Peter,

Select SWAN25F on the PCCP here:

https://www.minorplanetcenter.net/iau/NEO/pccp_tabular.html

and you can generate an ephemeris for your location. It will be very
accurate since the astrometric arc is now over 6 months.

The latest elements using all of the astrometry on the PCCP are:

    Perihelion 2025 May 1.15811 +/- 0.000324 TT =  3:47:41 (JD
2460796.65811)
Epoch 2025 Apr  6.0 TT = JDT 2460771.5   Earth MOID: 0.6280   Ju: 0.4022
M 359.99997631 +/- 0.0000030        Me: 0.0057   Sa: 0.5696      Auto-Find
n   0.00000094 +/- 1.23e-7          Peri.  153.85086 +/- 0.00022
a  10309.2556 +/- 910               Node   329.84397 +/- 0.00006
e   0.9999676 +/- 2.83e-6           Incl.   90.37330 +/- 0.00036
P1046745  H   11.31    G   0.15     U  2.1
q 0.33341258 +/- 1.53e-6    Q 20618.1778 +/- 1902         (J2000 ecliptic)
159 of 167 observations 2024 Sept. 3-2025 Apr. 6; mean residual 0".45

It is looking as if the comet is dynamically old (although with a very
long period) so that is encouraging.

Nick.

On 06/04/2025 12:48, Peter Tickner - peter.tickner1472 at btinternet.com
(via baa-comet list) wrote:
> Hello Nick
>
> I looked and failed on those listed coordinates this morning. Partly I think because it didn’t clear local obstructions until civil twilight had started and partly looking through my f/10 14inch SCT there wasn’t much room for error.
>
> Are there any updated coordinates?
>
> Regards,
>
> Peter
>
> Sent from my iPhone
>
>> On 6 Apr 2025, at 12:44, Nick James <ndj@nickdjames.com> wrote:
>>
>> I imaged the comet from Chelmsford again this morning and it was considerably brighter than yesterday. I get the following total magnitudes and coma diameters with comphot using a 51mm, f/4.9 refr. + ASI2600MC. Green channel vs Gaia G DR3:
>>
>> 2025 April 5.157    9.6    2.3'
>> 2025 April 6.150    8.0    3.8'
>>
>> Transparency was probably a bit better this morning but conditions and time were similar.
>>
>> Interesting behaviour so please observe this comet if you can and submit magnitude estimates. It is still on the PCCP so no official designation yet.
>>
>> Nick James
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