Delta Cygni and a few more .....

[John]

My 6" F/8 refactor is turning out to be a really good binary scope now that the scope is properly collimated and Chromacor is giving closer to it's best

As well as finding my old favorites Porrima (Gamma Virginis) and Izar (Epsilon Bootes) I got a good clean split on Delta Cygni this evening at 240x. I believe the separation here is 2.5" but with the big brightness difference between the componants (mag 2.9 and mag 6.3 respectively I believe) it's another challenging binary that I'm pleased to have split

I'm going to have a binary summer I think

Is there an online reference to current magnitudes / position angles / separation of binaries or should I invest in the BAA Handbook ?.

STOP PRESS:

I've just managed to achieve a split of Zeta Herculis !!!!

It's a really, really tight and challenging unequal pair - I think the separation is just 1.4 arc secs. The dimmer of the pair (mag 5.5) appeared as a brighter spot in the 1st diffraction ring of the brighter (mag 2.9) star at 240x. The dimmer star was more of a "bump" on the side of the airey disk of the brighter one at this power with only a questionable split. I upped the power to 343x and was starting to see the hairline of dark space between the two intermittantly - but it was there. As the seeing was favourable I upped the stakes again with a 3x barlow / 7mm Nagler to get 514x (!) but the image held and I was able to get clear airey disks with the slimmest sliver of dark between them. I reckon that's my limit with this scope on this night or perhaps any night. Very challenging by very satisfying as well

I only hope that someone is not going to say that the separation is sub-arc second at the moment and I've been fooling myself

[lunator]

John

Good splits

I will check on zeta Herc but I beleive it is about 1.4" at the mo.

I can recommend the Cambridge Double star atlas CDSA. mine has been fully used and abused

Sisy Haas' book is good but it a list.

On the web there is the Spirit of 33 and also PJ Anway's website has a good list. I will track down the URL.

Cheers

Ian

[DarkerSky]

John - I had a go at Zeta Herc Friday night with my 16" LB. Seeing was poor. I had a hint of a split a couple of times at x377 magnification, but really couldn't be sure that I'd got it. The image was too jumpy. If there was anything there the PA I would estimate was roughly North - maybe around 350 degrees.

What PA did you get?

[mdstuart]

Love the report

I have split Izar with my 10 inch, I used to struggle with the smaller scopes.

Might try delta cygni tonight then..

I will leave that Hercules one to those with high F numbers.

Mark

[John]

John - I had a go at Zeta Herc Friday night with my 16" LB. Seeing was poor. I had a hint of a split a couple of times at x377 magnification, but really couldn't be sure that I'd got it. The image was too jumpy. If there was anything there the PA I would estimate was roughly North - maybe around 350 degrees.

What PA did you get?

Thanks for having a look. I'll see if I can have another go tonight but my backs playing up and there are quite a lot of clouds about.

I'll try and sketch what I see this time as well

My view is through a mirror diagonal so N/S will be reversed from your view but E/W will be the same (I think ?). I'll try and take that into account in the sketch.

[John]

Well here is my (rather poor) attempt at drawing Zeta Hercules as seen with my 6" F/8 refractor + Chromacor at 300x (4mm ortho) and 343x (3.5mm Nagler). The images are obviously much enlarged in the sketch. The star colours that I discerned were yellow/white for the brighter componant and pale brown / orange for the fainter one. I used the ortho to check the colours in case the Nagler was intoducing any tint.

This is very much an "on the margin" split with the dimmer star apearing as a brighter and more condensed spot in the, somewhat broken, diffraction ring created by the brighter star. This sketch was drawn as I saw it with a mirror diagonal, N at the top, W to the left however I have flipped it vertically so that the view below should match the newtonian view that DarkerSky had. My estimate of the PA would be around 320-340 degrees but thats only an estimate:

[lunator]

JOhn

That is a pretty good close up sketch

The view is usually that 'wobbly'

Cheers

Ian

[John]

Thanks Ian,

From research I've done on the web my colour asessment is about right. The period of the pair is just 34.5 years so the PA changes rapidly and the separation can vary between .6" and 1.34" - I reckon it's about 1.1"-1.2" at the moment so, given the uneven brightness of the componants, its a very tough challenge with a 6" (or even a 16" !).

[lunator]

Hi John

I hope to have a go at this with the 10" very soon.

It will need decent seeing

Cheers

Ian

[John]

Hi John

I hope to have a go at this with the 10" very soon.

It will need decent seeing

Cheers

Ian

I look forward to hearing about that Ian

[DarkerSky]

Super sketch and observation John. My PA was only a rough estimate, so we do seem to be concurring in the same general direction, which is great. Certainly gives me more confidence that I might have made the split. Will definately give it another go when the sky clears. It certainly is a tough one !

[Mark at Beaufort]

Hello John

Interesting report and I really must undertake more double star observing especially with my 4" APO frac. I enjoyed Ian's (Lunator) talk at SGL5 and I have since bought the Cambridge Double Star atlas (very detailed).

John you have given me some useful doubles to start with especially as they are currently well placed.

Regards

Mark

[F15Rules]

Hi John

Fascinating report and I think your sketch is very good:)!

I have always struggled with Delta Cygni and am sort of relieved at reading your report..at 2.4" it should be well within the reach of a 4" refractor -or even a 3"..but I have never been able to split it with either size of frac, so was starting to think it was my eyes, especially since my older textbooks seem to expect it to be relatively "doable" with these size scopes..

At long last I am due to receive my new 6" F12 in the next week to 10 days, so I am really looking forward to trying it on some of the stars you refer to in your report..will keep you posted and thanks again for the interesting stuff:headbang:

cheers

Dave

[Moonshane]

Interestingly I managed to split Delta Cygni recently for the first time I can recall.. see http://stargazerslounge.com/observing-discussion/144803-double-stars-dont-afraid-use-ludicrous-magnification.html and it's good to see John used high magnifications as I did. I will try Zeta Herculis too and see what I can get with the high mags. It's pretty high currently so will hopefully be doable.

I was delighted and surprised that you can use such high power on double stars and retain relative sharpness. It's almost the exact opposite of planetary observing where more power helps less and less in terms of details.

[John]

Good luck with Zeta Herc Shane - subsequent observations I've made have lead me to doubt my original observation

[lunator]

John

What is causing you to doubt?

[John]

John

What is causing you to doubt?

The fact that I've not been able to repeat the observation that led to my drawing - even with scopes that are optically better performers, under good conditions.

I'm going to give it another try though - my 6" mak-newtonian is my best binary scope currently - very sharp and well defined star images

[Moonshane]

oooh, interesting John. I'll report back when I have a butcher's.

[F15Rules]

Hi John,

I managed a very clear split of Delta Cygni last Saturday night...I was golng/am going to include it in my first light report (Evo 6" F8, same optics as yours last year but minus Chromacor:mad:..

I was absolutely delighted. I have tried so hard with this famous double in the past, I even doubted I had the right star! Even with my 5" Tal I never got a split I could honestly say was definite..sometimes I think I've seen what I want to see:eek:..

But Saturday night the transparency here was superb and seeing was very good...for example, I could see all the main stars around Antares very easily with the naked eye, and that's always difficult with their low elevation in the UK. I also found a nice (small) globular near Antares, can't remember what number it was, but it was very clear, just small, and grainy at the edges, yet so low down.

Delta was very cleanly split at around x320 (barlowed Ultima 7.5mm) and I have absolutely no doubt about it!

The other thing I've noticed is that different EPs seem to suppress or make worse the CA that you get..I've recently got some really nice Meade Japan Series 4000 plossls at 32, 26 and 12.4mm and the CA is noticeably less with them than with others I've used. Also I have a nice Celestron Ultima 7.5mm and that is almost orthoscopic in colour purity.

As always my friend, a great read from your threads...keep em coming:headbang:

cheers

Dave

[John]

....As always my friend, a great read from your threads...keep em coming:headbang:

cheers

Dave

Thanks Dave, nice report yourself

It's Zeta Herc that I've now got my doubts about rather than Delta Cygni.

Another really challenging double I've found is Iota Leonis. It's not well placed now but worth a shot if you can. Like Delta Cygni, it's an unequal brightness close pair so can be tough.

[mdstuart]

The globular is M4..I saw Antaries rise over the gliders in N Wales last week which was amazng but no M4 visually so you had good seeing!

Mark

[John]

Had another go at Delta Cygni tonight with my C5 SCT and my 6" mak-newtonian. Got a nice split in both scopes - the mak-newt more clearly defined of course because of the additional aperture and smaller secondary obstruction.

I was rather pleased that the C5 managed it so well though - I've not had much luck with SCT's and binary stars in the past but the optics / collimation on this little scope seem well up to the task

As the C5 also showed me 4 craterlets in Plato and the Cassini Divison tonight I'm beginning to wonder if I need any other scopes !.