Fragmentation of comet C/2025 K1 (ATLAS)

[Nick James]

This comet was reported to have fragmented on or about November 4 (ATEL 17482, 17487, 17488). There are several fragments but the two brightest are the main component and fragment B. Recent images are in the archive here:

https://britastro.org/cometobs/2025k1/thumbnails.html

Attached is a plot of the all the astrometry that I have. The recent astrometry consists of my measures using the Alnitak telescope in Spain (I79) on Nov 12 and 13 and Denis Buczynski’s measures using his telescope in Tarbatness (I81) on Nov 14. The plot shows the residuals for the main component as filled circles and the residuals for component B as open triangles. These residuals are from the fitted orbit using all the available astrometry (from the MPC) prior to November 4.

The main component shows a large positive RA residual which is matched by a similarly large negative residual for fragment B. A simple-minded interpretation of this would be that both components have a similar mass but fragment B is much fainter so that doesn’t seem likely.

If anyone has any recent (post November 11) astrometry of this comet please forward it to me and the MPC. Astrometry of the main fragment (C/2025 K1-B) would also be very useful. It is now well separated from the main component.

• This topic was modified 16 hours, 47 minutes ago by Nick James.

Attachments:

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   2025k1_20251113_051956_ndj.png
   

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   2025k1_residuals.png
   

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