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The Polaris (binocular) challenge – a learning exercise for new Splitters and a warm-up exercise for experienced ones

Polaris (Alpha [α] Ursa Minoris) (Σ 93)
MG: 2.0, 9.1  Sep: 18.2″  PA: 232°  (WDS 2009)

You can take this as a challenge, a lesson in splitting, or a warm-up exercise to use any time you feel like it  before moving on to something new.  For Northern Hemisphere observers Polaris is perfect in this respect because it is available every night, all night,  and stands virtually still. What’s more, it is not only a good challenge for binoculars, but also for any small scope.

Conclusions first

For me it has been all these things, but most importantly it has been a learning experience. I won’t keep you waiting – here’s what I have learned by taking the Polaris challenge:

  • I can easily split Polaris at 30X
  • I can intermittently split Polaris with 20X80 mounted binoculars in average conditions
  • All the numbers we use  – I use – are approximations, so don’t get anal retentive about them unless you have done a thorough, optical analysis of your equipment. (Something that is beyond my knowledge and patience.)
  • My binoculars say “20X80” on them. The effective objectives are really closer to 72mm, not 80mm –  that much I can measure.
  • I have  developed a simple, sure-fire way to always know where Polaris B should be
  • I have found that splitting nearby Mizar, with stars much more closely matched, but separated by 14 seconds instead of 18 seconds – is a great warm-up to splitting Polaris.
  • All the other general rules for splitting apply in spades –
    • be comfortable
    • be well rested
    • be fully dark adapted
    • focus with extreme care
    • position your head carefully in line with the eye lenses
    • spend time on target
      • look for at least a solid minute at a time

And now the details – how I got there from where I was

I start as a 70-year-old star splitter who has never sought the challenges John routinely takes on, but who has over half a century split more double stars more times than I care to remember and at the top of my list of stars frequently split is Polaris. I do a lot of outreach and I almost always include it in the show, usually using at least a six-inch scope so my  visitors have no trouble seeing that little faint dot next to the second magnitude primary and reminding them then that if our Sun were placed at the distance of Polaris it would be a bit fainter than the  secondary – Polaris B.

Recently I finally made a breakthrough splitting doubles with binoculars – something that was a real eye opener for me – and I was hooked on the kind of delicate images – and  elegant splits you get at low power – or any time your splitting takes you into the realm of the improbable. So I had to see if I could split Polaris with binoculars. And I thought I did on my first try with 25X100 Zhumells – only when I checked our own web site to remind myself  of the position angle  (pa) of Polaris I found that my supposed split was simply wrong – way wrong – 180 degrees wrong!  Now that is embarrassing to an experienced star splitter – but it came because I was really under estimating what I should see and because I didn’t have an easy way to know where to look for Polaris B.

Knowing where to look is a special case – and I have since seen writings where experienced observers screw it  up – because Polaris is rotating around the North Celestial Pole just like every other star – so Polaris B will, in the course of 24 hours, appear to rotate about Polaris. All this means is to use the Position Angle of 232 degrees for Polaris you have to apply the same two rules that you apply to any star:

  • west is the direction the stars appear to be moving
  • north is the direction from the primary towards Polaris

Whoops! Can’t use that second one here because we’re looking at Polaris. So which direction is true Celestiual North when you look at Polaris? To answer that find the crude asterism known as the “engagement ring” – those  stars will always be to the south of Polaris and the position angle of the brightest star in the ring is darned close to the position angle of Polaris B – all of which should become clear as you study this chart.

Low power finder chart for Polaris B showing field for 20X80 binoculars. Polaris B is at almost the same pa as the star marked 64 - brightest star in "Engagement Ring" asterism. Click for a larger version. Developed from Starry Nights Pro screen shot.

The preceding chart serves as a guide in two keys ways – first, use it to know where to look for Polaris B.  The secondary is, of course, much closer to Polaris than any of the stars shown, but with a pa of 232° it is for all practical purposes in the same direction as the brightest star in the Engagement Ring marked 64. Using Starry Nights Pro software I measured the PA of that star from Polaris as 229° – so Polaris B is just a tad  west of this line.

Not rocket science, but not easy – it pays to sneak up on this one

Knowing that Polaris B is magnitude 9.1, it helps to first find the other numbered stars on this chart. The numbers follow the standard convention for showing magnitudes on a chart in that the decimal point is left out – so the star marked “90” is of magnitude 9.0. Since Polaris B is impacted by the glare of Magnitude 2 Polaris, I used the 9.8 magnitude star as my rough guide to know what to expect to see.

The next question was, however, just how close should I expect Polaris B to be – and for this I took two approaches. First, I did a warm-up exercise with a Televue 85mm. I started at 85X with a 7mm Nagler. My eyes weren’t fully dark adapted and the night was far from perfect, so it took a few moments for Polaris B to pop into view even at that power – but it soon was shining steady and obvious right where it is supposed to be and you wonder why it wasn’t always so obvious.  I then dropped the power systematically, staying on each step until I had a solid, positive identification.  I went to 66X, 54X, 46X, and finally 30X with a 20mm TV Plossl.  That was my lowest solid, consistent view for that session.  I could see it from time to time with a 25mm Sirius Plossl (24X), but I could not see it with a 32mm Antares Plossl – a better 30 or 32mm Plossl should have produced it, though – at least intermittently.

Actually, before I did this with Polaris, I shifted to Mizar and got a clean split right down to 19X using the 32mm Plossl.

The Mizar connection

Why Mizar? Well, it’s nearby, so the sky conditions are pretty much the same.  The two stars, Mizar A and B are much more closely matched in brightness at magnitude 2.2 and 3.9. And finally, the split is similar to that of Polaris at 14.3 seconds vs 18.2 seconds.  While this was a piece of cake for the scope, it’s a good challenge star for the 20X80 binoculars. They do split it cleanly, but it gives me a real good idea of how close I expect Polaris B to be to Polaris A when seen in those same binoculars.

The PA of Mizar's companion is indicated by the short arrow - I think of it as always in the general direction of the 7.6 magnitude star that forms a triangle with Mizar and Alcor. Click chart for a larger version. Prepared from Starry Nights Pro screen shot.

So I split Mizar first with the 20X80 binoculars and once comfortable with that split, moved on to Polaris without changing the focus.

The numbers are precise, but the measurements aren’t

We can be such fools for numbers – see the book “Proofiness.”  But don’t let the numbers associated with binoculars fool you.  They sound precise, but they aren’t.

But first, should you even expect to be able to split Polaris with binoculars? In this case you need to forget about  the usual answer to that question which starts with checking the Dawes limit. The Dawes limit for an 80mm objective is 1.4″   ( Dawes limit = 4.56 arc seconds/Objective diameter in inches.) Ha! Good luck. As star splitters know this is seldom achieved and of course there are  many other variables – local conditions, observer, and the difference in magnitude in the two stars, for example. These all have a significant impact on the true limit of what you can split leaving you with a rough, but useful guide.  However, when you introduce binoculars into the equation all bets are off – the Dawes limit moves from being a reasonable guide to being virtually meaningless.

I like the formula the Sky and Telescope columnist Gary Seronik uses. Because binoculars are low powered instruments, he has a rule of thumb that says the practical splitting limit for a binocular is 300 divided by the power.  By that rule the 20X80 binoculars should be able to split stars separated by just 15 seconds. The Polaris pair is 18.2 seconds apart and should fit comfortably into that rule. And, of course, the Mizar pair are a little closer together than that – and a fairly easy split, which is why I say all of these numbers are just rough guidelines.

What’s more, the numbers on your astronomy equipment may simply be wrong. In fact, the more I read, the more I am convinced that the numbers most of us take on trust and use as if they were absolutes are really approximations. This is certainly the case with binoculars, as Ed Zarenski has frequently reported on Cloudy  Nights over the years.  And Seronik, in the December 2011 Sky and Telescope, pointed this out with one simple test anyone can perform. Point a flashlight into the eyepiece end of a binocular and measure the diameter of the projected circle of light – that’s your effective objective.

Rough and ready flashlight test of the 20X80 Zhummel binoculars. The bright circle of light in the inset shows the working objective diameter the system yields for my particular pair. So while the lens may be 80mm, the effective objective is something closer to 72mm. Click image for a larger view.

If the effective objective measure is off by that much, then what about magnification? I suspect it is wrong as well, not to mention field of view. In fact, it seems like every time someone put a stock binocular to the test they find that in most cases all the key numbers tend to be on the high side. Doesn’t mean there aren’t accurate ones out there – for me it just means take it all with several grains of salt.

That’s one reason why I am not suggesting we have a contest to see who can split Polaris with the least amount of power – but I do encourage you to give it a try and report your results here in the comments after this post being sure to mention exactly what you were using by make and model.  And if you’re new to this game, don’t get discouraged. A decade ago I was feeling very satisfied to split Polaris at high power with a 6-inch!

As for me, I’m going to keep trying. The “intermittent” split I got last night isn’t good enough. I could only hold it for about 10 seconds at a time. What’s more, I want to try the 25X100 Zhumells again on this, plus the 20X60 Pentax – and  I have some 16X70 Fujinons on the way. These last are, according to the reviews I’ve read, really, really good. Wonder if it will make a difference? Since you’re only using the center of the lens, I suspect the inexpensive Zhumells are pretty good – but the Fujinons may do better because of better contrast – and the individual focus eyepieces should do a better job of finding and holding the best focus.

I’ll see. Meanwhile, I expect to use Polaris as a frequent warm-up exercise for star splitting, helping me to fine tune focus, get used to the correct eye position, and telling me when I am well dark adapted – not to mention having something to say about transparency and seeing on any given night.

.

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Seeing double the natural way – looking up with both eyes and binoculars

The best way to look at the stars is to lie back in the grass on a hill side on a warm summer’s night in a region free of light pollution and look up. The only way to improve on this is to add binoculars. And when it comes to splitting doubles, this is doubly true!

Bring on the doubles! - 25X100 Zhummel binoculars.

Binoculars make a terrific double star instrument because you are doing what comes naturally – you are using both eyes and you are looking up. And there are loads of beautiful doubles that provide absolutely charming splits when viewed properly in binoculars. What’s more, binoculars give you a sense of context. Because they give a correct image and wide field of view, the transition from naked eye is not so abrupt or confusing. It’s a great way to learn your way about the night sky and to keep what you view in context.

I should add that once you get past the smaller binoculars it is neither simple, nor cheap –  it actually gets about as complicated, cumbersome, and expensive as using a telescope. Image stabilized binoculars maintain the size and portability we have come to associate with binoculars while making it easy to get a steady view, but they are expensive. However, most of the time I use larger binoculars and their mounts are  as heavy and awkward as any mount and as expensive. There’s no free lunch here – but for me the binocular astronomy experience is well worth the effort and price.

But I have a confession to make. Until very recently I didn’t consider this the case. I thought binoculars did a poor job with doubles – but I now think this was my special hurdle to leap and now that I’m over it I’m in bin ocular double star nirvana – so I decided to provide some basic guide lines for splitting doubles with binoculars, plus a short list of some especially useful binoculars doubles that range from easy to difficult and will give you a way to test yourself and your binoculars, should you care to.

My knowledge comes the hard way – I acquired it through numerous hours of observing and most of them were relatively futile. If you want to read the whole saga of my personal journey with binocular doubles, go here.  But I really think most people have a far, far easier time of it with these inexpensive and highly portable instruments. So let’s get started.

Short List of Binocular Doubles

First, here’s a list of some excellent spring and summer binocular doubles arranged in order of the easiest to the most difficult. The top of the list can be split by any binocular, the mid section takes a good astronomy binocular, such as a 10X50, and the last few call for big astronomy binoculars in the 20X80 or 25X100 range – which can now be acquired quite cheaply, incidentally, but mounting them is the rub.

  • Mizar and AlcorMany can split these two famous stars in the handle of the big Dipper with the naked eye, but for me it always takes binoculars – any binocular.  RA:  13h 24m   Dec:  +54° 56′ – Mag:   2.2, 4  – Sep:  11.8′ (708.5″)  – PA :   71°
  • Epsilon Lyra – Double Double – No, I don’t mean to actually split each star – I mean the initial split into Epsilon 1 and Epsilon 2 – that’s easy for any binocular and since these are in the same low-power binocular field as Vega, easy to find. I am able to split these with my  6.5X21 Pentax “Papilio” – the “butterfly” binoculars.  RA: 18h 44m   Dec: +39° 40′  Mag.: 5, 5.2 –  Sep. : 210″
  • Nu Draconis – The famous “Dragon’s eyes” are delightful because the split is clean with just about any binocular and the stars nearly identical. RA: 17h 32m Dec: +55°11′  Mag: 4.88, 4.86 Sep: 63.4″ PA: 311°
  • 16 & 17 Draconis – This pair is more widely separated and easier to split than Nu, but I listed it after Nu because it is a bit more difficult to find. RA: 16h 36m Dec: +52°55′  Mag: 5.4, 5.4 Sep: 90″ PA: 196°
  • Albireo – Beta Cygni – I think this has got to be one of the most popular double stars there is, and while it mark’s the Swan’s head, it is easier to find with the naked eye, than with binoculars. The reason is it’s in the heart of the Milky Way and it’s hard to know which is the star you seek because there are so many. RA: 19h 31m Dec: +27°58′ Mag: 3.4, 4.7  Sep: 34.7″ PA: 55°
  • Psi Draconis – I know I have the right star when I see the perfect little kite asterism  in my binoculars with Psi as the brightest member – RA: 17h 41.9m   Dec: +72° 09′  Mag.:   4.6, 5.6  Sep:   30.0″  PA:   16°
  • RegulusAlpha Leonis –  With a separation of nearly three minutes of arc you would think this one would be up with the other easy stars – it’s isn’t because the magnitude difference is so great – great enough for me to call ont he light grasp of an 80mm or 100 mm binocular. RA: 10:08:22.1 / Dec: +11:58:01 – Mag.: 1.35, 8.12  Sep.: 177.6  PA: 207°
  • Mizar – Yep, this is the brighter half of Mizar and Alcor and it does make a lovely split, but it takes more binocular muscle – more like 20X and easier with 25X.  RA:  13h 24m   Dec:  +54° 56′   –  Magnitudes   2.2, 3.9 – Separation  14.3″ – Position Angle    153°

Short check list of guidelines for getting the most from your binoculars

Garrett Optical 28X100 binoculars on Universal Astronomics Millenium Mount with rotating beach chair - to me the perfect chair to sit in while using binoculars since it both leans back and rotates, but hard to find and the most recent version of this chair I found was not that well made.

From my experience I’ve developed some basic guidelines for splitting doubles with binoculars.   Many of them you probably already do. If so, treat this as a reminder.

  1. Wear your glasses if you have astigmatism – otherwise do without.  And if you need glasses, seek binoculars with long eye relief and flexible eye cups that roll back.  You only need to see the center of the field to split a double, but the whole field is useful for finding the double.
  2. Sit down – or better, lie back in a lawn chair – you must be comfortable. Get in a position where you are looking at your target area without strain, then bring the binoculars to your eyes. This is important. Even with a nice Parallelogram mount I frequently see people raising their head and straining their necks to look through binoculars. Take the time to make the mount do the work for you.
  3. Hold the binoculars steady – even 7X50s will benefit from being on a tripod, or parallelogram mount unless, of course, they are the image stabilized types. Most people think they can hold binoculars steady. Wrong! And this is doubly wrong if you’re trying to split close doubles. An ordinary photo tripod can hold small and medium binoculars, but will likely result in a pain in the neck. I can’t use one for anything except objects that are so low the atmosphere becomes a problem. However, I know excellent observers who use such amount for all their  binocular observing. I much prefer the kind of parallelogram mount that puts the binoculars to one side of the tripod or pier so you can observe comfortably while seated in a lounge chair. This isn’t laziness – it’s practical considerations related to seeing well.
  4. Focus carefully – very carefully – with center focus types remember to focus first the left eye with the right closed, then do the diopter adjustment for the right eye while keeping the left eye closed. I know everyone should know this already, but it’s surprising how many people have used binoculars casually for years without being aware of it.  Acceptable focus for land views just isn’t the same as the critical focus needed to split close doubles. Once you have the diopter set, you can leave it alone and just use center focus.
  5. Get the interpupilary distance right!  That is, make sure the binoculars are the same distance apart as your eye. This is another one of those things that might evoke a duh! But the truth is, your brain wants to see a single image and might be working overtime to give you one because the binoculars aren’t adjusted properly for your eye. (This is also true if your binoculars are out of collimation – but evaluating and correcting collimation is a topic beyond the scope of this post.)
  6. Spend time on target – Look for at least one solid minute – don’t expect instant success. Don’t fiddle with the focus forever – give your eyes time to adjust. This is one of the key instructions in Crossan and Tiron’s “Binocular Astronomy.” They write:”the most important thing in observing is to really look – a mere glance at an object or a field is simply not enough. You must keep your eyes at the oculars for a full minute at a time.” I can’t stress this enough. over and over again I see people taking mere glances and thinking they have seen all that can be seen. As Holmes told Watson: “You see, but you do not observe.”
  7. Relax your eyes – let them focus at a distance and get used to it. I wish I could explain this better. I feel it’s important, but I’m not sure exactly how to describe it. If I’m in doubt I take down the binoculars and just try to let my eyes focus on the stars. Then I come back to the binocular view.
  8. And if all this fails to deliver sharp star images, maybe you have a problem similar to mine – back off from the eyepieces an inch or two, move your head about some – find the correct head position – the one that works and yields sharp stars.

This last has driven me crazy and continues to puzzle because believe me.  Points one through seven didn’t make a difference for me until I could settle the issue of point 8 and right now I’m not sure how many others have a similar problem, but I think it’s relatively few.

I’ve been to both the eye doctor and my massage therapist and right now the one whose advice makes the most sense relative to this situation is my massage therapist. She noticed me holding my head a bit funny and she knew I had flexibility problems with my shoulder and neck. These apparently don’t come into play when I am leaning over the eyepiece in the diagonal of  a refractor or catadioptic telescope – or for that matter, looking directly into the eyepiece of a reflector. But when I look up to look through binoculars, all bets are off. What feels natural to me simply isn’t the position that yields sharp star images. For years I have blamed this on the quality of the binoculars. Then for a while I blamed it on what I perceived as my astigmatism. But tests show that astigmatism is slight and what I am finding is critical is getting my head into a position that works – even if it feels unnatural to do so.

I discovered this by backing away from the eyepieces as much as two or three inches and moving my head around, tilting it in various angles.

My advice to you? Don’t worry about this unless you’ve tried everything else and are still having problems getting sharp star images.

Meanwhile, check out some of the doubles on the short list. Warm up by trying the easiest first – and get your focus right on them. Most are conveniently grouped with other bright stars and easy to track down – and each is distinctive. Even if you have seen them all in telescopes, the binocular view is different and special. Give it a try and see if you don’t agree.

More binocular astronomy resources:

Binocular  Highlights” by Gary Seronik – this is a great book to begin with. It mentions several double stars, but a lot of other good objects to look for with your binoculars. Also, scroll down his web site for some excellent binocular reviews and related suggestions on mounts.

Review of Binocular Mounts – Go here to learn of  some of the possibilities of commercial binocular mounts. If you’re handy with tools, there are plans here for making a parallelogram mount.

Binocular Astronomy, Crossen and TironAgain, a good guide. I have the first edition – have not seen the newer one advertised here, but I assume it is at least as good.  This is a general guide with lots of solid observing advice and several specific doubles.

Binocular Double Star  Club – Here’s a good list to whet your appetite – and if you’re into “awards,” go for it.

Zeta (ζ) Geminorum — Another Neat Knee Star

So there I was, trying to enhance my dark-adapted vision by sitting in the dim light of dusk with no lights on in the house, leaning forward in my chair, shoulders hunched over that old and dependable 1844 standby, The Bedford Catalog,  skimming the table of contents for the entry on Epsilon (ε) Geminorum  . . . . . . .  when suddenly my eyes landed on Zeta (ζ) — which came as a complete shock.

Not sixty seconds prior to that I had been looking at Gemini in The Cambridge Double Star Atlas, and had noticed Zeta (ζ) was devoid of a double star designation.  Haas doesn’t mention it all, and you have to look closely in Sky & Telescope’s Pocket Atlas to catch it’s double star status because it’s also identified as a variable star (a Cepheid) . . . . . .  which we’ll circle back to shortly.

Now I’ve never quite figured out why one atlas will identify a specific star as a double, and another will ignore it, especially when the star is as obvious and easy as this one is — but, as Galileo tried to tell the Pope, “It is what it is.”   On the other hand, there are so many double and multiple stars scattered about the galaxy, no one person or atlas can track all of them — although I’m doing my best to get there first.  😉

At any rate, my imaginative attention was completely captured by the fact that Zeta (ζ) is  also a “knee-star” — meaning it’s located on Pollux‘s right (west) knee, opposite its Castorian counterpart, the very attractive Epsilon (ε), shining richly in yellow from Castor‘s right knee.  Kind of “kneat.”

But that led to another thing that caught my attention — which is how the dual knee stars match up well with what I’ve always thought was an uncanny symmetry about Gemini.  Granted, we’re dealing with twins here, but the two sides of Gemini — the Castor side, and the Pollux side — are so darn close to being mirror images of each other, it’s really stretches the boundaries of belief.  And here we have it again, with each of them sporting double stars on their knees.  Rather dazzling of them to dress that way, too.

And then there was one more thing that caught my attention — which is the number of components in Zeta (ζ).  There are a total of five, ranging in magnitudes of 4.1 to 13.5, all widely separated, and thereby eliminating any question of obscuration by omnivorous photons.  Although it did occur to me that the dim 13.5 magnitude “E” beacon-ette could well prove to be a challenge.

At any rate, now that you’ve been introduced to Zeta (ζ), let’s go find it and see what it has to offer.

Zeta (ζ) Geminorum     (Mekbuda)  (H VI 9) (SHJ 77)  HIP: 34088   SAO: 79031
RA: 07h 04.1m   Dec: +20° 43′
*****                      Magnitudes         Separation        Position Angle         WDS Data
SHJ 77       AB        4.1, 10.7                 87.3″                       85°                         1997
SHJ 77       AC        4.1,   7.7               101.3″                     347°                        2008
SHJ 77       AD        4.1, 12.6                 67.8″                     354°                        2008
TOB 46      CE        7.7, 13.5                 97.1″                     322°                         1997
Distance: 1169 Light Years
Spectral Classifications:  “A” varies from F7 to G3, “C” is classed as G0

Since the illustrious and industrious Admiral Smyth is the one responsible for our being here to start with, let’s see what he has to say:

A coarse triple star, on the right knee of Pollux.  “A” 4, pale topaz; “B” 8, violet; and “C” 13 Grey.  . . .  It is easily seen on running a line between the cluster in Orion’s sword and Pollux, for it passes over ζ at 9° from the latter star; and it is near the mid-distance between ζ Tauri, the tip of the southern horn, and the Præsepe in Cancer.”

(The Bedford Catalog: Willman-Bell, 1986: p. 169)

I’ve labeled M 42 (“the cluster in Orion’s sword”), Zeta (ζ) Tauri, and M 44 (“the Præsepe, or Beehive Cluster”) in yellow on the chart above, so if you follow either of the Admiral’s directions, you can’t miss. And, if nothing else, you can always leap southeast from Castor’s yellow knee to get to Pollux’s yellow knee. (Stellarium image with labels added, click to enlarge)

Let’s start with the Admiral’s lettered designations first, since it seems the identities of two of the stars have been reversed.  The one he refers to as the eighth magnitude “B” star is now the 7.7 magnitude “C” component, and the 13th magnitude star he refers to as “C” is now identified now as 10.7 magnitude “B”.  And as for his colors — well, we’ll go take a look and see for ourselves in just a minute.

The 76mm Tasco surveying the darkness.

Now the last time out, I invoked the aid of Homer, that great 700 B.C. Bard of  Greece, in hopes of breaking the weather curse cast upon me by the cloud creating Sky Gods.  And, bless his ancient heart, he heard my desperate plea and succeeded in scattering the snickering omnipotent ones for long enough that I had one good night.

So with clear skies and very few clouds in sight, but banished from my second floor observing deck by a thin layer of ice that should have been on top of a skating rink, I grabbed an old 76mm Tasco f/15.8 refractor and headed for my gravel driveway, where the surface was richer in friction.  I plopped an old Vixen Polaris mount down in the drive, attached the scope, let it cool while I found some warmer clothes, and then re-emerged into the balmy thirty-five degree second-day-of-Spring-air, and aimed the Tasco at Zeta (ζ) per the Admiral’s directions.

“A coarse triple star, on the right knee of Pollux.”  Click to lose this caption, and to get the best effect, turn out the lights!  (East & west reversed to match the refractor view)

What I found looking back at me at 60x was a pale, yellow-white primary shadowed by an obvious companion to the north — and after roving around the east edge, I spied a third star with averted vision.  I recognized it immediately.  There was no doubt in my mind that was the star the Admiral described as “grey” — it was as if I had seen it before.  Thirteenth magnitude it is not (the current 10.7 is a better match), but at the time the Admiral made his observation, magnitudes were consistently under-estimated in comparison to today’s numbers.   It’s a tricky little devil in a 76mm scope, but a bit of magnification (80x) brought it out of it’s aversion to my vision with reasonable distinction.

Getting back to the color of the primary, if the Admiral’s “topaz” refers to yellow-white, that would correspond pretty well with what I saw — it certainly wasn’t the eye-catching deep yellow I saw glowing in that other “knee star” to its west, Epsilon (ε).    Sirs James South and John Herschel scrutinized Zeta (ζ) on March 24th, 1821, and described it as “large yellow; small ash color.”  And Sir William Herschel, who discovered this one on October 7th, 1779, described it as “Double. Very unequal. L. reddish w[hite].; S. dusky r[ed].”

As I mentioned in the first paragraph, Zeta (the primary) is a Cepheid variable, which has a bearing on its color.  Kaler states that its magnitude fluctuates every 10.2 days, between 3.7 and 4.2, and its surface temperature ranges from 5300 to 5800 Kelvin (making it a close match to the 5777 Kelvin of our sun) — and that causes its spectral classification to vary from F7 to G3.  All of which keeps its apparent color in the yellow-white range.

So yellow-white seems to be the majority opinion on the primary, and I’ll gladly agree with the Admiral on “grey” as a good description of 10.7 magnitude “B” — but we’re all over the galaxy on 7.7 magnitude “C”.  The Admiral says violet, James South and John Herschel went with ash, and Sir William saw “dusky r.[ed].”  I saw pale blue-white — yet it’s stellar classification, G0, says it should be yellow-white.   So take your pick, or better yet, take a look.

Now when I took my look, I was also looking hard for some sign of 12.6 magnitude “D” and 13.5 magnitude “E.”  I really didn’t expect to see those in the 76mm Tasco, but having familiarized myself with the photonic framework of Zeta (ζ), I attacked again the following night with my five inch f/15 refractor  — and found myself subjected to the revenge of the Sky Gods.  They conjured up a dry and strong east wind — always a guarantee around here of atrocious seeing — and then one of those chuckling characters began slowly pulling a blanket over the sky, from south to north.  I could swear I heard a sinister giggle or two as the clouds advanced, but maybe it was just the wind.

Anyway, I managed a glimpse of Zeta (ζ) at 64x and 95x, but the leading edge of the clouds had advanced so far I could barely catch an averted glimpse of 10.7 magnitude “B” — heck, I had a better view the night before in the 76mm Tasco!  If I thought it would help, I would gladly sacrifice another eyepiece to those over-bearing rulers of the sky, but I’ve already done that so many times they have more hardware now than I do.  So I guess I’ll holler for Homer again.

But to avoid delaying this for three months while I wait for the Sky Gods to go torment some other poor soul, I’ll post what I have now.  With any decent change in luck, accompanied by a decent change in the weather, I’ll zero in on Zeta (ζ) with a five or six inch refractor and see if I can ferret either, or both, of those two fainter companions, “D” and “E”, out of the depths of interstellar space.  I see nothing but rain and clouds in the forecast for the next week, and then the waxing moon is going to be too close to Gemini for me to see down to 13th magnitude, so it looks like a delay of at least several weeks.

I suspect that because “D” is wedged about halfway between the primary and “C”, it might be a real challenge to pick it out of the glow.  On the other hand, even though “E” is almost a magnitude dimmer, it’s northwest of “C” and far enough away from all of that starlight that it could well prove to be the easier of the two.  In the meantime, if anyone out there catches a glimpse of either the “D” or the “E” component — or both (!) — post a comment here.  If you have a sketch, I’ll be glad to add it here as well.

Oh — and before I forget — Mekbuda is an Arabic name for “folded paw,” referring to that of a lion.  Once upon a time this area of the sky was home to a lion who has since migrated elsewhere, possibly into Leo’s domain.  At any rate, he’s moved on and the Gemini twins have staked a claim to this sector of the sky, yellow knees and all.

Meanwhile, to the folks at asociacionhubble.org  —  Saludos!
. . . .  and to those at astronomy.ro  —  Salutări!   😎

The Tasco family on a warmer night. The 76mm is on the left, the 60mm on the right. Click for a larger view.

In the Realm of the Ophiuchan Triangle: 61, 67, and 70 Ophiuchi; and S 694

When you have a chance to catch a clear, dark, moonless evening in August, take a glance up into the southern sky at the brilliant blue and white beauty of first magnitude Altair.  Then follow the trail of the Milky Way southwest from it to the first, rather large, glowing cloud of stars you come to — which is known as the Scutum Star Cloud.  Make a fist with your right hand, hold it up to the right (west) of the cloud and turn it so it’s at a ninety degree angle to the line that runs back to Altair.  And — unless you have a HUGE hand — at the right edge of it you’ll see a distinctive triangle of stars formerly known as Poniatowski’ Bull.

Mark that location in your memory, go grab a telescope, and follow me  ……..  ’cause that’s where we’re going tonight.

The Scutum (SKOO-tum) Star Cloud is seen here glowing about twenty degrees southwest of Altair. A twenty degree hop to the northwest from the Cloud will land you in a triangle consisting of 70, 67,and 68 Ophiuchi. All three of these are multiple stars, but 68 (Bu 1125), a triple, is a bit beyond our reach with separations of .4″ and .5″. This Ophiuchan triangle doesn’t have the same sinister reputation that the more famous Bermuda triangle does, but it might still be a good idea to follow my directions closely to avoid slipping into oblivion in Ophiuchus. (Stellarium screen image with labels added, click for a larger view)

There are a group of stars which have become famous for their seeming ability to display a wide range of colors.  One of the better known is 95 Herculis, made famous in particular by Admiral William H. Smyth’s observation of “light apple green, cherry red” in 1857. Others on that list include Delta Herculis, Gamma Delphini, and Gamma Leonis, which is better known as Algieba.

There’s one more, though — and it goes by the name of 70 Ophiuchi.  Just by chance, that happens to be our first stop.

The three stars that form our triangle — 70, 67, and 68 Ophiuchi — were once part of a constellation known as Poniatowski’s Bull, which has since been relegated to “asterism” status. Also visible on this chart is the fast moving ninth magnitude Barnard’s Star, six light year distant from us, moving at the rate of 10.4 arcseconds each year.  (Stellarium screen image with labels added, click to enlarge)

Splitting Tools: And for binary binocular fans, two of the stars shown on the chart above and described below — 67 Ophiuchus (the AC pair) and S 694 — are easily split in mounted 15×70 binoculars — and provide great views in either a 50mm or 60mm scope as well.

70 Ophiuchi  (Σ 2272)  (H II 4 — AB only)           HIP: 88601    SAO: 123107
RA: 18h 05.5m   Dec: +02° 30′
Magnitudes   AB: 4.2, 6.2     AC: 4.2, 12.0    AV: 4.2, 10.8
Separations  AB: 3.4″           AC: 34.9″          AV: 143.9″
Position Angles  AB:  79° (WDS 2012)    AC: 282°  (WDS 1947)   AV: 275°  (WDS 2010)
Distance: 16.6 Light Years
Spectral Classifications  A: K0   B: K4

So what color are they, really?   If you go by the spectral classifications, “A” and “B” should be orange.  Sir William Herschel, who discovered this pair in 1779, apparently didn’t notice anything distinctive here since he didn’t leave us a comment on their colors.   Admiral Smyth saw “pale topaz and violet,” and Haas describes them as two “tangerine-orange” stars.  Others have seen yellow and gold, and Flammarion even described “B” as “rose-colored.”  In his chapter on Ophiuchus, Burnham writes that he always saw them as “golden and rusty-orange.”

Orange or gold? Topaz or violet? Maybe even rose colored? I saw various blends of orange and gold in several different scopes. (East & west reversed to match the refractor view, click to enlarge)

In my 60mm f/16.7 refractor, using a 20mm TV Plössl (50x), I saw a gold primary with a touch of orange in it, and the secondary was a pale version of the same thing.  Three weeks later, using a 102mm Celestron refractor and a 24mm Brandon (42x), I saw orange and orange.  But in my six inch f10 at low magnification, the gold won out over the orange.

So with a fair degree of certainty, I think you can more than likely, somewhat definitively, and even reasonably safely, say  ………..  either gold and/or orange. 😉

Whatever the colors, I’m sure you’ll notice this is a rather tight pair of stars.  I haven’t quite made up my mind yet whether I like the low power view which has them so close they’re barely apart, or the high powered view that includes a wedge of black sky between the two stars.  There’s a lot to be said for the delicate nature of the low power view, with that diminutive little secondary clinging to the edge of the brighter primary, illuminating the inside of your eyepiece with their gold or orange photons.  I do know they’re a great pair for a 60mm scope — just close enough together at 3.4 seconds of arc, and far enough apart in magnitude, to be a little bit of a challenge.  And the reward is well worth the small effort it takes to separate them.

Regardless of how or when you view them, I’ve found their most striking aspect (apart from the colors) is the way the two stars dominate the field of view.  In the 60mm refractor at 50x, “A” and “B” are just two orange/gold points of light shining at the center of a black void. They don’t have any competition at all in that dim field, which is probably fortunate, since there are only a handful of stars in the sky that can compete with them anyway.

At a mere distance of 16.6 light years, this pair is one of our nearest neighbors.  It’s also a fast orbiting twosome, with a period of 88.4 years — fast enough that a person could watch their positions gradually change over the course of a long life.  During that time, their elliptical orbit brings them as close as two arcseconds and as far apart as seven arcseconds.  Admiral Smyth’s Bedford Catalog has a very interesting discussion of 70 Ophiuchi (pp. 404 to 409), including tables showing their rapidly changing positions between 1799 and the early 1840’s.

And it appears this is a very complicated system.  The Washington Double Star Catalog shows a total of eleven  stars involved.  Quite a few of those eleven companions are in the 14th to 16th magnitude range, well beyond the reach of most of us.  I’ve included just two in the data shown above, “C” and “V,” but so far “V” is the only one I’ve managed to pry out of the inky darkness.  Because of the glare from the primary and secondary, that took some rather hard staring in the 60mm refractor using an 11mm TV Plössl (91x).  Larger apertures failed to find “C” hiding in its closer location to the primary.  Still, how many times can you lay claim to having seen the “V” component of a multiple star?  And in a 60mm scope even!!!

Now let’s move from the northeast corner of this triangle and over to the northwest side, a hop of a short degree or so, where 67 Ophiuchi lies waiting for us.

67 Ophiuchi  (Bu 1124)  (H VI 2)            HIP: 88192    SAO: 123013
RA: 18h 00.6m   Dec: +02° 56′
*****                  Magnitudes   Separation  Position Angle   WDS Data
AB: (Bu 1124)    4.0, 13.7             6.6″                196°                 1934
AC:  (H VI 2)       4.0,   8.1           55.9″                139°                 2009
AE: (Bu 634)      4.0, 11.0           45.7″                179°                 2002
CD:      ”               8.1, 12.5             7.7″                123°                 2002
CE:      ”               8.1, 11.0           33.2″                266°                 2002
Distance: 1418 Light Years
Spectral Classifications     A: B5   C: B2

“A” and “C,” the two stars you’ll see immediately when our goal glides into view in your eyepiece, were discovered by Sir William Herschel in 1779.  S.W. Burnham came on the scene in the 1870’s, and ferreted AB, AE, CD, and CE from the darkness, which gained his designations shown above, Bu 1124 and Bu 634.   Beyond any doubt, though, the main attraction is the pair discovered by Sir William.

60mm, 25x: Grand sight!  A bright lemon-yellow star with a little silvery dot beside it.  The pair looks about as wide as Albireo. Webb: ‘Yellowish, blue.’  Smyth: ‘Straw color; purple.’ ”  (Sissy Haas, Double Stars for Small Telescopes, p. 112 of 2006 edition)

You can always depend on Admiral Smyth to find some purple in a star, but he deserves some recognition for coming up with “straw colored.”  I didn’t see it, though.  What I did see in my 102mm Celestron f/10 was a bright white primary and a pale blue secondary.

67 Ophiuchi is woven into a very interesting field of 9th and 10th magnitude stars. Included here is the elusive eleventh magnitude “E” companion. (East & west reversed, click for a larger view)

But Sissy Haas’s “grand sight” in a 60mm scope is quite correct.  At 55.9″ apart, splitting the pair is no issue, although seeing the 8.1 magnitude “C” star can be a bit of a battle if the moon has been turned on and is flooding your skies with its surplus of reflected light.  I had to fall back on averted vision to avoid failure the first night I looked for it, but once the moon was out of the skies, its “silvery” personality popped into view.  Silver, or maybe gray, is what I saw in the 60mm f/15 mounted on the 102mm Celestron, since the sixty millimeter lens just couldn’t collect quite enough light to display any color.

I was determined to see one of S. W. Burnham’s stars, though, and again, the moon made it difficult.  After having no luck with my six inch f/10 just as the moon was rising, I decided to give an eight inch Celestron SCT a try the next night.  I had to be quick, though, since a last quarter moon was due on the horizon at 10:30 PM, about an hour after darkness set in.  “B” was out of the question because it’s faint 13.7 magnitudes of dim light would be lost in the glow of the fourth magnitude primary.  And 12.5 magnitude “D” was excluded because the 7.7″ separating it from “C” would also put it behind the glow caused by the 4.4 magnitudes of difference between the two stars.  So that left “E,” at a magnitude of 11.0, sitting 45.7″ from “A” and 33.2″ from “E.”

And sure enough, even though it took about twenty minutes before I spied it, that’s where it was — sitting between “A” and “C,” forming a very tight triangle with an eerie resemblance to the larger one formed by 70, 67, and 68 Ophiuchi.  It took a 15mm TV Plössl (133x) to find it, and even then it wanted to play hide and seek behind the glow of its brighter companions.  But it was soon gone again, receding into the much brighter glow of the sky as the moon began its climb into the northeastern sky.

And since it’s gone, we’ll go on.

A three degree hop to the west from 67 Ophiuchi will get us to 3.8 magnitude Gamma (γ) Ophiuchi, and another three quarters of a degree will bring us to our next star, 61 Ophiuchi. (Stellarium screen image with labels added, click for a larger view)

61 Ophiuchi  (Σ 2202)  (H IV 32 — AB only)          HIP: 86831    SAO: 122690
RA: 17h 44.6m   Dec: +02° 35′
Magnitudes    AB: 6.1, 6.5       BC: 6.5, 12.8
Separations:  AB: 20.6″           BC: 93.6″
Position Angles:  AB: 93°  (WDS 2010)         BC: 28°  (WDS 2005)
Distance: 460 Light Years
Spectral Classification: A1 (for “A”)

This time, we’ll turn the floor over to the Admiral:

A neat double star below β, on the Serpent-bearer’s left shoulder, where it is 2° south of the bright star β, Cebalrai, which lies about 7° south-by-east of α Ophiuchi.  A and B, both 7 ½, and both silvery white.”  (The Bedford Catalog, Willman-Bell: 1986, p. 396)

“A neat double star below β, on the Serpent-bearer’s left shoulder . . .” (East & west reversed again, click for a larger version)

Haas describes them as “straw-yellow” in a 60mm refractor at 25x, and what I saw in my five inch Meade was two pale white stars with a slight  tinge of yellow in them.  It’s not often that the three of us agree that closely on color!

After the proliferation of components listed for our two previous stars, 61 Ophiuchi is relatively unconfusing.  But that 12.8 magnitude “C” companion was lurking in the blackness of interstellar space, and I just couldn’t resist giving it a try.  Actually, after searching for the fainter companions of 70 and 67 Ophiuchi, this one wasn’t much of a struggle in the AR5.  The wide gap between it and the primary, over one and a half arcminutes, put it beyond the reach of the glow surrounding it’s two much brighter relatives.  Although it wanted to play hide-and-seek at first, with some persistence I could see it with direct vision for a few seconds at a time.

Interestingly enough, the primary and secondary have shown little motion over the years.  Smyth includes a table of observations made in 1834 by the Reverend R. Sheepshanks (and no, I did not make up that name!) showing a position angle of 93° 37′ and a separation of 20.75″, which measures up well against the WDS’s 93 degrees and 20.7″.

And now I hear James South calling to us, so let’s go see what he has up his sleeve.

S 694            HIP: 87448    SAO: 122847
RA: 17h 52.1m   Dec: +01° 07′
Magnitudes: 6.7, 7.3
Separation:  79.0″
Position Angle: 237°  (WDS 2003)
Distance: 465 Light Years
Spectral Classifications: K0, A0

To get where we’re going, we’ll use the chart above and move two degrees to the southeast — past 6.4 magnitude HIP 87224 and 5.9 magnitude HIP 87491 — and we’ll find Mr. South’s S 694 waiting patiently for us about a quarter of a degree to the southwest.

This one is simplicity itself — an old fashioned two star system far enough apart to easily be seen in a 60mm refractor at low magnification.   And after punishing my photonic receptors with searches for dim specks of light at or just beyond the limit of visibility, the change was more than welcome.

And this time, I’ll quote myself:

An old-fashioned two star system, but with a chameleon-like character to its color. (East and west reversed, click for a better view)

Bright pair in six inch f/10 with 12mm Radian (127x) — “A” is yellow white, “B” pale white.

Easy pair in 60mm f/15 with a 20mm TV Plössl (45x), HIP 87491 seen in the same field of view.”

August 1st, 2300 PDT, 2011.

Ah, but those colors again.  They’re up to their old tricks.

Haas used a 125mm scope at 50x, and she saw “pumpkin orange and the other greenish white.”  She quotes Rachal as having seen “yellowish orange, bluish white” in a 70mm.

So we’re back to a familiar question: What color are they, really?  With a spectral class of K, the same as 70 Ophiuchi, the primary should appear to be orange — but I sure didn’t see it, and I looked at it with several different scopes.  And the secondary is classified as A, which means it should appear as either white, or the bluish-white that Rachal observed.  But all three of us picked up some shade of white, so that makes the primary the primary offender.

What to do, what to do, what to do  …………….   I was tempted to ask the good Admiral, but I could clearly hear him reply:  “Lilac.”

What I did  do was go back and take another careful look at this pair, using my Celestron six inch refractor.  And darned if I didn’t see gold with a tint of orange in the primary, and just a hint of blue in the mainly white secondary.  In fact, at low magnifications, you can pull the well-behaved HIP 87491 into the field of view.  It’s a deeper orangish-gold color, which agrees well with it’s K5 classification, and it provides a wonderful contrast with the weaker orange-gold I saw in S 694’s primary.

So I’ll leave you to puzzle this one out for yourself — take a look and see what you can see.  Meanwhile, I think I’ll wander up north of Cebalrai and take a look at the well-scattered beauty of IC 4665, and them I might meander over to Poniatowski’s bull and hitch a ride through the southern reaches of the zodiac.

Clear Skies!

The Omega (ω) and the Omicron (ο) of Cygnus: ο-1 and ο-2; and ω-1 and ω-2 (S 755 and S 756)

Confused by the title?

Well, it’s no wonder.  Appearances just aren’t what they seem in Cygnus.

The Omega (ω) and Omicron (ο) of Cygnus, tucked into its northwest corner. (Stellarium screen image with labels added, click to enlarge)

There are rumors of some very strange things happening up in that sector of sky.  One Greek letter subdivides in the night, followed by another, and then one of those halfs halves itself again  ………………..

……………….   and the result is rampant confusion on a stellar scale.

But have no fear.  Any Star Splitter worth his eyepieces and focus fingers should be willing to accept the challenge of making order out of this disorder.

So here I am.  😎

But I have to confess, every time I’ve looked at this section of the sky, I’ve been unable to  make heads or tails out of it — not to mention AB, AC, or AD.  What little information I had was very nebulous and no help.  I couldn’t tell Omicron-1 from Omicron-2, and the Omega pair puzzled me at least as much.  Without a scorecard, I was lost in space — and  I suspect Sissy Haas had a similar experience since she leaves both Omicron (ο) and Omega (ω) out of her listings.

So  —- we’ll start with Omicron-1, and for a taste of the astronomical confusion surrounding it, take a look at Jim Kaler’s first paragraph on  it.

You’ll find Omicron-1 and -2 located halfway between Deneb and Delta (δ) Cygni and slightly to the north. Omicron-2 forms a low and wide triangle with Deneb and Delta (δ), which may be a better way to locate it, depending on your sky brightness. I had no trouble seeing both of them with the unaided eye while the moon was ninety percent of the way to being full. There’s a more detailed chart further down the page. (Stellarium screen image, labels added, click to enlarge)

Splitting Tools for Omicron-1 and Omicron-2: The “C” and “D” components of Omicron-1 are a breeze in a 50mm or 60mm scope as well as in hand-held or mounted binoculars, and are stunning sights — see Greg’s comments at the end of this post for some of the details.  Both components of Omicron-2 are also easily seen in 50mm and 60mm scopes —  although visible in a pair of mounted binoculars as well, they lack the visual appeal of Omicron-1.  The first three sketches below were all made with a 50mm scope!

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
AB:         3.9, 13.4            36.0″                327°                2007
AC:         3.9,   7.0          106.7″                174°               2008
AD:         3.9,   4.8          333.8″                325°               2008
Distances:  “A” is at 1354 Light Years; “D” (30 Cygni) is at 717 Light Years
Spectral Classifications: All K2

As the Washington Double Star Catalog (WDS) numbers above would seem to reveal, Omicron-1 is a quadruple star.  But “B” — which at a magnitude of 13.4 you can count yourself fortunate to see — is listed with a separate designation, HJ 1495 (h 1495 in Sir John Herschel‘s catalog).  And “D,” at a distant five and a half arc minutes away — and also designated as 30 Cygni — does not, per Jim Kaler’s comments above, seem to be part of this system.  And that becomes obvious when you take note of the 636 light years separating 30 Cygni from the numerously-named primary.

Ah, but the real question, the one that draws us here in the first place, is what does Omicron-1 look like in a telescope.

It’s stunning.

The stunning gold of o-1 and the white white of 30 Cygni (“D”). (East and west reversed to match the refractor view, click for a view without this caption.)

The primary is a deep gold, with even a touch of reddish-orange flickering to life every now and then.  “B” is invisible — no surprise there — and “C”, despite its dimness relative to the the rest of the system, is distinctly bluish-white.  And “D”, aka 30 Cygni, is a rather pure shade of white.  All this in a 50mm scope, no less.  And in larger apertures, the colors are much richer and vivaciously vibrant.  Did I say stunning?

And keep in mind I was looking at them on a summer evening when the moon was about eighty percent full. On a dark night?  My photonic receptors quiver in anticipation at the thought.

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: 1109 Light Years
Spectral Classification: K3, B3

Now Omicron-2 is a much simpler case, being a regular old dual pair of orbiting suns, and with only one additional designation, S 743, bestowed on it by James South.  If we had started here, though, we would have probably made things worse by working in reverse.  But we better look at this one quickly before someone adds another name to it, or it subdivides itself.

If you ban 30 Cygni from the view, the resemblance between o-1 and o-2 is downright uncanny. (East & west reversed, click to enlarge)

I had to blink a couple of times and shake my head just a bit to clear the moon beams out of my eyes.  That 80% of full moon was peering over my right shoulder when I was looking at the Omicron (ο) twins, but it was the color of the o-2 primary that caused me to blink.  Darned if it wasn’t virtually identical to the Omicron-1 primary.  Nor does the resemblance end there.  I could see the same bluish-white in the 8.4 magnitude secondary that I saw in Omicron-1’s “C” companion  ……  and the the position angles of the two stars — 174 degrees for Omicron-1 “C” and 177 degrees for Omicron-2 “B” — are so close you can’t see any visual difference.  Throw 30 Cygni out of the picture (go away, stray star!) and Omicron-1 and -2 come very close to being identical twins.

BUT —  if you really  want to feel the full impact of their virtual twin-ness, slip a low power, wide angle eyepiece into your scope, and catch both Omicron-1 and -2 in the same field of view together.

The virtual twin-ness of o-1 (at the left) and o-2 (at the right) in the same field of view. (East & west reversed, click for a view without this caption.)

Your star starved eyes will immediately be struck by those matching primary colors, as well as the echoing positions of the two stars to their south.  It really is  very striking.

And now, on to the Omega (ω) brothers — and this time we’ll run in reverse and save the confusion for last.

You’ll find the Omega (ω) twins two degrees to the northeast of Omicron-2, which will show up nicely in a 6×30 or 8×50 finder. If you don’t have a finder, move north one degree and then east two degrees to get there. These are astronomical directions, not compass directions! (Stellarium screen image, labels added, click for a larger view)

(See this post if I confused you with the comment above about astronomical directions).

Omega-2 (ω-2):
S 755  (H IV 23 — AB only)        HIP: 101206    SAO: 49731
RA: 20h 30.5m   Dec: +49° 12.5′
Magnitudes    AB: 6.6, 9.7     AC: 6.6, 13.5
Separation     AB: 59.3″         AC: 20.4″
Position Angles   AB: 278°  (WDS 2002)   AC: 118°   (WDS 2000)
Distance: 463 Light Years
Spectral Classification: A2

S 756  (Ruchba)        HIP: 101243    SAO: 49741
RA: 20h 31.2m   Dec: +49° 13.1′
Magnitudes: 5.6, 10.2
Separation: 60.7″
Position Angle: 327°   (WDS 2010)
Distance: 404 Light Years
Spectral Classification: M2

Omega-2 actually consists of what are apparently two different systems, each designated separately, one of which is a triple, and the other a double.  But at a difference in distance of 59 light years, it would be a slight stretch to call them related.

The South siblings sit at the center of the field while Omega-1 imitates inconspicuousness over in the south corner of the view. (East and west reversed once more to match the refractor view, click for a view without this caption)

On the other hand, there’s nothing difficult about this pair of multiple stars.  They leap right out at you from the eyepiece because they’re so close together.  And their tenth magnitude companions are obvious — at least in four or more inches of aperture.  I needed averted vision to see either of them in the 50mm Zeiss, but the moon had raised its wattage to about ninety percent of full on this particular night — otherwise I suspect they would have been obvious even at that aperture.

In the four inch scope, both primaries seemed to be floating above the black background.  S 755’s primary beamed back at me in pale white, and S 756’s beamed even brighter in a light gold color, flashing an occasional few photons of orange and red.  The 9.7 and 10.2 magnitude secondaries were faint — too faint for detecting color — but obvious with direct vision.  I had tried to pry those colors loose with a 6mm Radian in the AT-111 (130x), and even though that didn’t work, I did find that I could pick out two very faint stars hovering around S 756’s primary.  One was at about 280 degrees and the other was about 70 degrees, which meant they were bracketing the 10.2 magnitude secondary (both are shown in the sketch).  Apparently they’re not companions, since they’re not listed in the WDS database, but they certainly had that appearance.

And, even as I hesitate to add to the mix of characteristic confusion, it must be said, that S 756 is the star that officially carries the ω-2 designation.  S 755 must be there to keep an eye on it.

Now, as for the first Omega (ω)   ……………………..

Omega-1 (ω-1)  (Bu 669) (45 Cygni)       HIP: 101138    SAO: 49712
RA: 20h 30.1m   Dec: +48° 57′
Magnitudes    AB: 5.0, 12.9       AC: 5.0, 9.4
Separations   AB: 17.3″             AC: 55.9″
Position Angles:   AB: 336°      AC: 88°         (WDS 2000)
Distance: 870 Light Years
Spectral Classification: B2.5

……………..    I couldn’t find it.  You can see it in the sketch above, but I didn’t realize that was it for one simple reason:  I couldn’t see the 9.4 magnitude “C” companion!

I looked several times — it wasn’t there.

I went back to the Cambridge Double Star Atlas  more times than I can count, got my bearings relative to 43 Cygni and the South siblings, and looked again and again and again.  I couldn’t see anything that came close to the 5.0 magnitude of the primary — other than what turned out to be the correct star — and I kept ignoring it because of the absence of a visible companion.

Finally I realized it had to be the one, put the 6mm Radian (130x) back in the scope, looked again, and glimpsed the devious little disappearing devil — and even at that magnification, I had to revert to averted vision to pluck it from the darkness.

Now that companion has a magnitude of 9.4, which is brighter than either of the very visible companions of the South pair — and the primary in this case is only six tenths of a magnitude brighter than the primary of S 756 — so why the difficulty in seeing it?  Could it be it’s just shy?  Maybe the moon knows why.

All I can conclude is it must be part of the “things aren’t what they seem” scheme.

However, and anyway, and finally — I have now accomplished something that I’ve been meaning to do for well over a year, which is to make some kind of sense out of this Cygnetic confusion.  I can now distinguish Omicron-1 from Omicron-2, separate 30 Cygni from the scene, linger over the twin view of the Sh siblings, link Omega-2 to the correct star — and even find Omega-1.

I now have the scorecard I so sorely lacked last year.

So if you want to know who’s on first, or what’s on second, or if what’s on third instead — feel free to start here.

And if that fails, the thing to do,
is just admire the wide field view,
of Omicron-1  ……  and Omicron-2.

Clear Skies!

******************************************************************************

Update and Corrections!!!

Now, as should be obvious from the above, the reason I wrote this post was because these stars had me totally confused as to what designations belonged to which stars.   After reading Sir Jame’s South’s entries in his catalog of 1826, I can see that the confusion has been around since at least 1824.  The “brief” title of that 1826 work, by the way, is Observations of the Apparent Distances and Positions of 458 Double and Triple Stars, Made in the Years 1823, 1824, and 1825; together with a Re-Examination of 36 Stars of the Same Description, the Distances and Positions of Which Were Communicated in a Former Memoir, and it’s available in .pdf format here.

But let’s start with the confusion in The Cambridge Star Atlas, which has labeled the two stars that constitute ω-2 with the wrong prefix, “Sh”.  That prefix belongs to the stars listed in a separate publication, Observations of the Apparent Distances and Positions of 380 Double and Triple Stars, Made in the Years 1821, 1822, and 1823, and Compared with Those of Other Astronomers . . . . , which was a joint effort of James South and John Herschel, published in 1824, and available here  (scroll down to the last entry on the page).

But — the ω-2 pair is cataloged in South’s 1826 publication (the first one mentioned above), and all of those stars are assigned the prefix “S.”  So, the correct identification for the ω-2 pair is  S 755 and S 756 — and the post above has been corrected to reflect that.

But back to Sir James South:  At the conclusion of his remarks on the observations he made in 1824-25 of  S 755,  Sir James comments, “There is some reason to suppose that Sir W. Herschel has erroneously called this star ω-2 Cygni, which it certainly is not; ω-2 as far as my instruments can inform me is single.”  (p. 259 of the 1826 catalog)

The first part of that statment is correct — S 755 was NOT assigned the ω-2 designation — it was assigned instead to S 756.  Who knows why.  Of course it doesn’t help that both S 755 and S 756 show up on most star maps as ω-2.

But if you’ve read the entry above, you’ll know that ω-2 (S 756) is not single, but a double.  The reason for South’s remark becomes a bit more clear at the beginning of his entry for S 756 when you see that he identifies it as ω-3 — and I have no idea where THAT came from.  Again —  that one is actually ω-2.  At any rate, I don’t have the first clue WHAT star Sir James was referring to in the reference to ω-2 as single, and I’m not about to hazard a guess as to why he used ω-3 in connection with S 756.

All I can say is this obviously has proven to be a very confusing part of the sky for a lot of people for a long time.  So if you lose your bearings and begin muttering miscellaneous numbers incoherently, don’t let it bother you.  You’re in some pretty darn good company.  😎

DSC-60: Three wide doubles in Lyra to get you started – Zeta (ζ), Beta (β), and SHJ 282AC

Splitting Tools for Zeta (ζ) Lyra: Zeta yields to a 15X70 binocular hand held, or 8X40 binoculat mounted; 50mm scope splits it easily.

Finding and splitting these three  wide pairs on a Summer or Fall evening should be a great way to get started with doubles – and if you’re already a veteran, they’re still worth a look. Veterans may find it more challenging to give them a try with binoculars – or that little, old 50mm refractor you bought on a whim!

Naming them is a bit more difficult for SHJ 282AC is listed in the Double Star Club (and elsewhere) as OΣ 525 and may be identified on your star charts simply as HIP92833. The Cambridge Double Star Atlas lists it both ways – OΣ 525/ SH 282.  But this naming thing is a footnote – let’s get to the meat of the matter, how to find them.

First, these three are easy to find. All you have to do is locate one of the brightest stars in the sky – Vega. Then work from there. (Vega is the second brightest star in the northern hemisphere and about as close to magnitude zero as you can get. In Suummer and Fall it’s high overhead in the evening for northern hemisphere observers.)

As with most constellations, I have difficulty making a lyre out of the stars of Lyra, but I have no problem seeing two linked asterisms –  a triangle and distinctive parallelogram.

The Lyra triangle and parallelogram asterisms. This whole chart can fit in the field of many low-powered binoculars and the Vega triangle fits easily in a finder or very low power telescope field. Since the magnitude of key stars range from 3 to 6, you may need binoculars to see these asterisms in a light-polluted area, though you should be able to see Vega anywhere with the naked eye.

I always find my way about Lyra in two steps. First I find Vega and the two stars that form a triangle with it. The northern most of these stars is the famous Double-Double. The other is our first target tonight, Zeta (ζ) Lyrae. 

Zeta forms a bridge then to the rest of Lyra which is nicely marked by a parallelogram. Zeta marks the northwest corner and Beta (β) Lyrae (Sheliak), the southwest corner of this parallelogram. I always use Beta as a guide to finding the wonderful little Ring Nebula, M57. It’s about three-quarters of a degree to the east. If you’re familiar with it, you can use it as one corner of a triangle that consist of Beta, M57 and SHJ 282AC. If you don’t know  – or can’t spot – M57, just go straight to SHJ 282AC. It’s little more than a degree northeast of Beta and at sixth magnitude considerably brighter than M57. (Hmmm…the shoe fits better on the other foot!  If you’re looking for M57 then SHJ 282AC might actually be a help in finding it!)

These stars are all remarkably similar in the distance between them – about three quarters of a minute of arc. And Zeta and Beta are almost identical in position angle – so you can use Zeta to tell you where to look for the secondary to Beta and that should be a help since there’s five magnitudes difference in the Beta pair making the 8.6 magnitude secondary a little more difficult to spot in a small scope.

I, of course, used the 60mm Televue, my standard for the DSC-60 project. (For project details go here.)

John has already posted an excellent report on Zeta and Beta and you’ll find his write up here, so I won’t repeat all the details.

Zeta (ζ) Lyrae 

Stats from the Double Star Club List:

Zeta Lyrae 18h 44m.8 +37° 36′ 4.3, 5.9 44″ 150

Haas lists the secondary a little brighter – 5.6. This pair is about 154 light years from us and has spectral classifications A, F0.

I found this split nicely using a 24mm Panoptic – 15X.  I actually  started with a 24 – 8 zoom, but really didn’t like the views I was getting. The 13mm Nagler gives a really solid feel at 28X and it was fun to crank it up a bit with a 5 mm Nagler – 72X. With that last I saw the colors of this pair as silver and violet. Lots of stars share the field of view, even at 72X, but none crowd it.

Don’t take my color report too seriously, however – people seem to be all over the map on the color of these stars. Haas reports a paid of “goldish white” stars and says Smyth saw them as “topaz, greenish,” while Webb saw “greenish white, and yellow.”  John saw them as yellow and white in a 60mm – but saw both having a yellow tint when he switched to a 6-inch.  Oh boy! Time to move on to Beta.

Here’s the DSC listing for Beta.

Beta Lyrae 18h 50m.1 +33° 22′ 3.4, 8.6 46″ 149°

And here’s John’s summary of facts:

Beta (β) Lyrae (Sheliak)

RA: 18h 50.1m   Dec: +33°  22′
Mag:  AB – 3.6, 6.7  AE: 3.6, 9.9  AF: 3.6, 9.9
Sep:  AB –  46″          AE:  67″        AF: 85″
PA:    AB – 150°       AE: 317°       AF:  19°
Distance: 881.5 Light Years
Spectral Classification for A & B: B7, A8

Notice that John includes  a couple of other components. You don’t need to see these for the DSC, just the A-B components. But please note the large difference in reported magnitude between the DSC list and John’s numbers.  John list these stars as 3.6 and 6.7 – which are the magnitudes found in Haas and in the Washington Double Star Catalog.  I trust John’s sources and I can’t explain why the DSC list appears to be off – but I suggest you simply take it as a warning that the DSC numbers may not only be dated, but have some other errors in them. I include them because this is the official list for the Double Star Club certificate.

When I get looking for Beta in the scope I find it easy to confuse with the other southern corner star until I remember that one of these stars has several other bright stars in the field – and Beta is pretty much alone. I found the five magnitude range between primary and secondary made this a challenge at 15X, but a downright elegant sight at 28X. I saw the primary as white and – maybe this is a blessing – I could make out no color in the faint secondary. Haas has it as “sapphire” and Smyth – bless his colorful eyes – saw it as “pale grey.” Guess I could go with either of those descriptions, especially if I were using a larger scope  – but in the 60mm I just am not ready to say.

Now color is the hallmark of our third easy double – in fact, Webb describes it as a “beautiful miniature” of Albireo – Beta Cygni. That comparison didn’t jump out at me, but I did see a pale orange primary and blue secondary.

The other hallmark here is the name. The DSC list identifies this as “Otto Struve 525.”  Not really. OΣ 525 is the primary and the “B” component and thankfully the DSC is not asking you to split that – especially with a 60mm. That pair is 6.1 and 9.1 and just 1.8″ of arc apart!  But look at the magnitudes in the DSC listing, as well as the generous separation of 45″ and it seems obvious they are talking about another pair – a pair both Haas and the Washington Double Star Catalog identify as  SHJ 282AC.

Now honestly, I don’t understand enough about the nomenclature to know what’s most proper in this case. Seems to me it should be SHJ 282AC which gives the credit for this star to South, J. and Herschel, J. But OΣ 525 does refer to the same primary and Starry Nights Pro simply list it as HIP92833.

So if you’re going  for the DSC certificate, you’re looking at OΣ 525, but that really means the easier of two pairs – technically the AC pair.

Otto Struve 525 18h 54m.9 +33° 58′ 6.0, 7.7 45″ 350°

This combination is a whopping 1,339 light years from us and the primary has a spectral classification of G8III. Notice that spectrum puts it on the orange side of yellow, so that fits my vision of a “pale orange primary” and also fits the comparison to  Albireo where I always think of the primary as “gold.”

Can’t wait to give these three a shot with mounted 15X70 binoculars.

In the House of Hyades: Sigma (σ), Theta (θ), and Delta (δ) Tauri

And now for something entirely different — binocular binaries.

Grab yourself a cup of something warm and have a seat beside me in a comfortable chair.  We’re going to tilt back into Taurus and enter the well lighted House of Hyades.  And in case you’re mystified by the reference to the Hyades, it’s the open cluster of stars between Aldebaran and the point where the “V” of Taurus come together just to the southwest of it.  But more on that later.

Now I have to tell you, binoculars and I have never hit it off.  My eyes just don’t want to be forced into looking through two large lenses at once.  And in addition to the fighting eyeball feedback, I frequently find I’m struggling to get a precise focus.  I don’t know about you, but I seem to prefer my photons finely focused — as in well done — and most binoculars I’ve used insist on serving up half-cooked views — as in medium rare.  Hope I’m not making you hungry.

But I do have a handy pair of 7×35’s that get used occasionally for quick glances.  For instance, if I’m trying to find an elusive star, or if I see a rare mysterious light in the sky — no contact with E.T. yet, though.   But somewhere deep in the recesses of my double star cluttered memory, I remembered Greg mentioning he was having great luck with his 15×70 Celestrons.  So when I saw a pair come up for sale, I decided to grab them to see how much better they would be than the small pair I ignore.  Tonight we’re going to use both pairs.

Because of their size, I have the 15×70’s on a parallelogram mount.   I tried using them without it and my arms began to feel like jelly within a couple of minutes.  So I’ll set them up beside your chair, and I’ll use the 7×35’s to guide us through this maze of stars.   And better throw this blanket over your legs — the dampness out here is a bit chilling tonight in this forty degree air.

One thing that will strike you immediately if you compare views in these is how much brighter the field is in the 15×70’s. I mean the stars really leap out at you.  I’ve caught myself ducking couple of times!

The Hyades Cluster, home of Sigma (σ), Theta (θ), and Delta (δ) Tauri. Click on this image, and those that follow, for a larger view. (Stellarium screen shot with labels added)

Now, this area not only features two multiple stars visible to the unaided eye — Delta and Theta — but it’s rich in visual pairs of stars that form some rather eye-catching patterns.

We’re going to start this tour with the beautiful reddish-orange Aldebaran, a first magnitude star located a relatively close 65 light years away from where we’re sitting tonight — just a hop, skip, and a jump out into the near reaches of our galaxy.  In the binoculars, though, I’ve noticed the color seems to be a bit pale — more like white with a reddish-orange tinge.  Take a look and let me know if you see the same thing.  Aldebaran has an 11.3 magnitude companion located a wide 133″ from it, which I think we should be able to pick out with at least the 15×70’s you’re using, except that the transparency is rather poor tonight.  So we’ll have to come back to it on a better night.

Splitting Tools: Obviously, since this is a post describing binocular friendly pairs, all of three of the pairs described below are ideally suited for binoculars, even small ones — hand held 7×35’s work well, but if you use anything larger, mounted would be better.  But they’re also great candidates for 50mm and 60mm scopes, provided you use low magnifications of about 20x or so.  Too much magnification will produce very wide pairs, giving the appearance of regular field stars.

Sigma-1 and Sigma-2  (σ-1, σ-2)  (Σ I 11)  (STFA 11)
HIP: 21683    SAO: 94054
RA: 04h 39.3m   Dec: +15° 55′
Magnitudes: 4.7, 5.1
Separation: 444.1″ (7.4′)
Position Angle: 194°  (WDS 2011)
Distances: 152 and 159 Light Years
Spectral Classifications: A4 and A5

OK — with Aldebaran in the center of your binoculars, if you let your eyes travel just a bit to the east you’ll come to the Sigma (σ) twins, σ-1 and σ-2.  They’re a visual pair, and they form a right angle triangle with sixth magnitude 89 Tauri just to their west.  Now  Sigma-2 (σ-2) looks white to me, and Sigma-1 (σ-1) is just a slightly different shade of white — it looks like maybe it has a slight tinge of yellow.  In Double Stars for Small Telescopes, Haas describes them both as brilliant yellow, but that was with a 125mm telescope which would provide a richer color than we can see in the binoculars.

What’s that?  So you see the yellow, too!  Great, I thought maybe my eyes were being tricked by the two little 35mm barrels on this pair I’m using.

Now you can take your choice of two eye-pleasing asterisms here — either the right angle triangle formed by the Sigma twins and 89 Tauri, or the parallelogram formed if you include the 6.6 magnitude HIP 21474 to the southwest of 89 Tauri.  Regardless of which you prefer, you’re guaranteed a stellar configuration either way.  I kind of lean toward that uniquely shaped parallelogram.

Oh, and to answer your question about the numbers attached to the Sigma pair: the -1 and -2 are assigned to them based on location.  The one farthest to the west gets the one, the next one to the east gets the two.  And if you look at the chart above, you’ll see that holds true for the Theta (Θ) twins and the Delta (δ) triplets.  Pay careful attention to this astronomical trivia — there might be a quiz when we get situated in the House of Hyades soon.

Theta-1 and Theta-2  (θ-1, θ-2)  (Σ I 10)  (SFTA 10)
HIP: 20894    SAO: 93957
RA: 04h 28.7m   Dec: +15° 52′
Magnitudes: 3.4, 3.9
Separation: 341.20″  (5.7′)
Position Angle: 348°  (WDS 2011)
Distances: 157.9 and 149.0 Light Years
Spectral Classifications: G7 and A7

I remember very clearly the first time I split these two stars.  It was without a scope on a night that was very clear and transparent.   I was looking up at Taurus because Aldebaran had caught my eye, and as I was enjoying the view of it and the Hyades, I suddenly realized I was seeing two very close, but distinct stars, just southwest of Aldebaran.  Now that really caught me off guard since I had never noticed them before, so I grabbed an atlas and identified them right away.  Since then, I’ve used these two stars frequently to gauge the transparency.  On a scale of one to five, five being the best, you need a four — above average — to pull off this trick.  And dark skies help a lot, too.

If you ask Jim Kaler, he’ll tell you the jury is still debating as to whether Theta-1 (θ-1) and Theta (θ-2) are gravitationally linked.  But Theta-2 (θ-2) has a companion located a mere couple of a hundredths of an arc second away — a little on the close side, and more than a bit beyond binocular range — which whirls around its parent once every 140.7 earth days.

We’re focusing now on the area within the circle! (Stellarium image with labels added)

Now if you position Aldebaran on the northeast side of your binocular field, Theta-1 and -2 will come into view over on the southwest side.  Both of these stars are white, but Theta-1 (θ-1) seems to have a slight tinge of red to me.  What?  You don’t see it?  Here, you better have some more hot tea.  You’ll be able to see the warmer colors better that way.  🙂

OK, if you start at  Theta-1 (θ-1) and let your eyes travel a bit to the northwest, you’ll come to fifth magnitude 75 Tauri, which looks to me to be white with a slight bit of yellow mixed in there somewhere.   Now, from Theta-2 (θ-2), look over to the east and you’ll find a pair of fifth magnitude stars, 80 and 81 Tauri,  with sixth magnitude 85 Tauri extending on a line beyond them to the northeast.  And just northeast of the Theta (θ) pair is another pair of stars, fifth magnitude HIP 21029 and 6.5 magnitude HIP 21053.

Now if you look into those binoculars closely — or at the chart above — that last pair, along with the Theta twins, and the 80/81 Tauri pair, form a very unusual triangle of three pairs of stars.  And, if you’re keeping track of all this for the quiz, you can add these notes: Both 80 and 81  are telescopic doubles — 80 Tauri has an 8.1 magnitude companion 1.6″ from the primary, and 81 Tauri has a 9.4 magnitude companion at a more distant 162″.

Like I said, this area is just full of eye-catching patterns.

But wait just a second.  Before you put those binoculars down to ask another question, look a bit closer at that triangle of double pairs and you’ll see …….

(Stellarium screen image with labels added, click to enlarge the House).

And you were wondering if we would ever get there.

Kind of leaves you breathless, though, doesn’t it.  Yeah, I know — star stuff does that sometimes. I wouldn’t take off that coat, though.  There’s no heat in that house, at least not from where we sit at about 150 light years away.

Actually, I have to thank Greg for pointing out this asterism.  It really is unique, and once your eyes recognize the pattern, it jumps right out at you.

And now that we have a home, the next thing we’re going to do is jump off the roof.  So let’s climb up to the peak, where 75 Tauri is located, and we’ll make a short leap straight up from it to the northwest and come down very gently right in the middle of the Delta (δ) threesome.

A leap to the northwest from the roof of the House of Hyades lands us right in the middle of the delectable Delta (δ) trio. (Stellarium screen image with labels added, click on the chart for a larger view)

And once more, another pattern emerges before our binocular fortified eyes.

Delta-1 (δ-1)                   Delta-2 (δ-2)               Delta-3 (δ-3)
Σ 1746                                      BUP 56                       H VI 101
HIP: 52913                                20542                           20648
SAO: 137808                            93907                           93923
RA:  4h 22.9m                     4h 24.1m                         4h 25.5
Dec:   +17° 49′                      +17° 27′                        +17° 56′
Mag:         3.75                              4.80                               4.30
Sep:                                 13.8′ from -1                43.2′ from -2
Dist: 153.2 LY                       145.9 LY                        147.9 LY
Spec:          K0                                  A7                                  A2

The Delta (δ) trio of stars forms a very recognizable triangle of just slightly more than ninety degrees.  As I look at them, Delta-2 and -3 appear to be the same shade of white, and Delta-1 seems to me to have a slight tinge of yellow to it.   You can see that, too?  Wow, our eyes must be on the same wavelength!

OK, now look closely at this area and you’ll see four pairs of stars to the southeast of Delta-2 (δ2) that form an interesting pattern.  They caught my eye because the first two pairs (1 and 2 on the chart above) are arranged parallel to each other, as are the last two pairs (3 and 4) which point a bit more toward the south.  If you spend enough time here, your eye will no doubt detect other patterns.  I’ll leave that to you while I pour us some more tea.

Now the Delta (δ) trio are not gravitationally linked, which you can see if you look at their distances as shown above.  But each of them have companions, although those of Delta-1 and -2 are detectable only with spectroscopes or very large instruments.  The two companions of Delta-3, however, can be seen in a small to medium telescope.  The brightest is a 7.5 magnitude star at a tough distance of 1.5″, and the other is an 8.7 magnitude star located at a much more detectable distance of 77″.  I haven’t looked at these with a scope yet, but I’m filing a mental note right now to come back to them.

The Hyades

As we sat down at the beginning of this evening, I mentioned the Hyades cluster and described it as consisting of most of the stars between Aldebaran and the point where the “V” comes together at Gamma (γ) Tauri.  As you look at this area in the binoculars, or on the first chart above, it’s kind of difficult to form an image of a single cluster in your mind.  Instead, as we’ve just seen, what stands out is several groupings of stars.

So to make the “clusterness” of this cluster more visible, I listed the distances of all the labeled stars in the first chart.  I started with the Sigma (σ) pair and then worked my way to the southwest until I came to Gamma (γ) and then back up to the north.  Now Jim Kaler says the average distance of the Hyades cluster is fixed at about 152 light years, and that number begins to make a lot of sense if you look at the numbers on the chart below.

Just a quick glance at the distances you see on it shows that all but a few of these stars lie within a narrow range of 142 to 159 light years from us.  Out of the twenty-three stars in that list, only the four in red clearly stand out as non-members because their distances are nowhere close to that range.  The only one there is really any doubt about is HIP 21053.

And for a view of the Hyades in three dimensions — including a movie (!) — take a look at this site.

OK, what do you say we drop back in through the roof of the House of Hyades and see if the Hyadeans have any thing to eat.  Of course, I’ve never eaten there, so we might be better off to just get off this cold, damp deck, and go see what we can find in my kitchen.  At least it will look like something you’ve seen before.

And since you tolerated that maze of numbers on the chart rather well, we’ll just forget the quiz.  The images of all those star patterns in our memory will keep us mentally occupied for a while, anyway.

Cup of tea and a slice of cake?

(WDS data updated 9/9/2014)