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Close-up Detail of 46P/Wirtanen.

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#1 David Gray

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Posted 11 December 2018 - 09:46 AM

Still fairly low here but saw it well naked eye: possibly 4.8- 5.0, but more crudely from simple comparison viewpoint I might describe it thus……….

 

This was a particularly good sky and as M33 was well enough visible with direct vision (high overhead) I rather felt that the comet was around 2/5 & 3/5 in brightness twixt that of M33 & M31.  Not that I would submit such a judgement as a formal estimate, but just to convey the impression.

 

As I say a very good sky (very clear overhead) with a scattering of a few faint stars northward of M33 suggesting I was seeing to 6.8 – maybe 7.0 (av) – a 5.8 star close east of them being very easy and a 6.3 star well seen with direct vision (dv).

 

A striking sight in the 20x100s but the view with the D-K showing well the cool-green glow almost filling the field; also a fair bit structure apparent decided me to sketch that scene. 

 

Spent a tiring day yesterday trying to get a good ‘scan’ of this sketch and again this morning: camera fault……….but seems to have fixed itself – after a good cussing……….!!!

 

Those tail-filament features were only surely seen by av and sweeping across/in RA, so not claiming accurate placement; but a couple of more northerly ‘clumps’ were well seen directly – getting me looking for more…….

 

Caught it again last night during a brief clearing but not as clear as the 9th; even so did not need much dark adaption to pick it out naked eye.  When adapted it was very easy and it took av to pick out 6.0 stars in the region, and about 6.3 in that higher Triangulum field; M33 being uncertain with dv.

 

Dave.

46P Wirtp2.jpg


Edited by David Gray, 11 December 2018 - 09:53 AM.

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#2 Tom Axelsen

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Posted 11 December 2018 - 10:34 AM

Wow! Beautiful drawing and amazing details. bow.gif



#3 kkennardis

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Posted 11 December 2018 - 12:58 PM

Great shot



#4 niteskystargazer

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Posted 11 December 2018 - 02:56 PM

Dave,

 

Very nice Close-up Detail of 46P/Wirtanen smile.gif .

 

CS,KLU,

 

thanx.gif ,

 

Tom



#5 Jef De Wit

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Posted 11 December 2018 - 05:59 PM

You catched a lot of detail waytogo.gif 



#6 acr_astro

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Posted 12 December 2018 - 04:17 AM

What a wonderful drawing! Thanks for sharing with us here!

 

Achim



#7 Susan H

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Posted 12 December 2018 - 05:22 AM

Wow, David. That’s incredible! Such detail. Nicely done. Thank you for sharing. If I can get a clear night, I’d like to try my hand at sketching this comet as well. But, I don’t believe I can top this sketch...well done, David. Clear skies. 



#8 arnaud_dupuis

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Posted 12 December 2018 - 06:09 AM

Oh wow! Amazing view and sketch. Thanks for sharing!

Sent from my Pixel 3 XL using Tapatalk

#9 Heidescoper

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Posted 12 December 2018 - 07:08 AM

hi all,

David:
what a beautiful, detailed sketch.
I saw a night later again jets with my 12" Dobson.

CS
Christian

#10 David Gray

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Posted 12 December 2018 - 07:06 PM

Many Thanks All for the good words and the Likes……..smile.gif

 

Great conditions again tonight, but by I got the comet the seeing was too poor to get certainty with some finer tail and coma structure – there I’m pretty sure, but not amenable with accurate sketching.

 

Those great conditions had endured as that ribbon of the jetstream passed over; and now the seeing breaks down…...  No simple relationship twixt jetstream and seeing I have been persuaded of for some time now……crazy.gif

 

Dave (Off to bed!).



#11 frank5817

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Posted 12 December 2018 - 11:22 PM

David,

 

Fantastic sketch full of fine detail.

 

Frank :)



#12 Aquarellia

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Posted 13 December 2018 - 12:38 AM

Pfiouuuu bravo David!  This is exactly the view I had some nights before but with more details with your top scope and eye view. I sketched this core too when making a sort of exercise to detect the paralax of this comet between France and Quebec.

Michel


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#13 astronz59

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Posted 13 December 2018 - 01:32 AM

Now that's an impressive sketch! bow.gif waytogo.gif



#14 astronz59

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Posted 13 December 2018 - 01:51 AM

Would your estimate therefore be (M33)2 vs (M31) 3? If so your estimate would equate to 5.72 - 3.44 = 2.28.

 

2/5 of 2.28 = 0.91, so Est. Mag = 5.72 - 0.91  = 4.8.

 

What do you think?  smile.gif


Edited by astronz59, 13 December 2018 - 01:51 AM.

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#15 Aquarellia

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Posted 13 December 2018 - 09:39 AM

Sorry to disturb your nice post David but I add here my observation with my little DK, just as a comparison:

 

46p-20181210-pn_l.jpg

 

NB: I heard somewhere that rotation of the nucleus is +/- 6 to 8 hours.


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#16 David Gray

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Posted 13 December 2018 - 11:36 AM

Many Thanks Frank, Astronz, Michel….

 

Would your estimate therefore be (M33)2 vs (M31) 3? If so your estimate would equate to 5.72 - 3.44 = 2.28.

 

2/5 of 2.28 = 0.91, so Est. Mag = 5.72 - 0.91  = 4.8.

 

What do you think?  smile.gif

Thanks for that Astronz…….being an ‘impressionistic’ comparison I had not thought to reduce it to actual magnitudes, but it lines up nicely with the actual rough estimate I had made earlier that night….”...possibly 4.8-5.0.....”

 

Now getting higher here; last night I thought it possibly brighter than 4.5 – near 4.0 even!

 

Dave.



#17 Daniel

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Posted 13 December 2018 - 11:41 AM

I'm curious. Has anyone noticed more than one object around the comet core? I took a series of 2 hours of 300 second guided shots the other night. With my raw shots...I was processing some to look at the core up close. It appeared to me to be 2 small artifacts besides the main core. They were holding position as I looked at other photos. Has anyone else seen this or am I the only one?



#18 Heidescoper

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Posted 13 December 2018 - 02:13 PM

hi all,

sorry too...

Michel:
very interesting !
I made a sketch few hours later.
Here my original sketch - quick and dirty -

11.12.2018, 00:10 UT
12" Dobson, V 167x

I couldn`t finish the observation because there came clouds, but we saw the same three jets !!!


CS
Christian

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#19 astronz59

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Posted 13 December 2018 - 03:50 PM

Michel and Christian -outstanding observations gentlemen! waytogo.gif



#20 Randolph Jay

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Posted 13 December 2018 - 06:57 PM

Fantastic sketch!

Regards,

Randolph



#21 azure1961p

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Posted 14 December 2018 - 06:52 AM

Now that's brilliant Dave. Those gossamer tendrils just beginning to emerge from the Halo... honest... This is an exquisite piece. Rain all this weekend for me so... Yeah ... no Wirtanen!!

 

Your piece makes a great argument for looking. So glad you bored into the coma for this revealing piece.

 

Pete



#22 stanislas-jean

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Posted 14 December 2018 - 07:01 AM

Hi David,

Not a great sketch but rather an exceptionnal report from you, so detailed.

For the brightness evaluation, it may be compared those from the accessible messiers, in capella (the comet is brighter), in andromeda (the comet looked similar to M31). I had a look yesterday evening with a simple binocular 10x42ED sothat the comments came from.

Both the comet and M31 were accessible to the naked eyes here, 30kms from Paris, with a 6/6 transparency sky.

Will try again this evening if possible with sky transparency and greater aperture.

Good skies.

Stanislas-Jean



#23 Warmvet

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Posted 14 December 2018 - 01:50 PM

Great details and such fine portrayal of the comet including the colors recorded. Like looking through an eyepiece. I observed the comet last night as well but could not see the tail filament features due to average poor seeing. I will keep trying as they are fascinating.

 

Michel, If the nucleus is rotating (I also remember reading this) would the filament features change in accordance? Ie not always 3 filaments?

 

Enjoyed seeing your sketchs as well Michel and Christian

 

Cindy



#24 Aquarellia

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Posted 15 December 2018 - 03:45 AM

Great details and such fine portrayal of the comet including the colors recorded. Like looking through an eyepiece. I observed the comet last night as well but could not see the tail filament features due to average poor seeing. I will keep trying as they are fascinating.

 

Michel, If the nucleus is rotating (I also remember reading this) would the filament features change in accordance? Ie not always 3 filaments?

 

Enjoyed seeing your sketchs as well Michel and Christian

 

Cindy

Hi Cindy

 

Indeed the nucleus is rotating.

I feel also that the longer jet is stable, maybe not rotating (?), but this is very difficult to be sure, it looks as the jet is the one opposit to the sun, as a ion tail start.

But nobody understand already how it is rotating, we receive scientific info from 6h to 9h per rotation.  And that seemed not comming from the center of the nucleus, as a Mascon effect (for Mass Concentration as the ones on the moon - nothing to see with Macron lol.gif ).

From the position of the jets represented on my two first sketches and because of the confirmation from Christian, I made a rappid calculation, mathematicaly I got two solutions: 6.1h and 8.7h.

As you can read further Farnham et al. (CBET 4571) report a rotation period of 8.91 hr, not too bad isn't it?

 

You can read more info about that in this good site : http://wirtanen.astr...6P_status.shtml

 

About the number of filament the gif picture you can see in this site gives a good idea.  Yesterday night I made 3 sketches, 235x, 375x with and without SWAN filter, in one of those images I show a sort of circular jet but not on the 2 other ones.

We are reach really the limit of the eye perception here.

Michel


Edited by Aquarellia, 15 December 2018 - 03:46 AM.

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#25 David Gray

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Posted 15 December 2018 - 10:33 AM

Many Thanks To All again…….

 

A very poor grey sky last night but the comet soon picked up in the 12x65s – suggesting it now more impressive than before in better skies.

 

Not sure if this is the gif Michel alludes to with those filaments……..

 

http://www.britastro...13_grhemann.gif  Edit: Seems this goes to the Home Page but clicking on the Comet Section page then Image Archive then 46P and scroll to bottom.

 

They are very elusive visually – perhaps overstated in my sketch – as they were only seen (av) as depicted by sweeping back and forth in RA.  In fact I felt there was a lot of complexity beyond  true-rendering – almost a helix-like – ‘corkscrew’ – effect!

 

Dave.


Edited by David Gray, 16 December 2018 - 08:16 AM.



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