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A Veiled Double – 52 Cygni

Cygnus, in all its spread out glory, as it flies through the Milky Way. 52 Cygni can be seen left of lower center. (Stellarium screen image with labels added, click for a large view)

Located at the base of the east wing of Cygnus, the Swan, 52 Cygni marks the location of the southern segment of the Veil Nebula, which is also known as NGC 6960.  I suspect most people who have looked at it have focused all their attention on that long thin strand of nebulosity that extends on both sides of it without realizing that it’s a double.  That was certainly my experience until I found it listed in Sissy Haas’s Double Stars for Small Telescopes.

The last time I looked at this beautiful double was in the middle of July.  At the time, I had intentions of writing something up on it, but I wanted to get one more look at it first.  Little did I suspect that the cloud and fog gremlins were about to join forces and put me out of business for almost a month.  But the morning of August 13th dawned bright and clear, and with it came a balmy temperature of ninety-five degrees – which was intense enough to burn the leaves on many plants, like my rhododendrons, to a brown crisp. On the other hand, it was clear when the sun went down, and unlike the evenings of the past month, it stayed that way.  At 10 PM it was still a very warm eighty-four degrees, though, which is a bit brutal in a coastal town that hasn’t seen eighty degrees in the daytime – much less at night –  since early June.  When I gave up about 3 AM the temperature had crawled all the way down to a mere seventy-eight.  I went to bed with a window open and a fan pulling air through the bedroom – and woke up at 4 AM freezing to death.  Outside, the sky was clouded over, fog was rolling up the street from the ocean, and the temperature had plummeted to fifty-four degrees!  End of clear skies for how long??????

What does this have to with 52 Cygni?  Clear and warm as it was, that hot air was already being disturbed by the cool air lurking off the coast, causing horrible seeing.  Most stars boiled and shimmered so badly that focus was impossible beyond 50x, so looking at doubles was pretty much hopeless.  Jupiter had a glow around it, which was a clue that there was some moisture up there somewhere, even though the air felt like sand paper.  However, the transparency was still pretty darn good, so I began looking at deep sky objects.  At the top of the list was the Veil Nebula, and I figured I might as well see if I could split 52 Cygni.  Fortunately, it was high overhead, which gave me a decent chance.

52 Cygni  (Σ 2726)  (H II 25)          HIP: 102453     SAO: 70467
RA: 20h 45.6m   Dec: +30° 43′
Magnitudes: 4.2, 8.7
Separation:  6.0″
Position Angle: 70°  (WDS 2006)
Distance: 206 Light Years
Stellar Classification: G9

The 6.4″ separation of the two stars would lead you to believe this is an easy split, but the 4.5 magnitude difference between them makes it a bit tougher than that.  I was using a 20mm eyepiece in my six inch refractor, which gave me a magnification of 76x.  As I got my first look of the night at 52 Cygni, I could see the nebulosity flowing from both sides of it.  I needed a bit wider field of view to take it all in, though, so I switched to a 30mm eyepiece, resulting in a magnification of 51x.  The view of those long, thin filaments of nebulosity was just stunning – and without the use of an OIII filter even!  For a moment I forgot that it was the double I was looking for!

This Stellarium screen image provides some idea of how small and close the secondary is, shown here almost out of sight at the TOP of the primary, not at the lower left. (Click on image for larger view)

Now this is one of those stars that will tease you.  The first time I looked at it, I looked and looked and could not see the faint companion.  And then suddenly after staring at it for about ten minutes, I realized I was looking right at it!  It’s a very small pin point of light nestled up very closely against the much brighter primary.  The best way to describe the effect is to compare it to the view of Polaris in a 60mm scope, the faint companion of which can easily be seen with good 60mm optics on a night of steady seeing and average transparency – but, you have to look very closely in order to see it because there is a full seven magnitudes of difference between the two stars.  And, as with 52 Cygni, you’ll often find you’re looking right at it without really seeing it until some quirk in the brain quits quirking and allows you to recognize it.

At 51x, I could just detect the secondary’s 8.7 magnitudes of faint light, and yet it was cleanly separated from the primary.  Switching back to the 20mm, in moments of steady seeing it was very easy to detect.  On this particular night, the primary was clearly a dark orange-yellow, which is the first time I’ve seen that tint.  I don’t know if it was the atmosphere or the scope.

Here are my notes from the other side of the cloud-fog-gremlin divide:

July 15th:  In a 102mm f/15 refractor, the secondary is a very small pin point of light at 94x; primary has a red tinge to it.  Also clearly seen and split in a five inch f/9.3 refractor at 74x.  In a 60mm f/15 at 50x, the secondary could not be seen.  Averted vision brought it out at 100x, but 150x and 225x made it more obvious – although it was still tough even at those magnifications.

On the west wing of Cygnus is another tough customer, Delta Cygni, which is actually much tougher than this one — you can read about it here — and keep reading into the comments because that’s where the real saga of that devious double takes place.

At any rate, on both wings of Cygnus what you’ll find are built-in challenges just waiting for you to sharpen your observing skills!  Don’t wait — clear skies in these parts don’t last long!

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3 Responses

  1. Thanks, John-particularly for the detailed info. on this excellent and tricky double. Had v. good transparency last night AND the seeing was IV . Got a great view – very like Polaris as you said. Had to use 150X in my ED 80 on 52 Cyg to get the same view of Polaris at 67X. Despite using lower powers and an UHC filter have still yet to detect “The Veil”. Made up for it with a steady split of Mu. Another great piece of sky. Clear skies, rich.

  2. You’re having more luck with Mu Cygni than I’ve had lately, Rich — tried to get it with an 80mm f/15 last night, but couldn’t quite get there because of the seeing. Might have had a glimpse of it, but only barely.

    The Veil Nebula is certainly elusive, no doubt about that. You definitely need a dark sky and better than average transparency to see it. But it’s like a lot of other elusive objects — once you’ve seen it, it becomes easier the next time. Low power and a UHC filter are the right ingredients at least, so don’t give up.

    I remember seeing the larger sections of the Veil northeast of 52 Cygni for the first time in a TV102 with a 20mm Nagler and I couldn’t believe it — it was so obvious that night that I was just amazed I had never seen it during earlier attempts.

    The strands of nebulosity on either side of 52 Cygni are a bit more difficult, but I’ve found moving the scope back and forth slightly, or bumping it to get some vibration, will help it to appear — along with the use of averted vision. I’ve had a few rare nights where it was visible even when looking directly at 52 Cygni — which is spectacular.

  3. Thanks John for the info and tips to see The Veil. I started with 52 Cyg so that i had a definite spot to look around as carefully as poss. Now i will go NE to try the larger (and maybe easier!) sections. Good luck and regards, rich. BTW i recently took a leaf out of your book -and Greg`s- and bought the S&K Pocket Sky Atlas. Fabulous!

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