Re: [BAA Comets] SWAN25F this morning.
Peter Tickner 06 Apr 2025 21:48 UTC
Now I am confused! I asked for the ephemerides for tomorrow but it started at 05:00 UT. So I asked a second time from now. It has given me from 05:00 UT again but all the values for RA and DEC are different.
Which set is right?
Regards,
Sent from my iPhone
> On 6 Apr 2025, at 13:03, Peter Tickner - peter.tickner1472 at btinternet.com <baa-comet@simplelists.com> wrote:
>
> Thanks Nick
>
> That looks more promising provided the weather holds. I’ve just upgraded my mount from an EQ8 to a Mesu E200 Mk 2 so I’m still getting the hang of using the mount software at the moment - that didn’t help this morning.
>
> Peter T
>
>
> Sent from my iPhone
>
>> On 6 Apr 2025, at 12:57, 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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