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The 60mm Philosophy: Learn to Savor the View

OLYMPUS DIGITAL CAMERAYou’ll come across it sooner or later if you pick up an astronomy magazine or scan the many on-line astronomy forums.  An author will make an off-hand comment, or someone on one of the forums will state categorically:  “A 60mm refractor is a mere toy . . . “; “Don’t bother with one of those things since you can’t see anything with them anyway”; “There’s no substitute for aperture – get a real scope.”   Etc., etc., etc., ad infinitum.

Well . . . . . . . . yes,  and no.   Mostly no, but a qualified no.

The first bridge to be crossed is the one that leads to optical reality:  A lens is a lens is a lens —– meaning  aperture is aperture is aperture.  A 60mm lens can’t collect any more light than its frugal 2.36 inches of diameter will allow.  So the views in a 60mm scope are limited, yes.  But so are those in a five or six inch refractor, in an eight or ten inch SCT, in a ten or 12 inch reflector.  When you push one of those scopes to their optical limits, the stars become faint and difficult to resolve, just as they do in a 60mm refractor.  Optical reality being what optical reality is, the smaller the aperture, the sooner you discover those limits.

But that doesn’t mean you should give up on a scope with a 60mm lens – no more than you would give up on a four inch refractor in the middle of an observing session  for a six inch refractor you don’t have.   The key to enjoying what a scope has to offer is to work within the limits of the lens in the scope that happens to be in your hands.  Put another way, adopt a lesson from everyday life and apply it to optics: make do with what you have, and turn a disadvantage into an advantage.

Applied to a 60mm lens, that means taking a deep breath and recovering some common sense – something which tends to be overwhelmed by the insidious creep of aperture envy.  Point that 60mm scope at a target within its range, not at one of the Abell galaxy clusters.

What lies within range of a 60mm lens?  Many more objects than many people realize.  Try the moon, first – then Jupiter, then Saturn.  Then take a look at a few deep sky objects – the Pleiades for starters, the Double Cluster in Perseus, M31 (the Great Andromeda Galaxy), Collinder  69 (the open cluster surrounding the head of Orion), and don’t skip the Great Nebula in Orion, M42.

And double stars?  There are too many to list, but hit the showpieces for sure:  Albireo, Algieba, Almach, Beta Cephei, Castor, Cor Caroli, Delta Cephei, Delta Herculis, Gamma Arietis (Mesarthim), Gamma Delphinus, Graffias, Epsilon Lyrae, Eta Cassiopeiae, Iota Orionis, Izar, Meissa, MizarNu Draconis (“The Dragon’s Eyes”), Omicron Cygni, Polaris, Rasalgethi, Xi Bootis, Xi Cephei   . . . . . . . . . the list goes on and on and on.

My f/16.7 60mm refractor crafted with a 1000mm focal length Carton lens and a rescued Unitron finder.  (Click on this or any of the other images for a larger view).

“The Silver Streak”:  my f/16.7 60mm refractor crafted with a 1000mm focal length Carton lens and a rescued Unitron finder. (Click on this or any of the other images for a larger view).

Ah, but I can hear the distant clamor and clatter of objections as they bound over the hills and through the dale and echo in the aluminum hollows of my hallowed f/16.7 sixty millimeter refractor tube: “Yeah, you can see that stuff, but it’s hardly satisfying.

Look – you have to adopt a different approach  . . . . . . .  arrest that demanding and driving urge for more and more aperture  . . . . . . .  you’ve got to slow down . . . . . . . pause to get your breath  . . . . .  and give the subject some serious thought for at least a few moments . . . . . . because the inescapable fact is this: you have to learn to appreciate the sixty millimeter images for what they are.   What they are . . . . . . . are different images than what you would see with more aperture.

And of course, they have to be!
Because you’re working with less light!
Which means it’s a different kind of light!

All of which means you have to learn to appreciate the basic fact that the image in the eyepiece end of your 60mm refractor has a different quality to it, a different flavor – one you have to learn to savor, and even understand.   It’s that one word – different – on which you have to stay firmly focused.  Until you begin to realize that, you’ll never be able to appreciate what a sixty millimeter instrument offers you so graciously:

“There’s more than one way to look at a universe!”

Let me show you.

Turn that 60mm lens to Mizar, the second star from the end of the handle in the Big Dipper asterism of Ursa Major.  Drop a low magnification eyepiece into the diagonal – let’s say 25mm or somewhere close.  Now line up the scope on Mizar, focus carefully, and as the image comes into view, you’ll be greeted with the second and fourth magnitude radiance of the Mizar pair, separated by about 14 seconds of arc – and opposite them in the east quadrant of the eyepiece at a distance of twelve minutes of arc you’ll spy fourth magnitude Alcor.   About halfway between Alcor and the Mizar pair, dimly punctuating the black sky with its eighth magnitude light, is a star known as Ludwig’s Star (Sidus Ludoviciana), which was once mistaken for a planet, and hence was named for King Ludwig of Bavaria.

The MIzar pair is seen here to the left of center, Alcor is opposite them at the right of center, and the star between them is Sidus Ludoviciana, Ludwig's Star. (East & west are reversed to match the refractor view, click on the image to enlarge it).

The MIzar pair is seen here to the left of center, Alcor is opposite them at the right of center, and the star between them is Sidus Ludoviciana, Ludwig’s Star. (East & west are reversed to match the refractor view, click on the image for the dark sky view).

Now sit back and let your eyes rove around that field of view.   Take it all in slowly, let the starlight work its magic – and you’ll begin to realize there is a certain quality to that view that is somewhat subdued, pinpoint sharp, and very . . . . . . . neat.   There is just no other word for that characteristic of the view – it’s very prim, very proper.   Every single star in that field of view is a precise pin prick of white light poked into the black-as-velvet darkness;  every single star in that field of view looks as if it’s right where it belongs, and very satisfied to be there, too.  The brighter stars don’t overwhelm the dimmer ones the way they might in a much larger scope — there seems to be a mutual degree of stellar respect for the non-optical principle of allowing each individual star its own space in which to shine.

Now of course you can’t see any 12th magnitude stars in this view – but you don’t need to!  Just forget about what this image would look like in a larger scope – don’t even think about it!  Banish those tempting impure thoughts of aperture envy from your mind forever!   That 60mm scope in your hands right now is all the aperture you have available at this particular moment in time — look and study and focus your thoughts on that image, the one entering your eyes right NOW!   It doesn’t need to to measure up to what you would see with more aperture  — it can’t, because it’s not the same: it’s different!

I run into that problem myself all the time.  I have 60mm refractors mounted on my four, five, and six inch refractors.  And believe me, there is nothing that will make the view in a 60mm scope suffer more than peering into it immediately after viewing the same object in the larger scope.  I have to jar myself back to reality, re-plant both feet firmly on terrestrial ground and remind myself – hey, it’s a different view!

And there’s one other thing to keep in mind:  If, for example, you had a four inch refractor and were constantly attempting to look at objects beyond or right at the limit of its range, sooner or later (probably sooner) you would find yourself growing tired of using it.  But if you backed off of the magnification for a while and picked a few objects well within the range of that four inch lens, suddenly you would be gazing at those tack sharp views with their sparkling qualities that drew you to the scope the first time you looked through it.  Viewing through a 60mm refractor is no different – stay within its limits and it will provide some very aesthetically pleasing views.

Yes, you can take a 60mm scope and push it to its limits.  I’ve done that many times, but that’s a different kind of viewing aimed at one specific object with one specific intent.  For example, I’ve split Delta Cygni in a 60mm scope a couple of times, which is a real challenge.   Achieving it is very satisfying – BUT – it’s a lot of work, exhausting even,  and the image is anything but satisfying.   It’s one of those things you do to test both your limits as well as those of the scope.  But in no way is it an aesthetically pleasing view.

The venerable Tasco 7T-E (f/16.7) on its native mount.

The venerable Tasco 7T-E (f/16.7) on its native mount.

To remind myself of the real beauty that can be found in a 60mm scope, I’ll take a view of Omicron-1 and -2 Cygni anytime – you can’t get that same view in a larger scope.  Or that beady little greenish dot of secondarial light tucked up right against Rasalgethi’s burnt-orange primary – nothing rivals the decoration those two orbs of light bring to an eyepiece in a 60mm refractor.

And I’ll be happy to feast my eyes on the ethereal beauty of Eta Cassiopeiae any time – the orderly precision of that view is totally unlike what I see in a four inch refractor.   And I wouldn’t dare forget the thrilling triple white delight served up by Beta Monocerotis in a 60mm refractor – in my Tasco 7T-E at 59x, the BC pair are so close together you can’t wedge an up or a down quark between them, even though they’re clearly two distinct circular points of light.

The focuser end of a Lafayette f/13.3 60mm refractor.

The focuser end of a Lafayette f/13.3 60mm refractor.

And that brings up the issue of optical quality, which is a curse visited on the innocent 60mm refractor by the evil department store versions that were pedaled for years, especially at Christmas time.  That curse left a mark on the 60mm reputation that still lingers today.  Needless to say, stay away from anything in a thin cardboard box that advertises 500x with Hubble-like images of the planets and galaxies splashed colorfully across the exterior.  You best bet is to pick up an older used 60mm with labels like Tasco (roughly pre-1970), Unitron, Lafayette, Selsi,  Monolux, Pentax, Carton, or Swift.  I’ve even put together several of my own scopes using Carton lenses and cells, aluminum tubes, purchased focusers, and a can of spray paint.  And don’t  hesitate to mount them on solid modern mounts – avoid the spindly metal-legged tripods that come with some of the older scopes.

NOW  –—–  the next time a clear night rolls around, lock up that large refractor-reflector-SCT-or-whatever-you-have in a closet, station a ravenously hungry growling beast in front of the door to remove all temptation ——

and then turn to that innocent, lonely, neglected 60mm refractor sitting forlornly over in the corner on its mount,  grab the tripod, pick the whole thing up and walk it outside, place it on the ground, pull up a chair, point the tube up into the sky at an appropriate object, drop a 20mm eyepiece into the diagonal, dial up a sharp focus, sit absolutely and reverently still —– and let those distant photons that have been blazing their way blindly to you for tens or hundreds or thousands of light years, slip through that 60mm lens, pass through the lenses of the eyepiece, and magically register their electrical impulses in the dark depths of your mind.

You’ll be a better person for it.   :mrgreen:

Another home built 60mm refractor -- this one has a Carton 800mm focal length lens in it, with a 6x30 Celestron finder and an Antares focuser attached. The dew shield is an exotic plastic container that once was full of yogurt.

Another home built 60mm refractor — this one has a Carton 800mm focal length lens in it, with a 6×30 Celestron finder and an Antares focuser attached. The dew shield is an exotic plastic container that once was full of yogurt, but now it yearns for a culture of starlight.

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.

Epsilon (ε) Geminorum: “A Star with a Distant Companion, on Castor’s Right Knee”

Careful now, careful!  Get it centered, you don’t have much time ………  got it!   Now, look in the eyepiece and get it focused quickly, easy there — HURRY, the clouds are almost here   …………….    THERE IT IS!   Oh, wow, there’s that luscious yellow again, and the scatter of stardust surrounding it on that black velvet background  —-   WOW!!!!   …………..    Hold it.   Hang on to your wow  ……….     LOOK!    It’s fading already  ……………….    it’s gone!   IT’S GONE!      Arghhhhhhhhhhh!!!!!!

Real-life drama here on the rain infested, wind blown, hail strewn, snow socked northwest coast of Oregon.   The day before — and I exaggerate not one iota — there were 60 mph winds in the morning, followed by 2.25 inches of rain in the afternoon, followed by three inches of snow in the evening — and people actually think of this as a vacation destination?

So when I saw huge holes in the clouds the following evening, I couldn’t resist — even though I knew the Sky Gods were just itching to lure me into sucker hole hopping again.  Which they did.  And you just read what happened.

But that was only the first half of it.  The second half came after I went in the house to put on a warmer coat and came back out, only to find the heavens were throwing hail at the ground.   Arghhhhhhhhhhh!!!!!!  again.  Why do I do this?

There’s no quick answer to that question, but in this case the cause was definitely the beautiful deep yellow of Epsilon (ε) Geminorum.  My first addicting glimpse of its glamorous yellow was back in late December after reading Sissy Haas’s description of it:

60mm, 25x: Beautiful pair at low power!  It’s a brilliant Sun-yellow star with a tiny speck of light next to it.  They’re super-wide apart but look like a couple.”

Double Stars for Small Telescopes, p. 77

That did it for me.  I had to look, and I did, and I was very impressed — so I made great plans for this beautiful yellow-saturated primary and its glistening secondary.  But the weather had other ideas, so in the meantime I was left with a craving that increased exponentially with every cloud-covered night.

To tide myself over, I locked up a mental image of that luscious yellow primary in a photon reinforced memory bank, and hoped it could resist the persistent attempts of wind and rain to gnaw through the membrane walls.  They were within a few arcseconds of succeeding when I surrendered to the sinister evils of sucker hole hopping once more.  I know, I know, it was destined to be futile.  But I couldn’t help myself — I had to have a second look.  I had to see it again.  I was starved.  I was helpless.  I was desperate.  My resistance was no longer resistant.

And despite the frustration that resulted, I would to it again in a micro-second of a second.

Epsilon (ε) Geminorum    (Mebsuta)  (S 533)  (H VI 73)    HIP: 32246   SAO: 78682
RA: 06h 43.9m   Dec: +25° 08′
Magnitudes:  3.1, 9.6
Separation:   110.6″
Position Angle:  95°  (WDS 2002)
Distance: 903 Light Years
Stellar Classification: G8

In her description of Epsilon (ε), Sissy Haas also referred to an observation by Admiral William H. Smyth, so I went to my trusty copy of The Bedford Catalog to see what he had to say:

A star with a distant companion, on Castor’s right knee; it is [at] about 26°, or rather more than one-third of the distance, from Procyon towards Capella, where a line led from Rigel through Betelgeuze also reaches it.  “A” 3, brilliant white; “B” 9 ½ , cerulean blue.  This wide object is 73 H. VI; registered by Sir William in 1782, with a distance of 110″.48, but no angle of position given.  It was first measured by S.:  Pos. 93° 42′   Dist. 111″.57    Ep. 1825.04.

This star is called Mebsuta, from al-adhirá al mebsútah, the out-stretched arm; i.e. Castor and Pollux, the bright stars of whose heads form the VIIth Lunar Mansion.”

The Bedford Catalog, Willman-Bell: 1986, p. 157

There’s a wealth of references and information in that quote, so it’s worth going through it carefully and picking it out to learn more about the focus of my irrational obsession.  Let’s start with the Admiral’s directions to it.

Now Epsilon (ε) is really not at all hard to find, and the way I did it (which I thought was the most obvious) was to start at Alpha (α) Geminorum, better known as Castor, and proceed southwest to the next star in the stick figure that forms that side of the constellation, which is Tau (τ).  From there continue southwest along the stick figure schematic for about twice the distance separating Castor and Tau (τ), and you’re there.

Follow along on this chart with the Admiral and I, and one of us will get you to where you need to go! (Stellarium screen image with labels added, click to enlarge).

But the Admiral had a more cosmic outlook when he formulated his directions, managing to cast Epsilon (ε) in the context of a wide swath of the sky.  And there’s an elegant simplicity about each of his approaches which mine lacks entirely.

First:  “. . . it is . . . rather more than one-third of the distance, from Procyon towards Capella . . .”  — and it is!

And second:  “. . . a line led from Rigel through Betelgeuze also reaches it.” — and it does.  And actually, I prefer this one over the others.  By the way, that spelling of Betelgeuse is the Admiral’s, and I’m not about to alter it.    Never argue with the navigator when he’s at the helm of the ship.

We’ll skip past the color for just a second and go onto the next part of his statement  — “This wide object is 73 H. VI; registered by Sir William in 1782 . . .”  —  which is a reference to William Herschel, who cataloged Epsilon (ε) as a double on February 2nd, 1782, and the Admiral’s “73 H. VI” is Sir William’s catalog number.   In the intervening two hundred plus years since his discovery, the order of those characters has been changed to H VI 73, the Roman Numeral “VI” being Herschel’s designation for separations of one to two arcminutes — and this one barely makes the cut.

And then the Admiral adds cryptically, “It was first measured by S.:  Pos. 93° 42′   Dist. 111″.57    Ep. 1825.04.”  That is a reference to Sir James South, who observed Epsilon (ε) on two occasions — December 29th, 1824, and February 6th, 1825 — and numbered it as DXXXIII (533) in his catalog.  If you look at Sir James’ separation and position angle measurements and compare them to the current WDS numbers, you’ll see the secondary’s position has barely changed in the 187 years since his last measurement.  Which is rather surprising, since the secondary is considered to be unrelated gravitationally to the primary.  Kaler mentions that the secondary is thought to be the same distance away as the primary — and if that’s the case, the two stars are essentially traveling in tandem through the galaxy.

Now let’s return to the color.  Admiral Smyth describes the primary as white, as did William Herschel, who ignored the secondary’s color.  South described the secondary as blue and ignored the primary’s color.  But — at least we have agreement between the Admiral, South, and Haas on the secondary.  So why no consensus on the primary?

I saw a very rich yellow, Haas saw “Sun yellow,” and its spectral classification of G8 (see this chart) means it’s firmly in the yellow camp and inching tentatively towards orange.  If it was classified as G2, as the Sun is, it would be tending toward white.  Jim Kaler describes the primary as being in a “rather advanced state of aging” and puts its surface temperature at 4360 Kelvin, which is considerably cooler than our sun’s 5777 Kelvin — another reason for Epsilon (ε) to favor yellow over white.

Delicious, luscious, glamorous, gleaming, and uniquely saturated in yellow, with a hint of cerulean blue in the secondary. East and west reversed to match the refractor view. Turn out the lights and click on the image to be suitably hypnotized by the Mebsutian magic.

So even though everything points solidly toward yellow, the truth is that star colors often defy such rational stellar logic.  It may even be that in this case the larger apertures in use by Herschel (twelve inch f/20 reflector) and the Admiral (long six inch refractor, focal length unknown) had a bearing on the color.  I’ll leave it there, except to say that a 60mm refractor is the ideal instrument for this star because it doesn’t overwhelm it with aperture ……  and that I really, really, really  liked the yellow I saw!

And then there’s that mysterious comment by the Admiral about the VIIth Lunar Mansion  …….  what the heck is that????   I was thrown a bit out of focus by that one, but it turns out it’s a reference to an Arab and Chinese custom of dividing the passage of the moon through the sky into twenty eight sections, or Mansions — and most of Gemini resides in the seventh Mansion.  And what that really  means is this:   while Castor and Pollux reside in luxurious celestial comfort as they wheel their way through the sky, my chattering teeth and I sit beneath them peering through a telescope as moisture runs off the bill of my Star Splitting hat and freezes on contact with the ground.

Finally, there’s that unique name, Mebsuta.  According to a couple of different sources (Kaler and Allen {scroll down to p. 235}), the correct translation of al-adhirá al mebsútah is the “outstretched paw,” which belongs to an early Arabic lion, since at one time, both Zeta (ζ) and Epsilon (ε) represented the two paws of a lion.  Zeta (ζ) is also known as Mekbuda, which refers to the “folded paw” of the lion.  The Admiral has Mebsuta as the “outstretched arm” of Castor, which at least has the merit of fitting it into the current configuration of the constellation.   But regardless of which interpretation is correct, I’ll always think of the “outstretched” limb as reaching for the cerulean blue of the 9.6 magnitude secondary.

And in tribute to the raging weather of Oregon’s north coast (which only differs from the anything but peaceful north Pacific in that it lacks thirty foot waves), I’ll end with this translation of Homer’s Hymn to Castor and Pollux as translated by Shelley. Homer portrays the appearance of the Gemini twins here as a sign to Greek sailors of the coming of spring and calmer seas.

Here’s hoping this will break the weather curse.  😉


Ye wild-eyed muses! sing the Twins of Jove,

.    .    .    .    .     mild Pollux, void of blame,
And steed-subduing Castor, heirs of fame.
These are the Powers who earth-born mortals save
And ships, whose flight is swift along the wave,
When wintry tempests o’er the savage sea
Are raging, and the sailors tremblingly
Call on the Twins of Jove with prayer and vow,
Gathered in fear upon the lofty prow,
And sacrifice with snow-white lambs, the wind
And the huge billow bursting close behind,
Even then beneath the weltering waters bear
The staggering ship — they suddenly appear,
On yellow wings rushing athwart the sky,
And lull the blasts in mute tranquility,
And strew the waves on the white ocean’s bed,
Fair omen of the voyage; from toil and dread,
The sailors rest rejoicing in the sight,
And plough the quiet sea in safe delight.

(From Allen, p, 228)

Clear Skies?  😎

The “Silver Streak,” the hail-repelling Carton lensed 60mm f/16.7 refractor that had the honor of sucker hole hopping with me beneath scurrilous skies. (Click for a closer look)

A Star for All Apertures: H III 111 (Σ 758)

September 20th, 1783, about 4 AM

It had been clear and comfortably cool most of the night, with a few thin clouds slipping past occasionally, but now the temperature was beginning to drop and the dampness was coming up as the morning dew formed across the grass covered landscape.  Silence ruled everywhere, except behind the garden, where the creaking and groaning of the twenty foot long Herschel telescope punctured the calm air at random moments.

Wrapped in a long wool coat to ward off the dampness, William Herschel was perched comfortably at the eyepiece, while his sister, Caroline, sat in a small enclosure below the telescope.  From time to time, he would call down right ascension and declination coordinates, and she would record the information while referring to a copy of Flamsteed’s Atlas  Coelestis which she kept open on a desk in front of her.

With no warning, he suddenly leaped from his chair and called down to his sister to come upstairs immediately.  Accustomed to his sudden and unpredictable outbursts of enthusiasm, Caroline climbed the stairs slowly, and following his frantic gestures, walked over to the eyepiece, bent down to take a look and hovered there for about twenty seconds, then looked up at Sir William with a quizzical expression on her face, bent down and looked again, only longer, and then, quite suddenly, exclaimed: “Well shivering secondaries, Will!  If that isn’t the most beautiful thing I’ve ever seen, I’ll sell all my Naglers!”

And that, fellow Star Splitting enthusiasts, was the morning Sir William discovered the gem we’re about to dissect in detail.  😉

(Tip: In the link above to the Atlas Coelestis site, scroll a bit more than half-way down in the box at the left to see Flamsteed’s chart of the Orion-Eridanus-Lepus area).

H III 111  (Σ 758)  (AE also identified as S 493)     
HIP: 26494   SAO: 132385
NOTE: AB is Σ 757;  AC, AD, and CD are Σ 758
RA: 05h 38.1m   Dec -00° 11′
*****   Magnitudes     Separation      Position Angle       WDS Data
AB:         8.0, 8.3                 1.5″                   240°                     2008
AC:         8.0, 8.7              51.4″                     87°                     2003
AD:         8.0, 8.5              41.5″                     79°                     2002
AE:         8.0, 8.7            138.3″                   263°                     2003
CD:        8.7, 8.5              11.2″                   298°                     2006
Distance: 741 Light Years
Spectral Classification: All B6

I’ve been curious about this multiple star since I first came across a reference to it in Sir William’s Double Star Catalog.  His description there includes precise, if cryptic, directions on how to get to it:

Treble. About 1-1/4 degree n. following epsilon, toward alpha Orionis. The two nearest of the third class.”

(From: William Herschel’s Double Star Catalog)

The “third class” is a reference to his cataloging system, which was based on the separation between stars.  In this case, the Roman numeral “III”, which designated separations of five to fifteen arcseconds, was used to describe the CD pair.

Which also pretty well explains the origin of the unusual designation, H III 111, of this multiple system.  You’ll actually find it on most charts as Σ 758 (Struve 758), but somehow that label lacks the uniqueness conveyed by H III 111.  And unique this multiple star certainly is.

Since Sir William’s directions are still good 228 ½ years later, we’ll just follow along to get where we need to go.

Orion, with the two stars mentioned in Herschel’s directions, Alpha (α) and Epsilon (ε), labeled here.  (Stellarium screen image with labels added, click to enlarge)

The “epsilon” mentioned above in Herschel’s catalog description is Epsilon (ε) Orionis, also known as Alnilam, which is the center of Orion’s three belt stars. His description, “following epsilon,” means our target is east of Epsilon (ε), which you can confirm (once we have it located) by looking into your eyepiece (with the drive turned off!) and watching H III 111 follow Alnilam’s apparent motion across the field of view. But he also said something about 1 1/4 degrees north, so let’s position Alnilam at the west edge of our field of view, and then nudge our telescope very slowly north (it won’t take much!) — and if you watch the northeast edge of the field, you’ll see this image come into view at low magnification:

Alnilam is wedged in the west corner here, and H III 111 is just coming into view in the northeast corner.  (East & west reversed to match the view in a refractor, click to enlarge)

The pair of close stars your eyes are attracted to first are AB and CD (they’re labeled in the sketch below).  “B” is almost glued to “A”, at a mere 1.5 arcseconds of distance, and requires at least five inches of aperture in average seeing conditions to be seen.  On the other hand, 8.5 magnitude “D” is much more friendly to prying eyes at a distance of 11.2 arcseconds from “C”.  And drifting to the west at just beyond a full two arcminutes of distance, and leading the whole complicated complex through the sky, is 8.7 magnitude “E”, which is easily seen in either the sketch above or below, just to the left of AB.  There’s another star on the east side, almost in a direct line with all of the others, which looks like it could be part of this system.  It isn’t — but it does serve to balance out the visual view of this group of stars.

East and west reversed again, click for a larger view.

Now the thing I really like about this quintuple grouping of stars is — as the title states — that there’s something here for any aperture.    On that first sight of H III 111 in a 50mm or 60mm scope, your eyes gravitate to three stars: AB, CD, and E.  All three of them are relatively dim, and if it weren’t for the fact that they’re almost in a straight line, your eyes would pass right past them in search of more stimulating visual material.

But, if you care to be persistent, you can pry “C” and “D” apart with either of the small apertures.  I did it in my 50mm Zeiss f/10.8 with an 11mm TV Plössl (49x) and a 7.5mm Celestron Plössl (72x).  In the 11mm eyepiece, the two stars could be seen clinging tightly to each other, with maybe a hair’s width between them, while the 7.5mm Plössl produced a definite separating slice of dark sky in the intervening stellar gap.  Although that view would never win any awards for radiant brilliance, it was just tantalizing enough that I was reluctant to move over to the 60mm scope.

However, I eventually did — and as you would expect, the view in the 60mm scope was about ten millimeters better.  Seriously, confined as we are here between the upper and lower ends of the eighth magnitude bracket, that ten millimeter difference was noticeable.  In my f/13.3 version of the sixty millimeter refractor, the 11mm TV Plössl (73x) view was pretty much the equal of what the 7.5mm Celestron had been in the 50mm scope, although just a bit brighter.  When I put the 7.5mm eyepiece (107x) to work in the 60mm scope I was back to dim, but it was still a stunning view — when it stopped bouncing around like a mad hornet confined in a jar.  The seeing on that particular night was poor, somewhere between a I and a II (on this scale), but at unpredictable intervals, it would suddenly improve for as much as a couple of minutes.

But — a few nights later, with seeing equal to about a IV, I was caught completely by surprise when I took another look at the CD pair in the 60mm scope.  With the 20mm TV Plössl (40x) placed provisionally in the diagonal for locating purposes, both of those stars were separated just as clearly and cleanly as if I was using twice the aperture  — something I really hadn’t expected to see.  I suppose Mother nature was providing me with a tantalizing reminder of how much easier stable seeing can make things  — which really  would have come in handy later on, as you’ll soon see.

East and west still reversed in the sketch, click to enlarge!

Now the view of the CD pair improves by several hundred percent when you increase the aperture to 90mm or more.  I’ve viewed H III 111 in an inexpensive 90mm Orion refractor, a more expensive 100m refractor, and an f/15 127mm refractor at low magnification, and in each case, the CD pair greets you immediately and separately at low magnification, as in the sketch at the right.  No fuss, no strain — you would never guess the two of them appear as one star in smaller apertures.

But to reveal the duplicity lying deep within the AB pair, you’re going to find you need at least five inches (127mm) of aperture, steady seeing, and an absence of atmospheric muck, which is something that clogs the local coastal air at this time of the year.  Most people would call it moisture, but I prefer muck because it’s like looking through a thin layer of mud.

Bright stars, such as Alnilam, look like they’re surrounded by a glowing cloud of nebulosity that’s busy chewing away at the smooth round edges of the star, and faint stars become dim or disappear into it entirely — kind of like quicksand.  I wouldn’t even bring it up, except that every time I tried to pull the AB pair apart in a five or six inch scope, all I got was elongated streaks — and after several attempts under those conditions, my patience was reaching an elongated stage as well.

But it’s at the larger apertures that this quintuple system really comes alive, so one way or another, I intended to see it for myself, even if it took until April.  Remember, Sir William and Caroline were looking at it through a 20 foot long reflector with a 12 inch mirror, so despite the fictional reaction I portrayed above with a modest amount of imagination, their view must have been spectacular.  I can’t approach anything of that sort, but I knew I could improve considerably over the 60mm view.

So I waited  ……….  and waited  …………  and waited some more  …………….  and then some more  …………..   heck, the rain and clouds were so thick during all that waiting that  my eyes almost became permanently dark adapted.

But finally, on February 27th of the current year — in case you’re keeping track, that would be 228 years and five months after Sir William discovered this gem — I managed to coax an hour of clear skies out of the Sky Gods, the last half of which was invaded by the wet, high altitude muck I’ve described above.

Just a little bit longer and I could use it to poke holes in the clouds ……….. click for a longer view.

I was using the five inch f/15 D&G refractor shown above, which miraculously landed in my hands several weeks earlier, and was sure I could crack the AB pair with it even though I hadn’t had any luck in its earlier attempts in the celestial muck.  But this time, I intended to sit there through the next cycle of rain-hail-snow-sleet-wind — or whatever else the Sky Gods threw my way — until I got it.

If only the evening sky looked like this more often! (Click to enlarge)

I started with a 30mm Take LE (64x) for the relatively wide view and found “C” and “D” dancing separately, but in unison, so I began an upward migration into the ethereal realm of higher magnification.  The D &G has a focal length of 1905mm, which almost matches the focal length of an eight inch f/10 SCT (2000mm) — meaning the “X” factor increases quickly if you’re not paying close attention to it.

With noticeably more light gathering ability than a four inch refractor, I thought I might meet with a successful glimpse or two in a 20mm TV Plössl (95x), but no such luck — the moisture-laden muck had already begun to invade.  I had what might have been a glimpse of the pair with my next move up, a 15mm TV Plössl (127x), but the image had now decided it was time to jump up and down and sideways.  Instinct whispered to me about that time, telling me to make a desperate lunge into the land of Barlow — either do what it took to get it now, or risk sitting here for the next week or more, dripping in the wind and rain, waiting on a suitable sucker hole.

With my back wedged against the metaphorical wall, I reached into my coat pocket, extracted a plastic bolt case, removed the top, and pulled out the secret weapon —  a 2.4x Dakin Barlow, which alters the “X” factor in long magnified leaps.  Back to the 30mm Tak LE, which magically became a 12.5mm eyepiece (152x) when I slipped it into the Barlow — but no luck.  I tried a 24mm Brandon next, which was transformed into a 10mm Brandon (191x) — maybe, not quite sure really, lots of hopping going on.  Then, on to the 20mm TV Plössl, now in it’s 8.3mm incarnation (230x), and the hopping was almost hopeless.  And the image was disappointingly dim.

Even with a five inch refractor, magnifying two almost glued-together eighth magnitude stars two hundred and thirty times tends to filter out a lot of photons.  And when the image is jumping very energetically all over the field of view, the few photons that find their way to your eye don’t stay there for very long — micro-seconds at the most.  But I kept staring, and the image kept hopping, and the atmospheric muck kept increasing, which kept dimming the image even further — but I kept staring anyway.

Back when I started with the 30mm Tak at 64x, “C” and “D” were two well-rounded orbs of light.  But now, mired in the muck at 230x, they were two oblate, moth-eaten smudges of something or other that you would never mistake for points of light.  I knew deep in the depths of my starlight starved soul that I was walking the equivalent of an optical plank, and I was within a few steps of the end of it now.

And then I caught a glimpse of two distinct points of light where AB was.  Not for long — in fact, if I had blinked right at that moment, I probably would have missed them altogether.  I eased back from the end of the plank and looked again.

Yes!  There they were!   ………………….

And there they went      ……………………………………

A whole lot steadier looking than they were! This would be equivalent to about one-tenth of a one second frame if it was from a movie! (Click to lose this caption)

But they came back several times, and a few of those times, I got a very distinct view of two very separate, almost round dots of very small light.  It was strange — I had expected to see two stars about the same diameter as “C” and “D”, but instead they were about half of that.

Well, heck, what happens if I promote the 15mm TV Plössl to a 6.25mm version with the Barlow?  305x, that’s what, and mostly mush.

I edged carefully away from the optical abyss beyond the end of the plank, went back to the 230x view, and managed a few more glimpses of “A” and “B”, separated by about a photon’s worth of width — and then they morphed into mush, too.

So I retraced my steps in reverse — 191x, 152x,127x, 95x, and finally to 64x — and as fast as I moved in reverse, the incoming muck moved even faster.  The view didn’t improve one smidgen of an iota as the magnification dropped and the field expanded.

I looked up at the sky for the first time since I had started with the Barlow — and the only thing I could see was a smeared image of a crescent moon over in the southwest, swimming in a sea of haze and elongated gray clouds.

Well   ………….   geez   …………………..   what a revelation that was.

But I had what I came for, and if it was hardly a satisfying image, it was still a very tantalizing hint of what would be possible under better conditions.  And this being the north coast of Oregon in February, I was really darn lucky I had captured it.

But I do plan on returning with a six inch refractor, and probably an eight inch SCT, too, when the skies eventually re-open for business.  I would love to get at least 1/24 of a taste of what Caroline saw (“Well shivering secondaries, Will!  If that isn’t the most beautiful thing I’ve ever seen, I’ll sell all my Naglers!”) in Sir William’s f/20 twelve inch mirror that night.

Clear Skies!  ——-  And if you have more than you need, send the surplus in this direction.  😎

Touring the 50mm/60mm Skies, Tour Number Six: Orion’s Belt Stars — Alnitak, Alnilam, and Mintaka

The three stars that gleam and glow and grace Orion’s belt are about as distinct as can be on a cold winter night, or even in the early spring before they start their slide out of sight into the west.

Majestic, fantastic, extraordinary — take your pick of one, or take all of them — Orion is simply in a class all by itself. (Stellarium screen image with labels added, click to enlarge).

Alnitak (Zeta – ζ), at the east edge of the belt, is probably the best known of the three, mainly because it hovers just north of the Horsehead Nebula (lower left center of photo) and southwest of the Flame Nebula (at the left edge of that photograph), even though it does its best to hide both of them behind its 1.85 magnitude blue-white light.  Second best known is Mintaka (Delta – δ), which anchors the west side of the belt at a magnitude of 2.40.  And least known — at least by name — is Alnilam (Epsilon – ε), which is strange since its in the center, and even stranger because it’s the brightest of the three at a magnitude of 1.65, which almost makes it a first magnitude star.

Now the fact that Alnitak is a double (actually a triple) is reasonably well known, and at least as well known is Mintaka’s duplicitous status — but I suspect there are only a few people on the planet that know Alnilam is also a double.  Not a knock-your-socks-off, spin-your-focus-knob dancing pair to be sure, but no less a double despite that.  But don’t let that deceive you — it’s a pretty pleasing challenge for a small aperture scope.  The name is derived from an Arabic word which means “The String of Pearls” — certainly an elegant description of the three Belt Stars.

At any rate, what all of that means is that all three of the Belt Stars are multiple stars!  Which is kind of neat, at least to me.

Now that might produce this kind of reaction  —  🙄  —  but I can explain.  I live on the northwest coast of Oregon.

For the uninitiated, what that means is I spend most of the winter getting drenched by rain and whipped around by wind.  So — when the rain runs dry, and the wind wears itself out, and the first stars return to claim the sky for a whole thirty minutes or so — it doesn’t take a whole lot of stellar electricity to jolt my damp and rusted Star Splitter mind into motion.

But tonight I see a chance to actually spend an entire hour — maybe more if the Sky Gods will look the other way for a while — under the newly rejuvenated sky, and I intend to see just how much I can see of those Belt Stars — and a couple of other gems — with a 50mm and a 60mm refractor.  So follow me — and bring your rain coat, just in case.  (If you haven’t been here before and are curious about the scopes, you might take a look at the introductory piece for this series here.)

I left the labels off this time to avoid cluttering the image with text (these stars are labeled in the image of above), so what you see here, starting on the left (east) side is Alnitak, Alnilam in the center, and Mintaka on the right (west). The brightest of the stars to the south and slightly west of Alnitak is Sigma (σ) Orionis, which is where we’ll eventually end this tour. (Stellarium screen image with labels added, click to enlarge).

Let’s start on the west side and work our way across to the east, which will give us a chance to begin with an easy split, Mintaka.

Mintaka – Delta (δ) Orionis   (Σ I 14)  (H V 10)     HIP: 25930   SAO: 132220
RA: 05h 32.0m   Dec: -00° 18′
Magnitudes:  2.4, 6.8
Separation:   53.0″
Position Angle: 359°   (WDS 2011)
Distance: 916 Light Years
Stellar Classification: BO
Rating: Easy

Greg has already covered the particulars of Mintaka rather well in a DSC-60 post , so I’ll stick mainly with my observations of it in the 50mm and 60mm refractors …………

The secondary is a very sharp pinpoint of bluish light . . . (East & west reversed to match the refractor view, click for a larger look).

………………  and my first observation was how easy this pair is to split.  In fact, it’s so easy that my first view of this pair of stars came several weeks ago in a pair of Canon 10×30 image-stabilized binoculars, and it was a real delight — the secondary was a very sharp pinpoint of bluish light silhouetted against a sky that was more blue than black, thanks to a nearby full moon.

So I could hardly fail with either the 50mmm f/10.8 Zeiss or the 60mm f/13.3 Carton-lensed refractor.  Using a 20mm TV Plössl (27x in the 50mm scope, 40x in the 60mm) in dark skies, the secondary is an intense point of light that seems as if it’s shining through a pin-sized hole poked in a piece of black velvet.  You can’t miss its relatively bright 6.8 magnitudes of light, and it’s far enough away from the glare of the 2.4 magnitude primary that it doesn’t suffer in the least from being overwhelmed.

With all that light available, I decided to give the 7.5mm Celestron Plössl (72x) a chance to perform in the 50mm scope ….. and it responded by etching a beautiful diffraction ring around the primary, and pushing the secondary far enough away that the resulting image looked almost like another pair of stars entirely.

William Herschel was the one to first recognize Mintaka’s duplicitous state, spying it for the first time on October 26th, 1779.  He described the primary as “w.” (white) and the secondary as “bluish” — which matches exactly with what I saw in both scopes, as well as in the binoculars.

Now one of the advantages of the area we’re in right now is you can move from one object to the next without using your finder.  Position Mintaka in the northwest corner of your eyepiece (use a low magnification to insure a large field of view), give your scope a slight nudge to the east, and you’ll be rewarded with the blue-white brilliance of Alnilam as it invades the field of view.

Alnilam – Epsilon (ε) Orionis    (BUP 81)    HIP: 26311     SAO: 132346
RA: 05h 36.2m   Dec: -01° 12′
Magnitudes:  1.7, 10.5
Separation:  179.3″
Position Angle: 58°   (WDS 2011)
Distance: 1342 Light Years
Stellar Classification: BO
Rating:  Difficult

And then see if you can find that sneaky secondary.  It shouldn’t be as tough to find as it is, but part of the problem is the overwhelming brilliance of the 1.7 magnitude primary, and the other part is that the slippery secondary has relatives that look suspiciously similar.  In fact, if I hadn’t looked up their magnitudes, I would swear they’re identical triplets.

Now the first time I looked for the secondary was with the 50mm Zeiss, and I saw what I thought was it right away.  But then I became suspicious — it was too easy.

If you look very closely at the sketch below, you’ll see there are three faint stars lined up at about, or very close, or right at, the correct position angle.  So which one is the secondary?

The magnitudes of the three faint stars to the northeast of the primary, which are discussed here, are shown in the inset at the lower right, and a bonus binary -- Σ 751 -- is visible at the north edge of the field of view. (East & west reversed to match the refractor view, click on the image and you'll lose this caption!).

The magnitudes of the three faint stars to the northeast of the primary are shown in the inset at the lower right, and a bonus binary — Σ 751 — is visible at the north edge of the field of view. (East & west reversed to match the refractor view, click on the image and you’ll lose this caption!).

STScI photo, plotted using Vizier.  East & west reversed to match the sketch above of Alnilam.

STScI photo, plotted using Vizier. East & west reversed to match the sketch above of Alnilam.  Click on the image for a better view.

It’s a heck of a good question, and I racked my mind and my focuser in and out for several weeks — when conditions would permit — in a determinedly ferocious attempt to forge an answer.  One of my many attempts began with looking up the magnitudes of that line of three stars extending to the east of the primary.  From that effort, it looked as if the last of the three, the one labeled 10.5 in the inset of the sketch, was the star I was after.  But I had a sneaking suspicion that one was much too far away, so eventually I discovered I could plot the distance and position angle of the closest of the three stars (the one labeled 11.6 in the inset) using the plotting feature of the Vizier Catalogue Database, and sure enough, that turned out to be the secondary I sought.  You can see the distance plotted in the negative image above (179.3”/60 = 2.99’); the position angle isn’t shown on the chart, but it measured 57.8 degrees.  As for the magnitude discrepancy, the 11.6 magnitude appears to have been the photographic magnitude, and the 10.5 magnitude listed in the WDS is normally the visual magnitude.  (No, photographic and visual magnitudes are not the same, but that’s a story for another day).

Having settled the question of which star was the secondary, there was no question whatever about how difficult it was to see it in both the 50mm and the 60mm scopes — it takes a fiendish delight in fading in and out of the primary’s glare.  What worked best for me was to look directly at the 8.2 magnitude star to its south, which seemed to prompt the secondary to make momentary averted vision appearances.  Stick with the intermediate focal lengths, in this case the 11mm TV Plössl (49x) in the 50mm scope, and the 15mm Plössl (53x) in the 60mm scope.   It takes the diligence and persistence possessed by a more than slightly obsessed Star Splitter to see it — but trust me, you can do it, too!

But hang on a minute!  There’s another double star that’s been sitting very quietly in the field of view all this time, too!

Σ 751          HIP: Not assigned in Simbad    SAO: 132337
RA: 05h 35.8m   Dec: – 00° 59′
Magnitudes: 8.0, 9.0
Separation:  15.8″
Position Angle: 123° (WDS 2003)
Stellar Classification: B8
Rating: Easy

Now these two stars, which can be seen north of Alnilam in the sketch above, aren’t the brightest bulbs in the fixture, but they do have one redeeming feature — you can split them with little effort!  So after that wrestling match with Alnilam, you cam see how that’s a very attractive feature.

You should be able to separate these two at the low magnification the 20mm TV Plössl provides in both of the scopes (27x in the 50mm, 40x in the 60mm), although in the smaller scope it’s possible you might need to jump ahead to something close to the 36x provided by the 15mm Plössl.

But now it’s time to return to the land of the difficult ………………

We’ll follow a familiar procedure  to get there — position Alnilam in the northwest corner of your eyepiece, nudge to the east, and be prepared for the brilliant blue-white light of Alnitak when it invades the field of view from the opposite corner of the eyepiece.

Alnitak – Zeta (ζ) Orionis    (Σ 774)  (H IV 21)     HIP: 26727    SAO: 132444
RA: 05h 40.7m   Dec: -01° 57′
Magnitudes (AC): 1.9, 9.6
Separation:  58.0″
Position Angle: 10°   (WDS 2006)
Distance: 817 Light Years
Stellar Classification: O9.5
Rating:  Difficult in the 60mm; Very Difficult in the 50mm

The secondary is seen here just barely north of the primary. It’s easy to be mislead into thinking one of the fainter stars to the north is the secondary because they’re much easier to see, but they’re much too far away. (East and west reversed once again, click to enlarge).

Alnitak, which was also discovered by Sir William Herschel (on October 10th, 1780), suffers from the same shy syndrome that Alnilam does, but even more so since the secondary, even though almost a full magnitude brighter, is more than three times closer.  And again, it’s easy to be misled by two stars of similar magnitude to Alnitak’s north, one that’s about four arcminutes away with a magnitude of 9.7, and another that’s a bit more than twice that distance with a magnitude of 9.5, as seen in the sketch to the left.

I’ve already covered Alnitak in more detail  with larger apertures, but since we’re dealing here with apertures of fifty and sixty millimeters, there’s considerable more challenge.  To be specific, I can’t claim with certainty that I saw that ghost-like secondary in the 50mm Zeiss, but I may have had a glimpse of it through the 7.5m Celestron Plössl (72x).  I did a bit better in the 60mm f/13.3, catching it with averted vision several times in the 11mm TV Plössl (73x), which tempted me to see what I could do with the 7.5mm Celestron (107x).  But all I saw was the glare glaring back at me, as if to say:  “Not today, go away.”   Honestly, this one just needs more aperture — at least 80mm would be a better choice.

So if we’ve learned anything at all from this struggle with Alnitak and Alnilam, it’s that they offer a pretty good reference point for what the limits are for the 50mm and 60mm scopes we’re using, at least in regard to large magnitude differences.  Alnilam is right at the point where it’s possible to catch sight of the secondary with decent cooperation from the atmosphere, while Alnitak is seriously pushing the limit of what is possible at these small apertures.  Of course, if you’re attempting to pry these two stars apart at a higher and drier altitude than the moisture saturated sea level air I peer through, you could probably extend those limits a bit more.

But, having put you through that one, I’ll see if I can get back into your good graces by taking you for a look at one of the more stunning triple stars in Orion, which is even shadowed by another triple.  And they’re both easy!

Sigma (σ) Orionis (Σ762)         HIP: 26549    SAO: 132406
RA: 05h 38.7m   Dec: -02° 36′
Magnitudes       AB: 3.8    C: 8.8    D:  6.6     E: 6.3
Separation         AB-C: 11.4″          AB-D: 12.8″        AB-E: 41.2″
PA     AB-C:  238°  (WDS 2008)    AB-D:   84°  (WDS 2011)    AB-E:   62°  (WDS 2011)
Distance: 1148 LY
Spectral Classification: O9.5 (A)  B2 (B)
Rating: AB, D, and E — Easy    C: Not Likely

Σ 761          HIP: Not assigned in Simbad    SAO: 132401
RA: 05h 38.6m   Dec: -02° 33′
Magnitudes:         A: 7.9    B: 8.4    C: 8.6
Separation –        AB:  67.8″     AC: 71.8″   BC:  8.5″
Position Angle –  AB: 203°   AC: 209°    BC: 269°  (All WDS 2011 data)
Distance: ?????
Spectral Classification: B5
Rating: Easy, except for the BC split, which is difficult in the 50mm scope

Between Greg and I, we’ve worn a path through the sky to these two groups of stars.  I described my experiences with them in the post on Alnitak mentioned above , and Greg covered Sigma (σ) in a DSC-60 post.  So I didn’t have any problem getting here — I just followed the groove through the sky between Alnitak and Sigma!

But if you don’t see our well worn path, move Alnitak over to the east corner of your eyepiece and then move your scope south slowly and you’ll be rewarded with the appearance of Sigma (σ) on the west side of your field of view.

Sigma (σ) sits in the center of this view, with “D” and “E” seen to its east, and the three stars of the much fainter Σ 761 hover northwest of it. (East & west reversed again, click for a larger and more pleasing view).

And you’ll find yourself looking at a bright 3.8 magnitude primary with a pair of sixth magnitude stars guarding its eastern approach.  Those are the “D” and “E” components, and they’re easily seen in either the 50mm or the 60m scope at low power.  What you won’t see — unless you have very good conditions and a very sharp eye — is the “C” component, which is lost behind the glare of the primary.  That one is difficult to see even in an 80mm scope.  At just a bit less than two magnitudes fainter than “D” and “E”, and almost the same distance from the primary as “D” is, you would expect “C” to be easier to see!   The cause of the difficulty is that the 3.8 magnitude primary is a full one hundred times brighter than “C”, which is a full five magnitudes fainter.  (That figure comes by multiply 2.51 times itself five times).

The much fainter Σ 761 group glimmering northwest of Sigma (σ) in your field of view will show up as a distinct pair of stars at low magnification in both of our small scopes.  I had very little problem splitting the BC pair in the 60mm scope using the 11mm TV Plössl (73x), but it eluded me in the 50mm scope with that eyepiece (49x), and the poor seeing conditions defeated my efforts every time I tried to catch it with the 7.5mm Celestron Plössl (72x).

On a night of very steady seeing, it’s a pure joy to behold those two stars, almost matched in magnitude, sitting there in the black sky so close together you could barely force a photon between them.  They have a very delicate, bead-like quality in a fifty or sixty millimeter scope that is unlike anything seen in larger apertures.  And that deliciously delicate quality is one of the frequent charms of these small scopes.

So there you have it — a diagonal trip through the center of Orion, with a dazzling flourish of multiple starlight to top it off.

Next destination — who knows?  But stay tuned for a surprise or two   ……….    and Clear Skies!

Touring the 50mm/60mm Skies — Tour Number Five: Iota (ι) Orionis and it’s Jewels: Σ 745, Σ 747 and Σ 754

Majestically huge and one of the finest sights in the sky to grace the eye, Orion is absolutely captivating on a dark, moonless night — and even on a full moon night it’s distinctive outline is guaranteed to capture your attention. (Stellarium screen image with labels added, click for a larger view).

If ever there was an area of the sky just calling out to a telescope of small aperture to come and take a long look at it, the area surrounding Iota (ι) Orionis would be it.  And if ever there was an area that is frequently over-shadowed by more spectacular sights, this is it as well.

Well beyond the power of words to do justice to it, M42 has kept me glued to the eyepiece of a telescope for more hours than I can count. It and the diamond-like stars of the Trapezium draw my attention in the same way a bar of steel becomes riveted to a magnet. (Stellarium screen image with labels added, click to enlarge).

The problem is M42, the Orion Nebula.   It’s a spectacular problem, actually  —  because it’s an awe-inspiring sight.  But it’s that very quality which draws your eyes away from the beauty of the area just barely south of it, which under less competitive circumstances would rank right up there with the grandest views in the night sky.

In fact, if you can free yourself from the magnetic attraction of M42, you’ll find Iota (ι) can even be a bit of a problem as well.  On a dark night, it sits at the center of a cloud of glowing nebulosity which tends to divert your attention away from the gleaming jewels surrounding it.  My eyes have inched over to Iota more than once, and yet I’ve never taken the time to identify any of those stars —  nor did I realize how many of them were multiple stars.

But all that’s about to change as of tonight!

Grab your 50mm or 60mm scope and come along with me.  (The introductory material for this series, including the scopes being used, can be found here).  I’ll show you three very easy doubles — one of which is a tantalizingly tough triple and one a ghost-like triple — plus a genuinely difficult double.  And all of them fit very gracefully within the field of view of a small telescope, even at moderate magnification.

Let’s start with two views of the area.  This first one is the conventional view — although the one shown here goes a bit deeper, the orientation matches what you’ll see in an 8×50 correct image finder:

The three multiple-star jewels that surround Iota (ι) are seen here just to its south and southwest. If you happen to have a pair of binoculars, Σ 747 is easy to split. And if the binoculars happen to be mounted, you may even be able to pry apart Σ 745. In fact, the binocular view of this entire area of Orion is a stunning sight! (Stellarium screen image with labels added, click for a larger view).

Here it is again — and this time the view has been flipped horizontally (east and west reversed) to match what you’ll see in a refractor or SCT using a diagonal . . .

. . . and you can see that all four of our stars for this tour fit very comfortably into the field of view of the yellow circle, which is about one full degree in diameter. (Stellarium screen image, click to enlarge the view).

Na’ir al Saif: The Bright One in the Sword

Iota (ι) Orionis  (Σ 752)  (H III 12)      HIP: 26241    SAO: 132323
RA: 05h 35.4m   Dec: -05° 55′
Magnitudes    AB: 2.9, 7.0       AC: 2.9, 9.7
Separation     AB: 10.8″           AC: 49.4″
Position Angles    AB: 138°  (WDS 2009)     AC: 103°  (WDS 2002)
Distance:  1326 Light Years
Spectral Classification   A: O9   B: B   C: A or F
Rating   AB: easy to moderate     AC: difficult

If you look up at Orion on a crisp winter night, your eyes will quickly be drawn to the glow of this brightest star in the sword (although, as I mentioned above, it’s M42 that gets all the attention in a telescope).  That naked-eye brightness is helped more than a little by the cluster of stars surrounding Iota (ι), as well as by the nebulosity it illuminates so skillfully — all of which goes by the collective name of NGC 1980.

Iota (ι) consists of four stars, one of which is a spectroscopic binary — meaning it’s well beyond our reach, whether we’re wielding a 60mm scope or a 60 inch scope.  But it was Sir William Herschel who first dissected Iota (ι) — on October 7th, 1779 — into the three stars we see in our telescopes.  Of those three, the primary is a bright blue-white 2.9 magnitude star which does its absolute best to obscure the other two.  The seventh magnitude secondary is really not all that difficult, but you’ll probably need to use averted vision in a 50mm or 60mm scope to see it the first time you look for it.  If you happen to catch it on a night when the seeing and transparency decide to work together, producing both stable seeing (a III on this chart) and matching transparency, you should be able to see it with direct vision.  In the 50mm Zeiss, I need the 15mm TV Plössl (36x) to see it at all (direct vision) — the 20mm (27x) just wouldn’t pull it out of Iota’s glare — while in the 60mm f/13.3 refractor, the 20mm (40x) is more than enough to do the trick.

The third star (“C”), even though almost five times farther from the primary than the secondary, is 2.7 magnitudes fainter, which is just enough make it a star with a difficult personality.  I can glimpse it with averted vision in the 50mm Zeiss at 49x using the 11mm TV Plössl, and I’ve glimpsed it a few times in the 60mm f/13.3 using a 20mm TV Plössl (40x).  Low power is best here — too much magnification amplifies both the glow of the nebulosity and the glare of Iota (ι).

This is what you’ll see in a 60mm f/13.3 (800mm focal length) refractor at 40x. All of the stars’ companions mentioned in this post are shown here, but some are pretty darn faint. You’ll find it may help to see all of them if you turn off any lights that are near your computer screen. This same sketch, minus the labels, is at the end of this piece. (East & west reversed, click to lose this caption).

And here’s a tip — your focus needs to be very precise!  Focusing until the Iota (ι) primary is sharp won’t necessarily pull either of the two companions out of its glare.  If Iota is pinpoint sharp and the secondary still isn’t visible, nudge your focuser just a bit more and you should see the secondary appear first — what you’ll see is a very tiny gleaming point of light.  When you have it, fine-tune the focus until it’s at its most distinct, and then cast an averted glance a bit beyond it and away from the primary.  That’s the point at which “C” should show up — if it doesn’t, let your eyes wander around the area without drifting very far from the primary.  That 9.7 magnitude micro-dot of light is prone to popping into view and then disappearing again, so be patient.  It’s sly, but not bashful.

Now I’ve never seen Iota (ι) as anything other than blue-white, and the two fainter companions I would characterize as fainter flavors of the same tone.  Haas describes the primary as yellow-white, and Admiral Smyth calls it white.  He saw the secondary as blue-white, and described the third star as — hang onto your focus knob now — grape red.  Sir William Herschel, who saw the primary as white, described both “B” and “C” as “dusky r.[red].”   And the other day I noticed that the Night Sky Observer’s Guide (scroll down to the fourth listing) also describes “C”as red!  So there must be more there than has met my eyes so far.  I think I hear “C” calling out for more aperture.

And Now the Jewels ………………..

Σ 747  (H III 14)          HIP: 26199    SAO: 132301
RA: 05h 35.0m   Dec: -06° 00′
Magnitudes: 4.7, 5.5
Separation:  36.0″
Position Angle: 224°  (WDS 2010)
Distance: 1864 Light Years
Spectral Classification: B0.5, B1
Rating: Easy

Just to the southwest of Iota (ι) is a very distinctive pair of stars of almost equal magnitude, which also make a very attractive pair in binoculars.  Because they’re wide and bright, there’s nothing difficult at all here.  Sir William Herschel discovered this pair on the same night he made Iota (ι) famous, which is where the designation H III 14 comes from.

Again, I see blue-white when I look at these two stars, but F.G.W. Struve, whose name now is attached to them, described the primary as whitish-yellow and the secondary as “bluish” when he looked at them back in 1825.

Wide field, low magnification works best here, especially since it keeps them in the same field with Iota (ι), as well as with our next star …………..

Σ 745  (H III 13)             HIP: Not assigned in Simbad    SAO: 132289
RA: 05h 34.8m   Dec: -06° 00
Magnitudes   AB: 8.3, 8.6      AC: 8.3, 10.4
Separation    AB: 28.6″          AC: 96.9″
Position Angles    AB: 347°  (WDS 2002)     AC: 304°  (WDS 2000)
Distance: 279 Light Years
Spectral Classification: A
Rating   AB: Easy   BC: Moderate

………… which is barely west of it.

You’ll see that the primary and secondary of this pair are almost matched in magnitude, and about the same distance apart as Iota “A” and “B”.  Still, in a small apertured scope, despite the almost equal magnitudes, the secondary has an eerie, ghostly quality about it.  You shouldn’t have any trouble separating the two stars on a night of average to even sub-average seeing (a II on this chart), but if you can’t quite get them with the equivalent of a 20mm eyepiece (27x in my f/10.8 50mm and 40x in my f/13.3 60mm), try something in the neighborhood of a 15mm eyepiece (36x and 53x, respectively). There’s not a lot of light here, so at the 50mm and/or 60mm apertures we’re working with, too much magnification will dim the stars to the point that they become harder to see.

And speaking of a ghostly presence, that describes 10.4 magnitude “C” right down to its last photon.  In the 50mm Zeiss/20mm TV Plössl (27x) combination, I can’t see it at all.  But it suddenly springs into averted vision view as soon as I increase the magnification to 36x with the 15mm Plössl, and it’s almost to the point of being detectable with direct vision in the 11mm TV Plössl (49x).  The 60m f/13.3 sees it with little problem, although I did have to look closely, which shows just how much difference ten millimeters of aperture can make under the right circumstances.

There seems to be some confusion about identity in the Herschel Double Star Catalog, which applies the H III 13 designation to our next star (Σ 754), but it certainly looks to me as though it was meant for Σ 745.  William Herschel looked at it on the same date as our previous stars, and combined it with a description of the star we just looked at, Σ 747.

Here’s his description (from the preceding link), with my comments in brackets:

Double-Treble. It is the preceding or smallest of the two iota’s {confusing, but Herschel tended to group nearby stars with a brighter star in other cases, too, as when he applied Epsilon to H III 111 (Σ 758), a multiple star just north of the middle belt star in Orion (Alnilam), which is the actual Epsilon Orionis}.  The preceding set (forming a triangle) consists of three equal stars {which describes Σ 745 very well — “preceding” refers to their movement through they eyepiece}. All dusky r. The following set (forming an arch) consists of three stars of different sizes. The middle star is the largest; that to the south is also pretty large; and the third is very small. L. w.; l. w.; S. pale r.”  {And that describes Σ 747 well if you include the faint star to its north, which also explains Herschel’s “double-treble” at the beginning of this description}.

Thomas Lewis also assigns Herschel’s H III 13 designation to Σ 745 in his 1906 compilation of Struve’s observations on page 152 of this book.  Whatever the case, F.G.W. Struve again is credited with them based on his 1831 observations of them.

Σ 754  (H III 13)             HIP: 26345    SAO: 132359
RA: 05h 36.6m   Dec: -06° 04′
Magnitudes: 5.7, 9.3
Separation: 5.3″
Position Angle: 288°  (WDS 2002)
Distance: 1919 Light Years
Spectral Classification: B1
Rating: Difficult

And that brings us to our last, and most difficult pair.  Raise a few eyepieces to the Sky Gods and say nice things to them   …………   ’cause you’re going to need some help here!  I’ve spent more time pursuing these diminutive dancing points of light than I’ll ever admit in public, but that’s only because I know they’re well within reach of at least the 60mm scope.  The element that has been lacking is good seeing that happens to coincide with a moonless night.

As it is, I’m fairly certain I glimpsed the 9.3 secondary in the 60mm f/13.3 with a 15mm TV Plössl (53x), but I’m not about to bet the farm — or a telescope — on it yet.  I admit to cheating a bit, however.  First I spied the little dancing devil in a 102mm Celestron f/10 refractor, which in itself was far from an easy task.  But once I had it’s location firmly fixed, I went back to it with the 60mm scope and came away at least 50% convinced I had seen it dance into view briefly.  Then again, a cold, desperate, and determined Star Splitting mind is apt to play tricks, too.

The best I can say for the 50mm scope is I can detect a hint of duplicity — meaning the primary won’t quite come to a sharp focus — at 49x with the 11mm Plössl.  The 7.5mm Celestron Plössl (72x) just about exhausts all the light available, but given very stable seeing conditions, it might be possible to catch the secondary clinging to the primary.

The very stable seeing conditions I need in order to pry this pair apart have been missing for the last eight weeks or so — seems they flew south for the winter.  So I’ll leave it here for now, but I’ll be back to update this entry just as soon the Sky Gods see fit to cooperate some evening — hopefully before April, when I’ll lose Orion to the ravenous Hemlocks which devour all stars at my location that edge too far to the west.

F.G. W. Struve was kind enough in his 1830 observation of these two close stars to leave us at least a description of colors: white and blue.  That matches up with their stellar classifications, and pretty well describes what I saw, even though my apparent glancing glimpse of the secondary was very brief.

Before you leave this area, take some time to slide your scope north a couple of degrees and look closely at the Trapezium in the center of M42, which Greg has already covered very well with a small scope in this piece.  You won’t get the stunning diamond-studded view that can be seen in apertures of four inches or more, but there’s something very addicting about the way those four stars are displayed in a 50mm or 60mm scope as a very tight knot.  The dimmest of the four has a way of fading in and out of view, offering a tantalizing challenge that’s easy to meet with a bit of close scrutiny.

And so another exciting adventure of Touring the 50mm/60mm Skies comes to a rousing conclusion.  If you’ve followed all of these tours, you should be leaning by now toward the realization that there really are quite a lot of double stars up there that are more than willing to meet with small aperture telescopes on a dark night.  And so far we’ve barely scratched the surface — or in this case — the sky.

Next time out we’ll take a stroll through the northern half of Orion.  Until then, may your skies be clear and dark and all the stars intense pinpoints of gleaming light!  😯

Same sketch as above, minus the labels! (Click to see it without this caption).

Touring the 50mm/60mm Skies, Tour Number Four: In the Northwest Corner of Taurus — Σ I 7, Σ 401, OΣΣ 38, and Σ 427

High in the sky, tucked between the Pleiades and the southern border of Perseus, in a visually barren, triangular shaped corner of the sky where eyes seldom pry, is a group of four double stars that have been waiting patiently for a few Star Splitting enthusiasts, such as you and I, to re-discover them.

Which is why we’re out here cooling our toes tonight in the brisk winter air.  And we’re going to rediscover them with a pair of small-apertured refractors — the first being a 60mm f/13.3, and the other a 50mm f/10.8, both of which are described in the introductory post for this series.

So how in the heck did we ever end up here in this barren stellar desert?  A darned good question.

First, immediate credit goes to a dedicated Star Splitter who frequently aims a six inch Celestron refractor into his New Jersey skies.  It was Javier who stoked the stellar flames of my curiosity when he called my attention to this area about a month ago.  Second, when I checked Sissy Haas’s book to see if she had spent time up here, I discovered she had looked at three of the four stars with a 60mm refractor, which stoked those stellar flames into a raging fire.  That’s because — and this is third — the first and second just happened to coincide with the time I was planning this series.

So  —-  I suppose you could say the stars happened to be aligned just right. 😉

Grab your 50mm or 60mm scope and prepare to turn it towards Taurus, and we’ll let the four stars of this tour demonstrate just how capable an instrument a small refractor is. We’re head for this North Taurus Triangle, the corners of which are marked by Omicron (ο) Persei, HIP 15549, and the Pleiades. (Stellarium screen image with labels added, click to enlarge).

Now, by way of preparing you for what will soon be obvious, I need to emphasize one thing here first — these aren’t bright stars.  They’re not particularly difficult — one of them is separated by enough space to chase the Taurus bull through (or for him to chase you through) — but they aren’t bright.  And that means you won’t find yourself dazzled by an enormous flood of photons.  Instead, this tour that will provide an opportunity to enhance your appreciation of those aspects of viewing that are sometimes lost in the glare of those flooding photons.   Because there’s another aspect of double stars that — if you keep at this long enough — can be every bit as aesthetically pleasing as the more visually stimulating sights.

This is a closer view of the area within the triangle …………. (Stellarium screen image with labels added, click to enlarge).

…………. and here it is again, without the green triangle super-imposed on the sky. (Stellarium screen image once more, with labels added).

We’re going to begin with Σ I 7 and Σ 401, which appear as one star to the naked eye (the other two stars of this tour are below the naked eye threshold), and it turns out that the easiest way to get there is to go completely around the triangle.  So, using the chart above that works best for you, we’ll start at the Pleiades (found at the bottom center of either chart), which is the first corner of our triangle.

Then look north about four degrees and locate 2.8 magnitude Zeta (ζ) Persei and 3.9 magnitude Omicron (ο) Persei.  From Omicron (ο), the second corner of the triangle, extend a line about three degrees to the southwest and you’ll find your eyes drawn to 4.5 magnitude HIP 15549, the third corner.  Now extend a line from it to the Pleiades, and not quite halfway along that line you’ll see a faint star, which is the fifth magnitude glow of the combined light from Σ I 7 and Σ 401.

If you can’t see it because of sky glow, point your scope at that halfway spot and chances are you’ll land right on it — I’ve actually done it twice in a row!  Binoculars will help also, so don’t hesitate to use them if you have them.

Σ I 7  (STFA 7)  (HJL 49)          HIP: 16386    SAO: 75964
RA: 3h 31.1m   Dec: +27° 44′
Magnitudes: 7.4, 7.8
Separation:  43.9″
Position Angle: 234°   (WDS 2010)
Distance: 311 Light Years
Spectral Classification: B9
Rating: Easy

Σ 401  (STF 401)  (BC is SHY 445)         HIP: 16411    SAO: 75970
RA: 3h 31.3m  Dec: +27° 34′
Magnitudes  AB: 6.6, 6.9     BC: 6.9, 10.9
Separation   AB: 11.4″         BC: 999.9″
Position Angle   AB: 270°  (WDS 2010)   BC: 129°   (WDS 1997)
Distance: 776.5 Light Years
Spectral Classification   A: A2    B: A3     C: F5
Rating   AB: Moderate     AC: Moderate to Difficult

Now these two stars were a revelation to me when I first laid star prying eyes on them in the 60mm scope  —  mainly because I found them without seeing them.  There was some hazy moisture in the air that night, which meant I couldn’t quite glimpse this pair via the naked eye approach, so I estimated their location, found what looked like it might be the wider of the pair, Σ I 7, in the 6×30 finder, bent over the 20mm TV Plössl (40x) — and darned if both of them weren’t in the field of view.  Admiral Smyth, who had a demonstrated talent for it, would have been proud of the results of my celestial navigation.

Well separated in a dim field, these two stars offer a contrast in spacing and position angle. Haas describes them as a “lovely double double” — and I don’t disagree in the least! (East & west reversed to match the refractor view, click to see a view without this caption).

My eyes were drawn first to the wider Σ I 7, which is also the dimmer of this pair.  But they quickly found their way to the brighter and tighter Σ 401, although they had to stare hard for a few seconds before I realized they were looking at two tightly spaced stars instead of one.  Once their dual nature became apparent, I had no problem keeping the 6.6 magnitude primary and the 6.9 magnitude secondary separated.  But when I returned later on a night with rather poor seeing, I found the two of them merging and parting in a very eerie ir-rhythmic dance.

In the 50mm Zeiss on that first night, Σ I 7 was certainly no problem in the 15mm TV Plössl (36x).  It’s more tightly spaced partner, Σ 401, required a steady eye, but its two gleaming, very closely spaced stellar pinpoints of light were a real delight to behold.  Even with the 20mm TV Plössl, weakly magnified at 27x, Σ 401 was still distinctly separated.

The “C” component of Σ 401 poked its way into view in the 60mm refractor without a struggle, even using the 20mm Plössl, but it took some persistent peering in the 50mm Zeiss to prod it out of the dark sky.   I got it, though, with the 15mm Plössl, thanks to the fact that the 60mm had already shown me where it was.  It’s hardly stunning, to say the least, but it’s not all that tough to find since it lies on a line that runs almost directly through Σ 401 and Σ I 7.

Haas describes these as “a wide white pair (Σ I 7) and a close yellow pair (Σ 401)”, but the closest I could come to finding any color in either the 50mm or the 60mm scope was pale white in Σ I 7 and bright white in Σ 401.  I did get a chance to look at these in a 102mm Celestron refractor a few nights later, but the seeing and transparency were both so poor I still couldn’t detect any color.

Next, let’s wander east to our third star, OΣΣ 38, and we’ll use a new chart to zoom into this area:

To get to OΣΣ 38, move east right between 7.35 magnitude HIP 16791 and the 8.1 magnitude star just north and slightly west of it, for a distance of about two degrees. You shouldn’t have to move very far at all before it appears at the east edge of your eyepiece field. You’ll see it as a pair of closely spaced stars in a 6×30 or 8×50 finder, and it’s easily separated in a small pair of binoculars as well. (Stellarium screen image, click for a larger view).

OΣΣ 38  (STTA 38)              HIP: 17470    SAO: 76122
RA: 3h 44.6m   Dec: +27° 54′
Magnitudes: 6.8, 6.9
Separation:  133.8″
Position Angle: 51°   (WDS 2003)
Distance: 192 Light Years
Spectral Classification: F4
Rating: Easy, Easy, Easy

Nothing difficult here — you’ll see them right away.  As I said earlier, the Taurus bull could race between these almost seventh magnitude stars with no problem.

My first visual encounter with them was in the 50mm Zeiss/20mm TV Plössl (27x) combination, which is the ideal way to see them.  I detected a very slight hint of some  kind of color trying to escape this pair, but I wasn’t sure what it was.  Haas saw “whitish gold” in her 60mm at 25x, so maybe it was a hint of yellow I saw trying to get loose.

Can’t miss these in the center of that dim field! (East & west reversed, click to lose the caption).

As I mentioned, the low power view seems to works best here.  Usually, too much magnification of a widely spaced pair of stars weakens their visual impact.  But in this case  ………….  we’ll see that it reveals another quality lying dormant within the field of view.

As you’ll quickly recognize, the background stars in the field of view here are on the dim side, which is consistent with the general them of this triangular slice of Taurian sky.  But if you look closely, the two main attractions of that field are surrounded by a very distinctive — and dim — cluster of five stars.  The trick to teasing them away from their shy disposition is to add a little magnification and a bit of aperture.  So I gave the 60mm f/13.3 a try, with the 15mm TV Plössl (53x) to tempt them out of hiding, and it did wonders for their appearance, as shown in this sketch:

With a bit more magnification and a 10mm increase in aperture, the surrounding field comes to life and provides an interesting backdrop for the two stars that brought us here in the first place. (East & west reversed once again, click for a caption-less view).

Now no doubt you could do even better with a larger aperture, but we’ve done just fine here with a 60mm scope.

This is one of the subtle aspects of double star gazing I was referring to at the beginning of this post.  It’s no secret that two relatively dim, evenly matched, widely separated stars can be a bit boring.  But the context — in this case, the surrounding field of view — can make all the difference in the world between boring and interesting.  And the main thing with regard to the view we’re looking at right now is to recognize that it has the potential to get even better the second or third time you come back to it.

What seems to happen is this:

Somehow that visual image gets imprinted in the dark depths of your memory in such a way that you’re not the least bit aware of it — until you come back for another look.  And when you do, all of a sudden the light bulb of recognition gets switched on, and you begin to find something not quite describable, yet still very compelling, about seeing that same view once more.  So on one of those visits, maybe about the third time, you find yourself lingering over the eyepiece for several minutes, and gradually you realize the noisy cares of this terrestrial world have been banished from your thoughts.

Trust me, it happens.  It may not be this star that creates that magic, but if you keep at this pursuit, sooner or later that uncanny magic will reach out and grab you one night.

And after that night, the skies will never quite be the same for you again.

Meanwhile, back at the tour center, we’ll start on our way to our last star, Σ 427.  This is the pair that Haas didn’t view with a 60mm refractor (she used a 125mm scope), so we just might be blazing a new trail across the sky with both the 50mm and the 60mm apertures!

Looking again at our last chart, you’ll find Σ 427 lies a very short two degrees to the northwest of our current location at OΣΣ 38.  In fact, it’s probably right at the edge of the field of view in your eyepiece, so just nudge your telescope a bit to the northwest.  If it’s not already there, you’ll see 6.85 magnitude HIP 17220 come into view first, and immediately after that, the two stars of Σ 427 will grace your eyepiece.

Σ 427  (STF 427)  (H N 23)           HIP: 17168    SAO: 76071
RA: 3h 40.6m   Dec: +28° 46′
Magnitudes: 7.4, 7.8
Separation:  7.0″
Position Angle: 208°   (WDS 2007)
Distance: 502 Light Years
Spectral Classification: A1, A2
Rating: Moderate

Or at least they should.

The first time I cast eyes on Σ 427, I could see each of the components very distinctly in the 60mm f/13.3 using the 20mm TV Plössl (40x).  They were a pale white pair, very close, but very clearly separated  ……….  and then the seeing quickly slipped down the scale to about a I, and the two stars became an indistinguishable, slightly elongated blob of light.  I repeated that experience with the 50mm Zeiss, using both the 20mm TV Plössl (27x) and its 15mm sibling (36x) — tight, but not difficult — until the seeing threw up its hands and surrendered to bad influences.

So if your seeing conditions don’t match the III (average) on this scale, you may not get the two-star-view.  I took that into account by rating it as moderately difficult.  Otherwise, the pair will be tight, but quite distinct.

This is really a pleasing pair for the eyes, contrasting well with the previous star, the much wider OΣΣ 38.  Few sights in the sky can compete with a very closely spaced, but still very clearly separated, pair of equal magnitude stars.  I’ve seen similar pairs as faint as 11th magnitude in larger scopes, and they all have an ethereal beauty that is unlike anything else in the starry firmament — NOT better, but unique.

And there they sit, all alone except for each other, right at the center of the view. But wait! Feast your eyes on that pleasing parallelogram in the southeast corner of your eyepiece! (East & west reversed once more, click to see the parallelogram without this caption).

And  ……… ………  if you look closely at the sketch, you’ll see that Σ 427 holds down the northwest corner of a well-shaped parallelogram.  It’s almost easy to miss because it’s off to one side of the field of view, as opposed to being at the center of it.  But that adds to the stellar context once again, and provides another attractive element to this view, one that just might whisper to you some dark night to make a return visit.

The only other scope I’ve used to look at this star was a 102mm refractor in very poor seeing conditions, but that parallelogram configuration held up well in it — so it has possibilities.

And thanks to the whim of celestial happenstance, two more of those stars that compose that parallelogram are doubles.  Both are beyond the reach of the small scopes we’re using tonight, but in the event you come back to this area with more aperture, here’s the basic info.  The one at the southeast corner, Σ 429, is the widest and brightest.  Its magnitudes are 9.3 and 11.8, separated by 16.7″ at a position angle of 105 degrees (WDS 2000).  HO 323 holds down the south corner, and has magnitudes of 8.3 and 13.8, which are separated by a much tighter 6.8″ at a PA of 211 degrees (WDS 1994).  That one will require at least a six inch refractor or an eight inch SCT, good seeing, and probably a minimum of average transparency.

I’ve got both of ’em on my six inch refractor list — along with that almost perfect parallelogram.


I hope you got a little something different from this tour than from the previous three.  Those tours were aimed at more visually stimulating stars for the most part, as well as a few difficult ones to challenge your observing skills.  This group of four, on the other hand, offers a window into the subtle aspects of double star viewing that frequently don’t get noticed because your attention is drawn to the more stunning qualities of the brighter stars.

Both kinds of observing are two sides of the same coin, but it takes time for the subtle side to ripen and reach maturity.  Once that begins to happen, you may find you prefer the more visually stimulating views on one night, and on others, you’ll hear the quiet, but persistent, call of the more subtle sights as they percolate upwards into your conscious thoughts.  More than likely you’ll find the two types of views are complementary, so you’ll switch back and forth on the same night.

And after you develop an awareness of and an appreciation for those subtle aspects of this stellar endeavor, the way you look at the brighter pairs will begin to change.   One night, as a pair of glowing globes illuminates all the glass in your eyepiece with their energetic blue-white photons, it will dawn on you that you’re experiencing an aesthetic thrill that wasn’t there before.

I find that happens now practically every time I turn a focus knob and see Castor — or Algieba, or Rasalgethi, or Meissa, or any one of countless others — come into sharp focus as separate and distinct spheres of pulsing light.  In one case it will be the color that will compete for my aesthetic attention, in another it will be a faint secondary nestled up closely to a brighter primary, or it might be the way a scattering of faint and bright stars are etched sharply into the dark sky.  It might even be the background itself — or it could just be that those globes of light are so distinct and perfectly shaped I can’t pull my eyes away from them.

Or it might be each one of those qualities, following rapidly one after the other, like dominoes cascading in a wave across a table.

Or it might be all of them at once  ——-  overwhelmingly all at once.

There’s nothing like it.


Before you leave this area, it would be a crime of astronomical proportions if you didn’t frame the Pleiades in a wide field eyepiece at low magnification.  There are half a dozen doubles shown in the photo available at that link, which comes from this piece Greg wrote a few weeks ago.  You’ll find enough there to keep you occupied for the better part of an evening.  I can’t help but wonder if the reason for the barren character of the triangle we just left is because all of the stars in this general area have been captured by the Pleiades!

Anyway, it’s a stunning sight — don’t neglect it!

Next time out, I think we’ll work our way through Orion and look at a mixture of both types of stars.  In fact, I suspect we’ll be in Orion for at least two tours.  Right now, though, I’m in a holding pattern until the infernal rain and wind wear themselves out — and if that doesn’t happen soon, I’m gonna have to buy a ticket for a ride on that ark being built by my neighbor at the end of the street.

May your skies be Clear, Dark, and Dry!   Tour Number Five starts   …………..   HERE!