Epsilon Lyrae - The double double

[Llamanaut]

Had a crack at splitting the double double last night but found i couldnt Vega was giving off a glare (could have been atmospherics) and the full moon certainly didnt help. Ive read that the double double is relatively easy to split...Does anyone have any tips?

[kniclander]

it is "relatively easy" if it is high in he sky, the air is still and the scope is well collimated. Otherwise it is relatively bl**dy hard... Unless you were out very late, it may well have ben too low. Also, you need quite high power, say 150+. For some reason my little refractor splits it much easier than my big dob and in the little frac the dfferent colours of one of the pairs shows up really nicely.

[Doc]

It's not that easy if you don't pump the magnification up. I also find this easier in my TAL 100r then I do in my 16" dob, which I find a bit strange. Use at least x200 maybe more and the higher the better as well.

[brianb]

It's not that easy if you don't pump the magnification up.

Hmmm. The two pairs are both over 2 arc secs seperation, you shouldn't need all that much power to see them seperated - x56 on my first scope (a pretty nasty 60mm refractor, over 40 years ago) was sufficient to seperate; x112 showed "black" space between the diffraction discs.

Large scopes can make the task of seeing "black space" more difficult as the individual starts become bright enough to contribute glare. But if you aren't seeing a seperation with any decent scope at x100, you have an issue with optics or bad seeing. But don't automatically assume optics; you can't in any case judge optical quality or make minor adjustments to collimation unless the seeing is at least reasonably steady.

[John]

Tight doubles are a really good test of collimation. Personally I much prefer using my 4" and 6" refractors for doubles - the 4" splits Epsilon Lyrae fairly easily at 186x, the 6" provides a wide and easy split of the 2 pairs.

[Doc]

Looking back through my notes all my observations of Epsilon Lyra have been through the TAL with my 6mm ortho giving x166 and I've put managed to clearly split and see darkness between components.

[Llamanaut]

i made sure collimation was on the money last night and i did find that the 12" made smaller stars 'stand out' more producing glare. When i defocussed on a bright star i got a perfectly central donut (i even got the three evenly spaced clips) so i dont think collimation is a problem. I started viewing Lyra at around midnight so it was pretty high by then, although the moon was washing things out. Hopefully i'll give it a go tonight with my 70mm Bresser and report back. Thanks for the advice

[russ]

I gave this a go last night while doing a mini review of the Celestron 102. Funnily enough both refractors managed the split far better than the 8" dob. I very rarely use the dob for doubles. I find the 90mm achro a far better tool for the job. When looking at doubles everything about the view in the 90mm is superior to the 200mm dob. Tighter stars, nicer star colours and better separation. It's the one area where the much bigger reflector struggles to compete.

[Macavity]

I sense it depends mostly on "seeing" and somewhat on scope quality. I am sure I have split both components with my (onetime) MAK90. But I tried for quite a while, until the conditions were just right - Then it was easy. I can usually split it (via brute force?) with my bigger MAKs, but frankly the image quality is no better. More aperture equals more aberrations, I reckon...

[Talitha]

On two consecutive nights this week (Wednesday and Thursday), i had two different results using the 120ST. Both nights, the target's altitude was only 32 degrees above the horizon, and magnification used was 187x (9mm ortho and 2.8x barlow).

On Thursday night i couldn't even squeeze a peanut shape out of the pairs. But on Wednesday night there was blackness between the components. Not enough to drive a bus through or anything, but definitely enough to swipe a credit card.

I've found the same thing to be true using the 8" SCT on consecutive nights, so for me the seeing is what's most critical.

[Moonshane]

you could try a ND (moon) filter as this often increases the apparent split in some doubles by reducing the glare a little. also, a little fine cloud high up can help too - that's a bit harder to arrange than a moon filter though

I too find the sharpness of my refractor helps on some doubles but not others. I can usually split with the dob though with no major problems and I am sure you will too in due course.

[lunator]

I look at this pair on a regular basis and any magnificaton over x100 should be good.

One pair is certainly harder than the other.

I guess the atmospheric seeing could be a factor.

Cheers

Ian

[Moonshane]

One pair is certainly harder than the other.

because of this thread I had a quick look last night. the seeing was pretty bad with high cloud (which may actually have helped) and they split relatively easily at most mags in the dob. The focusing is quite critical with the dob (one of the reasons I got a SW dual speed crayford - will be fitting this tomorrow).

good luck when you next have a look - you'll be able to do it eventually.

[Peter Drew]

Make a cardboard mask with a 3" or 4" off axis aperture and tape it on to the front of your 300mm scope. You should find that E1 and E2 will split most times.

[Talitha]

Because of the wider spread of magnitudes, Epsilon 1 (northern pair) has always been the more difficult one for me to split. Here's a single digital image from a few years ago (8"SCT).. you can see the magnitude difference quite easily.

[lunator]

Here is a pic I took a couple of years back using my compact camera.

It gives a very similar view to what can be seen visible.

Cheers

Ian

[Stu]

Just to add to the refractor comments, I've just about split the double double with a WO 66mm at the highest power I could get - if I remember correctly a barlowed 7mm nagler ie round x110

[albedo0.39]

Splitting this one requires good seeing conditions and last night was not ideal (skies were not that steady depression over the UK).

As many people have mentioned, collimation has to be spot on - even in larger scopes and whilst I've split it in my 16", it doesn't show itself without a fight.

Good luck and well done to all those people splitting in smaller scopes.

[Doc]

Splitting this one requires good seeing conditions and last night was not ideal (skies were not that steady depression over the UK).

As many people have mentioned, collimation has to be spot on - even in larger scopes and whilst I've split it in my 16", it doesn't show itself without a fight.

Good luck and well done to all those people splitting in smaller scopes.

This is exactly right Steve. I have also split this in my 16" dob, but collimation and seeing needs to be precise. IMO it's so much easier in a refractor

[Peter Drew]

The main problem with splitting Epsilon Lyrae is that it's too bright for large apertures which suffer more from all the factors that normally afflict a telescope. Most small refractors and 4"-4.5" reflectors of decent quality should have little trouble with the split on a suitable night. It's most frustrating when your main instrument struggles with this feat and I'm sure that this is where reflectors get some of their "inferior" reputation compared to refractors. I would wager that a 16" would easily split a pair of mag 12 stars at the same separation.

[Talitha]

Thanks for that info, Peter. I'm seriously considering a 12" or 14" Dob in the near future, and it's good to know that i shouldn't be too upset if it doesn't do as well as my 120ST on bright doubles. Splitting mag 12 stars sounds awesome, though.

[Sam]

Go for it Carol! you'll not regret the aperture. I've found the double double quite easy to split in my 16" - good collimation is very very helpful. I used to use it as a test for how conditions were.

[philj]

I recommend a refractor every time for doubles.

My 4" F15 vintage will split the pair easily at 90 - 100x. My little 60mm Swift (Takahashi optics) will also split it when its high in the sky with 100X plus, below that you can tell the orientation of the pairs but no separatation.

So its not aperture that counts

Philj

[Talitha]

Go for it Carol! you'll not regret the aperture.

Still need more info before deciding, but you'll know if/when i do.

[John]

There is another "double double" in Lyra you know .......as I found out tonight, thanks to my excellent constellation guide. E2470 and E2474 Lyrae at 13.4" and 16.2" respectively can be resolved with 16x70 binoculars on a really good night and make a nice double pairing at around 100x with a scope.