Hello Nick

In the end I used the second set of measurements I’d obtained and by some miracle the comet appeared dead centre of my image field.  But that was the only good news. It didn’t clear my local obstructions until twilight was well advanced so all I have is a faint blob with a bright background and three brighter stars showing through.

Peter T

Sent from my iPhone

> On 7 Apr 2025, at 08:24, Fabrizio Montanucci <mc6207@mclink.it> wrote:
>
> Thank you Nick
> Based on the orbital elements you provided here, this morning I was able to image it and it was almost exactly at the predicted position.
> Based on the first set, and what is given in this other link
> https://neoexchange.lco.global/target/143872/
> I had constructed 3 data sets for the software I use (Skymap), but the first 2 gave wrong positions by several degrees.
> By tonight I should be able to send what I have acquired. There are several satellites to remove.
> best wishes
> Fabrizio
>
>> On Sun, 6 Apr 2025 12:57:27 +0100
>> Nick James <ndj@nickdjames.com> wrote:
>> 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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