Observation by Nick James: 12P/Pons-Brooks in outburst

Uploaded by

Nick James

Observer

Nick James

Observed

2023 Jul 23 - 21:49

Uploaded

2023 Jul 23 - 22:27

Objects

12P Pons-Brooks

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Constellation

Draco

Field centre

RA: 18^h13^m
Dec: +55°49'
Position angle: +3°05'

Field size

0°14' × 0°10'

Equipment

ASI6200MM + Celestron HD11

Exposure

14x60s

Location

Chelmsford, UK

Target name

12P/Pons-Brooks

Title

12P/Pons-Brooks in outburst

About this image

I had sub 2 arcsec seeing tonight just as it got dark. The coma is now 40 arcsec in diameter and this is definitely one of the oddest shaped comets that I have seen.

Files associated with this observation

12p_20230723_214920_ndj.jpg (437.3 kB)

Like this image

Mazin Younis, David Strange, Mike Harlow, Peter Carson

Comments

Mazin Younis, 2023 Jul 24 - 01:34 UTC

Great pic Nick, how would you explain this peculiar shape of the coma?

Nick James, 2023 Jul 24 - 05:24 UTC

Richard Miles has suggested an explanation on comets-ml here. We see a similar effect in 29P outbursts although it is not as pronounced. The outburst happens over a very short time period and the material rises above the nucleus and then expands spherically into a vacuum. One direction is blocked by the nucleus itself, hence the dark lane. In that post Richard also suggested that the particularly exaggerated shape might be caused by a bi-lobate nucleus. I'm not convinced by this but it is an interesting idea! This is definitely a comet worth keeping under observation as it comes in to perihelion next year. We have an opportunity to observe it in a lot more detail than the last time it came to perihelion in 1954.

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