Hi Paul,

Thanks for the estimate, which was a bit brighter than my estimate on the same night. It is clear that the comet has faded quite rapidly as forward scattering decreased, but should now be back to the standard light curve. Last night the cloud cleared too late, but the forecast suggests it might be clear again this evening.

Just a general point, which may be of use to other contributors: to be accepted for ingest into the COBS database, magnitude observations need a source for the comparison star magnitude (I've used TJ in your case, which lists the comparison as 4.1, so comet mag 4.2), an observation method (I've assumed S, which is the BAA standard), and ideally a coma diameter (this can give some indication of observing conditions etc) and optionally a degree of condensation.

I'm slightly less fussy, though a coma diameter is definitely needed for VEM measurements and preferably one for visual estimates. As far as possible all observations go into the BAA database, whether they are complete or not, but may not be used for subsequent analysis if they are missing a coma diameter.

Regards,

Jonathan Shanklin
BAA Comet Section visual observations co-ordinator
https://www.ast.cam.ac.uk/~jds/

-----Original Message-----
From: Paul Abel - paul.abel at yahoo.co.uk (via baa-comet list) <baa-comet@simplelists.com>
Sent: Monday, October 21, 2024 11:41 PM
To: baa-comet@simplelists.com
Subject: Re: [BAA Comets] C/2023 A3 Tsuchishan-ATLAS in large telescope

Hi Nick,

Thanks for the feedback and the link to your image. I’ll continue to observe it with large telescopes for as long as possible. There was a lot of subtle detail in the core tonight and I had the image of a very active nucleus and core.

Cheers,
-Paul

--
Sent on the move.

> On 21 Oct 2024, at 23:31, Nick James <ndj@nickdjames.com> wrote:
>
> Paul,
>
> Thanks for the report and drawing and thanks, Wayne, for the image.
>
> I managed to image the comet a couple of nights ago on the 19th using my HD11 + ASI6200 keeping the exposure short so as to not saturate the central condensation. The FoV is 45 x 30 arcmin, N up. Processing the stacked image is hard since the core is so much brighter than the outer coma and tail. This image:
>
> https://nickdjames.com/Comets/2024/2023a3_20241019_181006_ndj.jpg
>
> attempts to show the full dynamic range but I am not entirely happy with it yet. It uses a mild unsharp mask and a log stretch. The insets show the a log stretch without unsharp mask and a Larsen-Sekanina filter with a rotation angle of 10 deg.
>
> There is clearly a lot going on in the central part of the coma and visual observers with large telescopes can probably pick up a lot of this. Imagers often tend to saturate the central core and thus lose this detail but modern cameras have a huge dynamic range and so are capable of capturing it if used with care.
>
> Please keep up the visual observations whenever you get a chance.
>
> Nick.
>
>> On 21/10/2024 21:58, Wayne Hawley wrote:
>> Hi Paul,
>> I was setting up for observing asteroids this evening and during my
>> setup took a few images of the comet..
>> This one is a typical image 0.36m F6.7 SDSSr' 20s 2x2, SX 694 CCD.
>> [image: 2023 A3 Tsuchinshan_20241021_190245_20s.jpg]
>> Regards,
>> Wayne Hawley Z09
>>> On Mon, 21 Oct 2024 at 21:50, Paul Abel - paul.abel at yahoo.co.uk
>>> (via baa-comet list)<baa-comet@simplelists.com>  wrote:
>>> Hi all,
>>>
>>> I had to make some tests at the University of Leicester Observatory
>>> this evening and decided to observe the comet since the cloud cleared in time.
>>> The Observatory houses a 508mm (20 inch) Planewave Dall-Kirkham and
>>> I used a power of x108 to observe the comet.  Attached is a drawing
>>> made with the
>>> telescope- there were a number of interesting points, namely that
>>> the overall colour of the comet appeared to be a distinctly
>>> golden-yellow.  The core of the comet was very bright and it seemed
>>> to be elongated and elliptical rather than a circular condensation.
>>>
>>> Alas I was unable to make any magnitude estimates as there were no
>>> sufficient field stars which could be used as a comparison.
>>>
>>> Best wishes,
>>> -Paul
>
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