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Touring the 50mm/60mm Skies, Tour Number One: Cygnus, the Swan

We’re going to start our first tour with one of the most visually stunning delights in the heavenly vault, Albireo.   But first, we need to take care of an important matter that has to do with ornithological orientation.

For far too long I labored under the embarrassingly incorrect impression that the Swan wings it way through the night skies in a northerly direction.  In other words, I thought of the area around first magnitude Deneb as being the head, and Albireo as the tail.  But, as you can see in the attached artwork, courtesy of Stellarium, that’s not at all the case.

Hopefully Cygnus is flying well above that hungry looking Vulpeculan fox. A chart showing the locations of all the stars for this tour is just a few paragraphs below. (Stellarium screen image with labels added, click to see a screen-sized Swan)

So now you know, if you didn’t already.

The main thing, though, is that we are now OC — ornithologically correct —  which means we’re cleared to proceed.  😉

Albireo (Beta Cygni)  (Σ I 43)  (H V 5)       HIP: 95947    SAO: 87301
RA: 19h 30.7m   Dec: +27° 58′
Magnitudes: 3.2, 4.7
Separation:  34.8″
Position Angle: 54°  (WDS 2010)
Distance: 386 Light Years
Stellar Classification: K3, B8
Rating: Easy

Now it’s just possible that Albireo has been responsible for attracting more people to the beauty of double stars than any other star hovering above us.  If you’ve never seen it, here’s a sampling of two descriptions:

. . .  a stunning pair of deeply-colored stars, brilliant citrus orange and vivid royal blue, inside a dark cloud within a field packed with stars.” (p. 64 of Double Stars for Small Telescopes by Sissy Haas, 2006 edition)

“A bright double star on the Swan’s bill . . . topaz yellow . . . sapphire blue; the colours in brilliant contrast, by which term I do not mean the mere optical complementary tints, but relating to these bodies as radiating their own coloured lights.”  (pp. 449-450 The Bedford Catalog by Admiral William H. Smyth, 1986 edition)

If that doesn’t fire your desire to take a peek  ………..  well, just trust me, your embers will start to smolder at first sight.  And Greg has a DSC-60 post on it here, which is likely to fan those embers into flames as well.

So let’s aim these two small scopes skyward and see what we can see.

Now I’ll try to restrain my description to this:  stultifyingly stupendous  ——–  in both scopes.  The gold of the primary is as gold as gold can be, and the blue of the secondary isn’t too darn bad, either.  And Admiral Smyth was quite correct in calling attention to “these bodies as radiating their own coloured lights.”

“brilliant citrus orange and vivid royal blue” . . . “the colours in brilliant contrast . . .”. (Sky Safari screen shot with labels added, east & west reversed to match the refractor view, click to get even closer)

I used the 20mm TV Plössl (40x) in the 60mm refractor, and the 15mm version (36x) in the 50mm scope.  I prefer the low power view of this pair because there’s a special glittering quality to it.  The surrounding collection of sparkling stars look like they were just randomly scattered around the field of view by the wave of a stellar hand.  And Haas’s “dark cloud” is very evident — a black void immediately around the gold and blue pair that gives them an extra visual boost — not that they really need it.

But there’s a lot of light here, so you certainly can’t go wrong by adding as much magnification as conditions will allow.  If you’re new to this endeavor, try switching back and forth between something on the order of the 7.5mm view (which would be 72x in the 50mm scope, 107x in the 60mm scope) and the wide field view. You’ll notice the colors become more intense at the higher magnifications, but you lose the magic of the surrounding field.  On the other hand, there is something very addicting about watching the glow of those stars grow under the more magnified view, not to mention the appearance of a shimmering diffraction ring or two around each of them.

After you’ve let the magic of those gold and blue beams of light illuminate the darker corners of your photon enriched mind, we’ll migrate northward, away from the Swan’s head to it’s eastern wing, in search of a pair of tangerines.

We’ll use this chart for the rest of the tour, so don’t lose it! (Stellarium screen image with labels added, click to enlarge)

61 Cygni  (Σ 2758)       HIP: 104214    SAO: 70919
RA: 21h 06.9m   Dec: +38° 45′
Magnitudes: 5.2, 6.1
Separation:  31.9″
Position Angle: 151°   (WDS 2011)
Distance: 11.4 Light Years
Stellar Classification: K5, K7
Rating: Easy

Another easy pair — once you find them.  And that really isn’t difficult, if you’re careful and deliberate — so let me give you a hand here.

If you look closely at the chart above, note that 61 Cygni forms the eastern corner of a square with (in clockwise order) 1.3 magnitude Deneb, 2.2 magnitude Gamma (γ) Cygni, and 2.5 magnitude Epsilon (ε) Cygni.  Now at a combined visual magnitude of 5.2, 61 Cygni is the faintest member of those four corners, so it may help to take notice of the fact that 3.9 magnitude Nu (ν) Cygni lies about halfway between 61 Cygni and Deneb.  And it may be even more help to use 3.9 magnitude Tau (τ) Cygni as a reference pointer pointing directly into that faint corner where 61 Cygni lies in its dual state.

Now these are nowhere near as bright as Albireo, so be prepared for that.  Few double stars match that one for brightness and color — BUT — this is still a pleasing pair of tangerine tinted headlights beaming back at you from only  11.4 light years away.  I mean, if we had the means to get there at near the speed of light, you could make a round trip in something like 23 light years.

A seductive pair of orange headlights glowing from only 11.4 light years away! (Sky Safari screen shot with labels added, east & west reversed once again, click to get the full effect — seriously, it makes a noticeable difference in this case.)

But since that’s not meant to be for at least a few decades, I suggest you do the next best thing — go for the low power view.   It really works best on these two orange points of light of about the same brightness.  And, since these two are spaced apart at almost the same distance as the colorful Albireo pair, a bit of magnification works well here, too.  Be aware, though, that there’s about six times less light to work with in this case, so you’ll lose some of the impact of the color in these small aperture scopes.  But give it a try.

And after two easy pairs, let’s raise the level of difficulty a couple of notches, just to keep life interesting.

H IV 113 (Σ 2748)         HIP: 103822    SAO: 70818
RA: 21h 02.3m   Dec: +39° 31′
Magnitudes: 6.6, 9.5
Separation:  19.2″
Position Angle: 299°  (WDS 2006)
Distance: 1142 Light Years
Spectral Classification   A: K3
Rating: Moderate to Difficult

I thought I would throw this one in since it’s parked conveniently one degree to the west and slightly north of 61 Cygni, putting it in the same field of view in both of the scopes I’m using here.  For example, the 20mm TV Plössl in the 60mm scope gives me a 1.2 degree field of view, and the same eyepiece in the 50mm Zeiss provides a 1.8 degree field of view.  If you have a 25 to 30mm focal length eyepiece handy, it might help to put it to use here just to make it a bit easier to locate.

You can see H IV 113 holds down one corner of a triangle formed by 61 Cygni and 6.1 magnitude HIP 103894. Or, you can pan over to pick up Nu (ν) in your eyepiece, and as it comes into view, you’ll see that H IV 113 is the first of two sixth magnitude stars along that route, HIP 103641 being the other. (Sky Safari screen shot with labels added, click to enlarge)

Peering into the 20mm TV Plössl (40x) sitting in the 60mm scope, all I could see was the orangish primary — which by the way, is very similar to the colors of the 61 Cygni pair.  I’ve looked at this one before, so I knew the secondary was hiding within that orange glow.

I leaped ahead to the 11mm Plössl (73x) and glimpsed it with averted vision, and another jump in magnifying might to the 7.5mm Celestron Plössl (107x) brought it into direct view.  The only way I could see that 9.5 magnitude secondary in the 50mm Zeiss was to use the 7.5mm Plössl (72x), and at that magnification it’s weak photons were barely making their way to my waiting eyes — which is another way of saying it was an averted vision view.  Still, that view of the secondary in the 50mm scope was kinda neat — a weak, not quite focused blob of light that was very eerie and ghost-like.

H IV 113 in the moonlight shines with a noticeably orange glow, and if you look closely, you might see a hint of blue in the 9.5 magnitude secondary.  (East & west reversed to match the refractor view, click to lose this caption)

Now all of that took place on a night when the moon was about half full and on the opposite side of the sky (east) from where I was looking at Cygnus.  No doubt you could do better without the moon peering over your shoulder and stealing two or three magnitudes of faint light from the night sky — so don’t hesitate to give William Herschel’s gem an opportunity to grace your vision on a dark night.  The secondary has a traceof blue in it, which is just barely there in a dark sky in these small scopes.

So we’ll rate the difficulty on this one as moderate in the 60mm scope and difficult in the 50mm, with the proviso that a dark night will ease the difficulty by a half to a full notch.

And since I tormented your rods and cones a bit with that one, I’ll relent and shift back to easy again.  And this one is a real gem in every sense of the word.

Omicron-1 (ο-1)  (Σ I 50)  (H VI 10 — AC only)      HIP: 99675    SAO: 49337
RA: 20h 13.6m   Dec: +46° 44′
*****    Magnitudes   Separation  Position Angle   WDS Data
AC:         3.9,   7.0          106.7″                174°               2008
AD:         3.9,   4.8          333.8″                325°               2008
Distances:  “A” is at 1353 Light Years; “D” (30 Cygni) is at 717 Light Years
Spectral Classifications: All K2
Rating: Easy

Omicron-2 (ο-2)  (S 743)  (H VI 33)     HIP: 99848    SAO: 49385
RA: 20h 15.3m   Dec: +47° 42.5′
Magnitudes: 4.2, 8.4
Separation: 208.4″   (WDS 2002)
Position Angle: 177°
Distance: 1110 Light Years
Spectral Classification: K3, B3
Rating: Easy

Omicron (ο) Cygni consists of two pairs of doubles, labeled as Omicron-1 and Omicron-2.  And they’re as easy to find as they are to split.

If you look at the western wing of Cygnus, you’ll find the Omicron (ο) twins form a triangle with Gamma (γ) and Delta (δ) Cygni.  They’re an easy naked eye pair, although under a very bright moon or heavy light pollution, you may need binoculars to pick them out.  I have a 6×30 finder mounted on the 60mm scope, and in it, these two stars look like a pair of headlights shining across the thousand-plus light years separating us from them.

Again, start with the low power view, and you should be able to get both O-1 and O-2 in the same field.  They were a tight fit in the 60mm scope with the 20mm TV Plössl at 40x, but that eyepiece (27x) in the 50mm scope gave me a spectacular view, with each pair comfortably parked a respectable distance away from the edge of the field of view when centered, as in this sketch.

I much prefer the view of O-1, though, because of the color contrast — a gold and blue that remind me of Albireo.

The porthole view through a 50mm refractor, which is an ideal aperture for either Omicron-1, -2, or both at once.   (East & west reversed, click to lose the caption)

O-2 has those same colors in a slightly weaker version  ……………..

Just slightly less colorful than it’s other half, and even better when seen in the same field with it!  (East & west reversed again!)

……………..  but the view of O-1 is spiced up quite a bit by 4.8 magnitude “D”, which decorates the view with a rather pure white.  Actually, that star is unrelated to the other two, and has its own designation — 30 Cygni.  And you may have noticed that “B” is missing from the data line above — it’s there, shining at a weak magnitude of 13.4, well below the the threshold of our small scopes — but I left it out to avoid causing a stellar level of confusion.

There is certainly something about the view of Omicron-1 in the 50mm scope that totally captivates me.  If you can turn off the thought machine in your head for a few minutes and just stare at those fantastically colored orbs of light which seem to be perfectly arrayed against the background of black velvet and scattered stars, you can easily imagine yourself looking into deep space through the porthole of a space ship.  And if you’re using an un-driven mount, the sensation of slow movement through space is enhanced by the drifting of the stars across the eyepiece’s field of view.

Ahhhhhhhhhh  …………………………..  the magic of a dark night under the stars with those sparkling points of colourful penetrating light  —-  I could just sit here until dawn.

In fact, I think that’s just what I’ll do.


There’s another chapter in this series calling me from the northern reaches of the celestial sphere, so don’t touch that dial!  In fact, if you click on this link, Tour Number Two will appear on your screen faster than you can swap eyepieces under a full moon in June!


2 Responses

  1. Great tour, John! It’s always a delight to see these old friends afresh through your eyes. And I couldn’t agree with you more about Albireo. I got my first look at it while a college student using a 4-inch reflector close to half a century ago and I became a devoted fan for life. In fact it hooked me on double stars, though I went on to pursue many other astronomical interests, Albireo hooked me on the fascination of doubles.

    I never tire of looking at it and just the other night I got my first clean split with binoculars – uh, 60mm binoculars at 20X – and what startled me was the color.

    I have always seen Albireo as blue and gold. But this binocular view fit the Hass description perfectly – “brilliant citrus orange” for the primary. The secondary was certainly its usual blue, but the primary was as orange as orange can get with maybe a hint of rust. And no, that doesn’t mean the gold is tarnishing 😉

    Can’t wait for the next trip!

  2. I, too, enjoyed this post and although Cygnus is rapidly setting as winter continues, I have some of these on my observing list to revisit. I particularly enjoy your discussion of eyeieces as I’m shopping for a good 15 or 18 mm E. P. to contribute to my selection. I use a Pl. 26mm for sketching and an astrometric 14mm for Theta & Rho calibrations now. I guess I fall I’m the apature hog catagory with my C925 which yields 90X w/ my 26 mm..

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