A Double star challenge Epsilon Lyrae.

[SiriusB]

Mods~ hope this is ok, feel free to move. Thought it might be interesting for beginners?

For Beginners:

Epsilon Lyrae is a double double star. If you haven't already seen it, please try to find. Currently riding high in the sky.

Your challenge is:

                              With your telescope, what's the minimum magnification you can resolve it into it's four components? 

And for the purposes of the challenge,I mean a clean split, & by that i mean you can see dark sky between all four components (google 'Dawes limit' for more info)

Now i did set myself this challenge a few years back,using 80mm & 100mm but i've forgotten the details now, so i'll be out with my ED 80 in due course.

FYI, Splitting the double double is possible in an 80mm, maybe even a 60mm?, so most telescope owners should be able to partake.

If you're the lucky owner of a 200mm apochromatic  refracto & have the eyes of a hawkr, you'll probably resolve at lower mag than the rest of us, lucky you.

THERE ARE NO RIGHT OR WRONG ANSWERS! But it may help hone your observing skills.

Don't worry if others post lower magnifications at a given aperture. It doesn't necessarily  mean your eyes or telescope is bad. Practice & you'll get better.You are training your eye.

& if you're  genuinely bad at double star resolution, you may have good planetary resolution skills (i haven't!) or maybe your eyes pick up faint nebulae well? Were all made a little different.

Tips for beginners:

When the atmosphere is steady you'll find splitting double stars easier.

One pair is a lttle easier to seperate than the other pair.

Often,splitting double stars is something listed as something "to do" around full moon. True, but a little easier when the moon is less bright none-the=less.

I suspect of the factors affecting the result, seeing is the most important, visual acutity the 2nd, with telescope type & optical accuracy trailing behind.

Please post Telescope aperture, type & magnification used.

Hopefully we'll all learn something.

Sub challenge:

No telescope? No problem. Can you split Epsilon Lyrae into 2 components with the naked eye?

Meant to be semi difficult.

FWIW When i was younger, under a darkish rural sky, i found this not particularly difficult. Now older, & under suburban skies, it's no longer possible.😞

[SiriusB]

Ps. No cheating! Just be honest, no prizes, it's a challenge, not a competion!

I know i've got pretty average eyes & pretty average scopes.

Look forward to the results with interest.

[Pixies]

Cool idea.

Bresser Messier 8" Dob. My first attempt back in April would have been a failure at 200x (with my starter 6mm plossl). Then after learning to collimate better and fixing a mirror problem, I could split them at x200 (6mm ortho).

But back then I had a more limited range of EPs. I could split one pair but not both at 68x (18mm EP). I had nothing inbetween.

I'll have another shot when the sky is clear next - assuming Lyra is still around by then!

Edited July 29, 2020 by Pixies

[John]

Good idea !

Finding the lowest magnification that they can be split with in a given aperture is a good challenge for the observer, the seeing conditions and the scope optics

[Pixies]

This is what a zoom EP would be useful for!

[John]

1 hour ago, Pixies said:

This is what a zoom EP would be useful for!

Yes, very.

 

[Merlin66]

Ok.

I cleanly split the double double while in Belgium.

Using a 4" Genesis with a 10.4mm Plossl (x49)

(I believe some others have actually managed with a slightly lower magnification - there was a thread a couple of years ago)

 

[Geoff Barnes]

1 hour ago, Merlin66 said:

I cleanly split the double double while in Belgium.

Using a 4" Genesis with a 10.4mm Plossl (x49)

 

I'm staggered by this, 49x??? Whilst the double double is very low down here near the horizon and very wobbly, I have just about managed to split them into four on a couple of occasions with my 12 inch Dob but only with around 180x-200x.

[jetstream]

Naked eye split- yes no issues here.

2 hours ago, Merlin66 said:

(I believe some others have actually managed with a slightly lower magnification - there was a thread a couple of years ago)

My TSA 120 goes a squeak lower mag.

[Merlin66]

Steady seeing, good optics and practice..... that's the challenge.

[Barry-W-Fenner]

I got them last night just as the sky was getting dark about 10pm. So more dusky still really. I thought they would be a good test in the 12" dob with the new 14mm Morpheus. I could see the split in both pairs at x107 mag.  I though this was pretty good as the sky was doing a Mexican wave last night and very wobbly. 

More to follow on the 14mm morp in another thread!

[Barry-W-Fenner]

2 hours ago, Geoff Barnes said:

I'm staggered by this, 49x??? Whilst the double double is very low down here near the horizon and very wobbly, I have just about managed to split them into four on a couple of occasions with my 12 inch Dob but only with around 180x-200x.

Hi Geoff,

EL and lyra in general are very high for us at the moment. Almost at the zenith at times.

I managed the split in my 300p last night at x107 in very wobbly seeing conditions. I guess us dob owners also have the slight disadvantage of good old defraction spikes to contest with aswell. 

Baz

 

[Knighty2112]

As soon as I am back home from work at the weekend (and clouds permitting) I’ll get both my 80 ED ‘frac and larger 120mm ‘frac on the case. Also with the 10” Newt. 

[Saganite]

Trawling back through my Astro records, I note that in August 2018 ( I do recall the thread that Merlin 66 refers to a couple of years back and my notes appear to coincide), I split Epsilon Lyrae with my Tak FC100 and a UOVT 12.5mm  eyepiece at 59x.

Edited July 30, 2020 by Saganite

[chiltonstar]

I can usually split them (180 Mak) at around x108. Worth noting that "split" is quite difficult to define, and what many of us see as split might not be to others.

There is a formula which allows you to calculate minimum magnification: for a person with excellent acuity and with stars of equal magnitude, it is about 130/separation, or about 200/separation for many of us. Assuming somewhere between the two, Epsilon Lyrae would need about  x72 magnification.

Chris

Edited July 30, 2020 by chiltonstar

[Merlin66]

Train your eye. Concentrate on the image, hold your breathe and pump the oxygen to the brain.

When you can split the double double, OK, move to a lower magnification. Take your time - train your eye.

[Geoff Barnes]

1 hour ago, chiltonstar said:

Worth noting that "split" is quite difficult to define, and what many of us see as split might not be to others.

True that.

I have to say in my defence I don't consider it a split unless I can see clear black sky between the pair, and despite my poor viewing conditions there was clear seperation around 200x.

[Merlin66]

A thin black thread separation is the “minimum “

Takes time, this is not a 30 second challenge.

Good practice to train your eye. It’s a bit like running....everyone can run, but few have the dedication to run properly. Takes practice and rigor and some dedication.

The more you look......the more you see.

 

[chiltonstar]

12 minutes ago, Merlin66 said:

A thin black thread separation is the “minimum “

Takes time, this is not a 30 second challenge.

Good practice to train your eye. It’s a bit like running....everyone can run, but few have the dedication to run properly. Takes practice and rigor and some dedication.

The more you look......the more you see.

 

But of course, you can't beat the limits set by aperture and resolving power. 

Chris

[Merlin66]

Obviously a 100mm aperture, under good seeing, and good eyesight, are capable of resolving this double double.

 

[chiltonstar]

Just now, Merlin66 said:

Obviously a 100mm aperture, under good seeing, and good eyesight, are capable of resolving this double double.

 

Yes, with good seeing it is of course an easy pair of pairs to split with my 102mm f13 frac.

Chris

[John]

Last night I managed to split both pairs of Epsilon Lyrae with a 90mm F/11 refractor (cheapie !) at 74x. I was using a 7.2- 21.5mm zoom and gradually adjusting until I could just see the thin black gap between the star pairs.

I got Pi Aquilie with the scope as well but that needed 180x !

I use these guidelines when I'm working out whether I've got a split or not although I sometimes also throw in the terms "snowman" and "peanut" because that's what not-quite split sometimes looks like !

The above pairs were clearly "split" to me last night (and a few others too):

[markse68]

5 hours ago, Geoff Barnes said:

I'm staggered by this, 49x??? Whilst the double double is very low down here near the horizon and very wobbly, I have just about managed to split them into four on a couple of occasions with my 12 inch Dob but only with around 180x-200x.

I bet you have no trouble with Antares though!

[Saganite]

2 hours ago, chiltonstar said:

I can usually split them (180 Mak) at around x108. Worth noting that "split" is quite difficult to define, and what many of us see as split might not be to others.

There is a formula which allows you to calculate minimum magnification: for a person with excellent acuity and with stars of equal magnitude, it is about 130/separation, or about 200/separation for many of us. Assuming somewhere between the two, Epsilon Lyrae would need about  x72 magnification.

Chris

Well, I guess based on this, and John's excellent chart, I didn't split them but  merely resolved them, though at the time I certainly felt that I had. With a difference of  13x magnification it would have been a very fine line.....

[Geoff Barnes]

37 minutes ago, markse68 said:

I bet you have no trouble with Antares though!

Indeed, nice and high in our sky and quite an easy split as I recall from last year, though I don't remember the mag required.

Coming into view here soon so looking forward to splitting it again.