10597 describes this object as Comet ASASSN1, which in my book is incorrect. The survey that discovered it refer to themselves as ASAS-SN so it should be Comet C/2017 O1 (ASAS-SN) – the IAU stoppeda while ago adding numbers following the name.

[Nick James]

It’s in outburst: https://twitter.com/SuperASASSN/status/889934384496640000

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