2026 July 19

C/2023 R1 (PANSTARRS) fragmentation

Nick James

On 2026 July 10 J-F Soulier reported a possible condensation in the tail of C/2023 R1 on comets-ml from images taken on July 9.91. This was confirmed in images obtained by M. Mobberley and P. Carson on July 13. An animation of Mobberley’s images is shown below. The fragment on these images (C/2023 R1-B) is around 10 arcsec behind the main component and around magnitude 18.

Subsequent examination of images in the BAA archive here:

https://britastro.org/cometobs/2023r1/thumbnails.html

showed that the condensation was visible on an image from E. Bryssinck obtained on July 8.91.

We’ve been able to get some really high-quality data from the the 2.0-m, f/5.2 R-C telescopes on Haleakala (F65) and at Siding Spring (E10) courtesy of the BAA Work Experience programme that is currently being led by Helen Usher. The images were obtained by V. Parakonna, D Benjamin, A Dragomir and A Davies. These images show a further very faint condensation around 2 arcseconds east of fragment B.

I’ve used these images to measure the drift rate of fragment B with respect to the main comet. Over four nights this is consistent with an increase in separation of 0.18 arcsec/day.

A report of these observations has appeared in ATEL #17915.

This comet is currently an evening object fairly low in the west when it gets dark. Please send any images that you obtain to the Comet Section.