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13 Vul - WDS 19535+2405 - Anyone?

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#1 R Botero

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Posted 17 August 2013 - 05:28 PM

Just before finishing last night I came across this nice tight pair. I managed to split it in moments of better seeing (wasn't so good last night - 5/10) at 200X with my 6" refractor. 4.6 / 7.4 at 1.4". Position angle confirmed versus WDS data. No colour difference.
Anyone else tried this one recently?
Cheers
Roberto

#2 mikey cee

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Posted 17 August 2013 - 11:56 PM

Just finished this double. Piece of cake with my Istar 10" F/11 R30 lens. Companion very easy to see at 815x. Seeing 8.5-9.0/10. The PA was estimated around 247°. Colors blue white and gray white for the secondary. ;) Mike

#3 R Botero

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Posted 18 August 2013 - 02:34 AM

:waytogo:

#4 fred1871

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Posted 18 August 2013 - 03:35 AM

Mikey, seems to be a very high power for a 1.4" double... I expect you were able to see the companion at less power than 815x, especially with "seeing 8.5-9.0/10". Roberto said 200x with a 6-inch "split it in moments of better seeing". Could you give a bit more detail on what it looked like at lesser powers?
Thanks.

#5 mikey cee

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Posted 18 August 2013 - 10:17 AM

Oh yes that is true. My lowest power without removing the barlow in the filter wheel nosepiece is 410x. That is the lowest power I ever use anyways with my binos. I just made it super easy to enjoy the view better. My 6" F/8 Jaegers at 212x could just make it out. ;) Mike

#6 WRAK

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Posted 18 August 2013 - 02:55 PM

Will hopefully try around mid September. Should be doable with magnification x140 and 120mm aperture.
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#7 CelestronDaddy

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Posted 18 August 2013 - 03:36 PM

Haven't tried this one. Thanks for the update...

#8 fred1871

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Posted 26 August 2013 - 08:46 PM

In another thread (16 Vul & Lambda Cyg.) Magnus has remarked on not finding this pair (13 Vul) in some sources.

13 Vul is missing from a lot of double star listings - including the Haas book, unfortunately. It doesn't appear in the older observing guides because it was not discovered until 1953. The measures since that time show a nearly linear increasing separation since that time - have a look at the orbit diagram, which plots the measures as well, in the 6th Orbit Catalog. It's in the Orbit Catalog because some brave soul has made a first attempt at calculating the orbit.

If we go backwards, before 1953, it's obvious the likely path takes the companion VERY close to the primary star - perhaps around the time when Robert Aitken, at the beginning of the 20th century, was systematically surveying the northern sky for new doubles. So it might have been missed then because it was simply too close at the time. The discovery separation was 0.8", compared to 1.4" in 2009; it could have been as close as 0.1" in the beginning of the 20th century, as suggested by the orbit diagram.

The 1953 discovery of 13 Vul as a double was due to a post-WWII double star program at Belgrade Observatory, which had a 65cm Zeiss refractor. This discovery was part of the first of a continuing series of double star studies undertaken there.

Looking at the orbit diagram, the suggestion is that this pair will soon reach maximum separation, then begin to slowly close again. We'll have to wait and see if this happens - an orbit calculated on such a modest part of a complete ellipse, and without measures yet for periastron or apoastron, is decidedly "preliminary". Likewise the orbital period of 615 years is something of a guess (it fits the calculation, but that calculation is pretty uncertain).

For now, we have another rather nice pair to observe. It'll be interesting to find out what size of scope is needed to see it split. Roberto's reported on his view with a 6-inch refractor; it might prove more difficult in a C6 or similar due to the delta-m (2.74 mags according to WDS) and the secondary star being close to the first diffraction ring, enhanced with a large CO.

Refractors? - I'm going to try it with my 140mm, I've not looked at it with that one previously. Perhaps someone would like to try claiming it with 100mm or thereabouts? ;)

#9 R Botero

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Posted 27 August 2013 - 03:43 AM

Fred
Many thanks again for the historical background. The chart on Stelle Doppie plotting observations does indeed show what a limited portion of the orbit has been recorded.
I split this one again on Sunday evening (easier than 99 Her but still close) and noticed a definite blue hue to the secondary. It also looked "fuzzy" when compared to the primary which was a much well defined disc. I remark on its "fuzziness" as after observing other (wider) doubles with a similar magnitude companions, this is one of the few where I have noticed this "structure".
Same setup as for 99 Her was used; "binoviewed" with 12.5mm orthos at 290x and 6" refractor.
Roberto

#10 magnus

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Posted 27 August 2013 - 07:10 AM

Hello Fred,

Many thanks for your very intressting data and history regarding 13 Vul. Not discovered until 1953,amazing. I was born -52 :o
I will try 13 as soon as possible.

All the best!
Magnus 57N.

#11 azure1961p

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Posted 27 August 2013 - 07:19 AM

Fred - the way you ferret out this information is really appreciated. I had no idea we were that green behind the ears on such a bright double. That it took a fellow as recent as WWII to work out the rough particulars here is surprising. Its a good thing however that such uncertainties still exist though.

Pete

#12 magnus

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Posted 27 August 2013 - 08:48 PM

Had a try on 13 this night with my orange C8 Pacific + Gemini alt-az mount. Much tougher than 16. Seeing was not quite as excellent as when I split 16 and Lambda Cyg.6-7/10 P. tonight,very humid and the corrector dewed up frequently; despite the dewcap. Had to use the "hairdryer" until I ran out of power. At 320X I saw "something" (I had not memorized the PA)almost exactly west relativ the primary, at 411X that "something" became more apparent but still I am not 100% sure of a split.Have to try this exciting binary another night!
Thanks Roberto for guiding me to this nasty devil :grin:

All the best,
Magnus 57N.

PS By the way, 16 was a clean split this night at 411X!
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#13 R Botero

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Posted 28 August 2013 - 06:52 AM

Great report Magnus. I had to pack up on Sunday evening as everything was dripping wet and could not see any stars below 8 mag! It was a shame as the seeing was very good. Best of luck on your next night out!

Roberto

#14 magnus

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Posted 28 August 2013 - 08:14 PM

Thanks Roberto!

I was out this night as well. A bit hazy and dripping wet but indeed great seeing. Stumbling near 10/10 P.
My suspected split from yesterday was defenitely confirmed with my C8 tonight at 411X and 480X. The tiny secondary was also glimsed at 320X. At close inspection the "PA" was sort of WWWS. When I use my CG-5GT mount again with tracking it will be more easy to observe this, for me, rather difficoult double.-A bit of a pain to track with alt-az slow-mow controlls above 400X!

Tonight I also had a look at zeta Hercules. Split at 411X, secondary almost due S. relativ the primary. Looked a bit like Delta Cyg. but notably tighter and the colours were yellowish.

All the best,
Magnus 57N.
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#15 R Botero

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Posted 29 August 2013 - 09:10 AM

Great split without tracking! Steady pulse! :waytogo:
Roberto

#16 magnus

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Posted 29 August 2013 - 06:31 PM

Well I have used mounts without tracking from -65 to -08. After that I have "spoiled" myself with tracking and Go-To!

Magnus 57N.

#17 R Botero

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Posted 05 September 2013 - 06:32 AM

Had fantastic seeing last night (two nights in a row - a record for SE England!) and my best split-to-date of 13 Vulpeculae. At 450x the primary's main diffraction ring was interrupted at around PA250 by a beautiful blue-green fuzzy ball. With the seeing so steady, it was great being able to dial-up the magnification so much and be rewarded with that splendid sight.

Also visited 16 Vul as per Magnus' post above. Got a nice touching pair of white discs separated momentarily by a thin black line. Diffraction rings for both components. :cool:

Roberto

#18 magnus

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Posted 05 September 2013 - 08:35 PM

Gratulations to a nice obs! I was out this night for a while and had a try on 90 Her.(first ever!)with my 6"f/12 MK66...No luck but seeing was not premium but still close, and my MAK was not 100% collimated I suspect :foreheadslap: Will take care of that when I come home from vaccation at the Croatian Riviera, Makarska.I and my wife will fly to the Croatian town Split tomorrow -Split, what a fantastic name for a binary entusiast like me :jump:

/Magnus 57N.
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#19 R Botero

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Posted 06 September 2013 - 12:56 AM

Very appropriate indeed. Enjoy Markus!

Roberto

#20 mikey cee

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Posted 01 October 2013 - 01:05 PM

I've been going back to Vul 13 and Vul 16 on a quite regular basis lately. This is to embed in my subconscious thick skull the ability to recall these same double' position's when next season rolls around. I love instant recall better than looking up coordinates. Just me. :p Mike






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