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The “Original” Double-Double: Epsilon (ε) Lyrae

Epsilon (ε) Lyrae
RA: 18h 44.3m   Dec: +39° 40′

Epsilon-1/AB  (Σ 2382)  (H II 5)    HIP: 91919   SAO: 67309
Magnitudes:  5.15, 6.10
Separation:   2.3″
Position Angle: 346°   (WDS 2013)
Spectral Type:  “A” is A3,  “B” is F0
Distance: 162 Light Years (Simbad)

Epsilon-2/CD  (Σ 2383)  (H II 6)    HIP: 91926   SAO: 67315
Magnitudes: 5.25, 5.38
Separation:  2.4″
Position Angle:  78°  (WDS 2013)
Spectral Type: “C” is A^, “D” is F7
Distance: 160 Light Years (Simbad)

Epsilon (ε) Lyrae forms a triangle with Vega and Zeta (ζ) Lyrae. Shown here as slightly elongated, it’s easily transformed into four stellar points of white light in even a 60mm scope on nights when the seeing is steady. (Stellarium screen image with labels added, click on the chart for a larger view)

June 22nd, 2010

After being lured out several nights for the past week by hopes the clouds would give me a break for half an hour or so, I decided to give it another try tonight. The sky was about seventy percent overcast, so at least there was a slim hope.  And, like the last few nights, as soon as I was set up and ready to go, the sky gods drew their blanket of clouds back across the stars, chuckling to themselves as the last few bright spots disappeared.  But, with a cup of tea in my hand, the ocean humming away in the background, the moon playing hide and seek in the trees to the southwest, and the temperature a mild fifty-five, I decided to stay put and just enjoy the night.

After I sat there for about thirty minutes, the clouds thinned enough that I could see Vega, so I pointed the finder on my 90mm refractor at it and poked around until I found Epsilon (ε) Lyrae.  Now, if you’ve never done this — and this was my second time — you’ll be amazed both at what you can see and how stable the atmosphere is.  The overcast has to be thin enough that you can see at least first magnitude stars, and the clouds should be moving at just a crawl — but — under these conditions, the seeing can be very good.  My first view in the ninety was with a 20mm TV Plössl (46x) and I could just begin to see some separation between each  of the two stars in Epsilon-1 and Epsilon-2.  Replacing that with a 15mm, which increased the magnification to 61x, they were clearly separated.

Orion 90mm pointed into the clouds at Epsilon (ε) Lyrae

So, with the evening being so pleasant, I just watched the four stars as the clouds drifted by.  Sometimes they would almost disappear from view, other times they would suddenly brighten as the clouds thinned out.  Most of the time, they were about halfway in between.  But the seeing was as steady as a rock the entire time, so it was pleasant to just look at the two doubles staring back at me without quivering in the least.

June 23rd, 2010

Now, this is more like it!  A totally clear sky and not a breeze anywhere near!  My plan tonight was to sample of few of the sparse offering of doubles in Ursa Minor, but I noticed the sky was much darker to the northeast, so I pointed my scopes at Epsilon (ε) Lyrae again.  And, believe it or not, I spent the better part of an hour here and even after that length of time, I had to force myself to move on to something else.

Tonight, I had a 105mm, f/15 refractor aimed at Epsilon (ε), and riding on the back of the long refractor was a miniature copy of it, a 60mm f/16.7 that I put together from parts.  The moon was out and about ninety percent full, but it was hugging the southern edge of the sky, and most of it’s glare was blocked by some tall fir trees.  So even though it was bright, it was behind me and low enough not to be scattering light all over the sky.

Now, as satisfying as the previous night had been, tonight’s first glance into the 18mm (83x) eyepiece in the larger refractor left me frozen in place — although I think an involuntary expletive deleted might have slipped from my lips — but I was so stunned, I can’t honestly remember.  In the eyepiece, the sky was pitch black, and the four components of Epsilon (ε) Lyrae were four bright white pin-points of light that looked as if they were hovering above the blackness, and scattered at the edges of the eyepiece were fainter stars that accentuated the three dimensional effect.  After the haze of the previous night, and with the larger scope gathering more photons, plus the wider field of view in the eyepiece, the image was absolutely razor sharp and vibrant.  Multiply very pleasing by a factor of twenty and you get close to what I saw.

But it got even better when I compared it with the 60mm scope.  I put a 20mm TV Plössl (50x)  in that one and saw two white pinpoints on each side of the eyepiece that were touching, so I replaced it with an 11mm version of the same brand (91x) and could begin to see some black sky between them.  A 9mm UO Ortho (111x) put a definite border of black sky between the close components.  As satisfying as it was to split Epsilon (ε) with a  60mm scope, I kept going back to the view in the larger scope because of the three dimensional effect.  There was such a contrast in image brightness between the two that I just couldn’t resist looking at the view in the 105mm again and again and again. The difference in light gathering ability of the two scopes was a huge factor in enhancing the view in the larger one.

And once again the seeing was very stable, so I decided to push the magnification on the 60mm to see what it could do.  I thought I would go for broke and jump to a 4mm Astro Tech Plössl (250x), but it was just a bit too much.  All four stars were there, but the focus was very soft, although for very brief moments, they would snap into focus.  I moved back to a 6mm AT Plössl (167x) with much better results — four nice round globes with just a bit of unevenness around the edges, surrounded by those mesmerizing diffraction rings.  Not one to give up quickly, I replaced the six with a 5mm UO Ortho (200x) and found the view was about the same.  But the highlight of the night was when I removed the 5mm and put it in the larger scope, which gave me a view at 300x that was very similar to the one in the 60mm, only much brighter.

And then I remembered there was another “double-double”in Lyrae, so after more than an hour of very pleasant and rewarding viewing, I pointed my stack of scopes in a more southerly direction.

Continued here!

(WDS data updated 9/9/2014)


2 Responses

  1. This is my favorite double. I check it just about any chance I get – it’s become a guide to seeing conditions for me. But I’m usually using a larger scope. In the 127mm under most conditions, you are guaranteed a beautiful split. But this morning was the first time I’ve gotten a really clean split of it with a classic 60mm scope – something John reports doing with a certain nonchalance above.

    With transparency at about mag 5 and seeing well above average, I turned the Unitron 114 to the Double Double and slowly increasing the power I saw the pairs elongate, then cleanly split with black sky between them at 125X. I was using the 7.2mm TV PLossl, the shortest focal length in that set. I could have gone with a higher-power Nagler, but that would have meant going inside and compromising my dark adaption, which I didn’t want to do.

    Instead I put in a barlow and with the 10.5 mm got a somewhat better split. That didn’t feel that right to me, however, for the combination involved readjusting the drawtube and it all looked somewhat awkward. There’s a certain elegance that seemed important to me this evening. I ha d a simple, high quality, classic scope and simple, high quality, classic eyepices. What I really wanted at this point was the 6-3mm Nagler zoom that I bought on Astromart yesterday, but won’t be here for several days!

    Now that’s hardly a classic. In fact, it’s less than 10 years old. But it has the virtue of being small and thus not feeling like it overwhelms the scope on the eyepiece end. This was one of those nights when that would have been the perfect combination for this scope.

    Is splitting the Double Double a major challenge for a 60mm? John seems to take it in stride in his report above, so I’m not sure. He has much more experience with these classic scopes than I do. But at the least I would callt he Double Double a “challenge” object for a 60mm scope.

  2. Interesting – I had a new (to me) Tak LE 7.5mm to try – I wanted to see if it was as good as the Tak LE 5 I had gotten recently. It is. But what fascinated me was this. With the 5 I have the exact equivalent in a Nagler to test it against – 5 vs. 5 – and it comes out a draw.

    With the 7.5 the closest Nagler I have is a 7. So i aimed the Orion 110 ED at the Double Double which was near the zenith in twilight. The Tak 7.5 at 103X split it – but the Nagler 7 at 110X did it better. And that’s what surprised me – that I could really see a difference between 103X vs 110X. Of course it could be that the Nagler is better, but I don’t think so. I think it performed better in this instance simply because of the slight increase in power that it delivered.

    As it got darker and the air calmed down a bit more, the Tak did better – but the slightly more powerful Nagler stayed ahead of it.

    When I tried them both about 45 minutes later on Mu Draconis there was no doubt that they both performed equally – but there the split wasn’t quite so difficult. Bottom line. I’m happy with the two Taks I have and I will acquire more. They have good eye relief, they’re light weight, and while the apparent field is just 52 degrees, I would take them over my TV Plossls for comfort.

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