I've just imaged 12P in the bright twilight. Comphot gives a magnitude
of 9.3 in a 90 arcsec aperture on Nov 15.721. The inner bright coma is
now around 34 arcsec in diameter and I get 9.4 in that aperture. Both of
these measured in a single 60s unfiltered frame.

This is a really big outburst!

Nick.

On 15/11/2023 09:51, Peter Carson wrote:
> Hi Nick,
>
> I confirm the outburst of 12P. I’m seeing a 5 magnitude increase in 24 hours!
>
> My images on Nov 13.86 give mag 15.0 Gaia G in an 11 arcsec dia aperture.
>
> My images from last night  Nov 14.85 give mag 10.0 Gaia G in an 11 arc sec dia
> aperture.
>
> Looks like another major outburst is in progress.
>
> Peter
>
> Peter Carson
>
> Leigh on Essex
>
> Remote observatory in Extremadura, Spain.
>
> Sent from Mail <https://go.microsoft.com/fwli nk/?LinkId=550986> for Windows
>
> *From: *Nick James <mailto:ndj@nickdjames.com>
> *Sent: *15 November 2023 06:52
> *To: *baa-comet@simplelists.com <mailto:baa-comet@simplelists.com>
> *Subject: *[BAA Comets] Possible 12P outburst on or before Nov 14.75
>
> Morning all,
>
> I've just measured my 12P images from last night using Astrometrica and
>
> it is around 2 magnitudes brighter than three days ago measured in a 9
>
> arcsec aperture.
>
> On Nov 11.77 using this aperture I had mag 14.5. Last night in 20
>
> minutes around Nov 14.75 the comet rose from 13.6 to 12.5.
>
> Can anyone confirm?
>
> Nick.
>
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