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 right 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)
RA: 05h 32.0m   Dec: -00° 18′
Magnitudes:  2.4, 6.8
Separation:   52.8″
Position Angle: 359°   (WDS 2008)
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)
RA: 05h 36.2m   Dec: -01° 12′
Magnitudes:  1.7, 10.5
Separation:  180.0″
Position Angle: 58°   (WDS 2000)
Distance: 1342 Light Years
Stellar Classification: BO
Rating: Moderate to 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!).

Well, that’s a heck of a good question.  And I’ve racked my mind and my focuser in and out for the last two weeks — when conditions would permit — and I’m still not sure.

Here’s the problem: MegaStar, which I usually consult in cases like this, shows the inner star to be at the correct distance, but it puts the magnitude of that star at 11.6  — and that one is very hard to see at the apertures we’re using.

So I did some comparing of distances by going back to Mintaka.  Using a four inch scope, I centered the primary and ran the magnification up to 200x.  That put Mintaka’s secondary halfway to the edge of the field.    It sits at a distance of 52.8″ from the primary, which is a little less than one third of of the 180.0″ that separates the Alnilam primary and secondary.

So then I swiveled the four inch scope over to Alnilam, centered it, and found the 11.6 magnitude star, the one that is closest to the primary, was just a little bit more than halfway to the edge of the field — in other words, a bit beyond the 52.8″ separating the Mintaka pair.  Then I moved the primary halfway to the south edge of the eyepiece, which brought the second star — the one that is shown with a magnitude of 11.0 in the sketch — into view at the upper edge of the field — and that corresponds to about three times the distance separating the two Mintaka stars.  So based on that observation, that’s the one we want.

But hang onto your focus knob a minute — MegaStar assigns the third star, the one that is farthest from the primary, a magnitude of 10.5 (the same magnitude assigned to the secondary in the WDS) — and it also shows it at a distance of about six arcminutes from the primary, which is twice as far as the 180.0″ (or three arcminutes) that is shown for the secondary in the WDS.  So it looks as though MegaStar has the magnitudes mixed up.

Then I turned to my backup in cases like this, Sky Safari, and it doesn’t show any of the three stars in the field!

Holy perplexing Plössls — what’s a curious Star Splitter to do?!!!!!!

At this point, I’m of the opinion that the second star (the middle of the three) is the secret secondary, the same one that MegaStar says is an 11.0 magnitude star.  And for now, I’ll presume the magnitudes it has assigned to the the two outer stars are the reverse of what they’re supposed to be.  In the meantime, I’ve ordered an eyepiece with a cross-hatched illuminated reticle that will allow me to judge relative distances between stars, and I’ll take another look just to make sure I have the distances correct.  And I’ll be back with an update.

That 11.0 magnitude star (the supposed secondary) can be tough to see in both the 50mm and the 60mm scopes — it takes a fiendish delight in fading in and out of view.  What worked best for me was to look directly at the 8.2 magnitude star to its south, which seemed to prompt the 11.0 magnitude star 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
RA: 05h 35.8m   Dec: – 00° 59′
Magnitudes: 8.0, 9.0
Separation:  15.8″
Position Angle: 123° (WDS 2003)
Distance:
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)
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 mislead 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)
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
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!

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)
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)
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)
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 if 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
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).

Sigma (σ) can be seen here to the southwest of Beta (β), just above the back of the Queen's chair. (Stellarium screen image with labels added, click for a larger view).

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A beautiful double star on the lady’s left elbow, and one degree south of [NGC 7789], which lies . . . between σ [Sigma] and ρ [Rho].  “A” 6, flushed white; “B” 8, smalt blue; the colours are clear and distinct, though less fine than those of  ε Boötis, of which this is a miniature.”

(Admiral William H. Smyth in The Bedford Catalog, 1986 edition, pp. 541-42)

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The venerable Admiral had a way of describing double stars (and deep sky objects as well) that sometimes leaves you lingering over his words.  In this case, he couldn’t be more correct in his description of Sigma (σ) Cassiopeiae as a “a beautiful double star,” and his colors  –  “flushed white . . . smalt blue“  –  stand the test of time as well.

But I’m not sure what artwork he was gazing at when he placed Sigma (σ) Cass at the Queen’s elbow, or for that matter, on her left side.  Our illustration here favors her right side and shoulder, instead — but that’s not to say the Admiral was in error.  If you look closely, you’ll see north is facing down in the portrayal above — which means if you position north at its usual place at the top of an illustration, you’ve placed the poor Queen on her head.  So in order to uphold the Royal dignity, I rotated the illustration one hundred eighty degrees.  All of which is a long way of saying the Admiral may have been looking at an illustration totally opposite in orientation to the one above.

A lot can happen in the 168 years since he cast his eyes on the Queen.

Different orientation now, with west at the bottom of the chart and east at the top, matching Cassiopeia's position in the January sky at nine to ten in the evening. An easy way to find your way to Sigma (σ) is to imagine a line at Beta (β) running at a ninety degree angle to the one that connects Alpha (α) and Beta (β). Extending that line four degrees to the southwest will put you right in the middle of a tight little cluster of three stars, the brightest of which is Sigma (σ). Rho (ρ) and Tau (τ) can be seen hovering to its northwest, with the open cluster NGC 7789 midway between Sigma (σ) and Rho (ρ). (Stellarium screen image with labels added, click for a larger view)

Sigma (σ) Cassiopeiae (Σ 3049)  (H I V)
RA: 23h 59.0m   Dec: +55° 45′
Magnitudes    AB: 5.0, 7.2        AC: 5.0, 10.4
Separation     AB: 3.1″              AC: 106.2″
Position Angle      AB: 326°  (WDS 2007)     AC: 66°  (WDS 2008)
Distance: 1524 Light Years
Spectral Classification   A:  B1    B: B3
Status    AB:  Possible binary (Haas, Kaler)     AC: Physically unrelated (Kaler)

Now I’ve had Sigma (σ) Cass waiting in the wings since August of this past summer, but could never seem to get back to it for a more detailed look, much less spend some time in the surrounding area to see what else was lurking beyond the reach of my two naked eyes.  In fact, I believe it was Neil English who pointed this one out to me.  I can’t find his description of it now, but I recall him mentioning it formed a pair of exquisite suns in his 80mm f/11 refractor — and resisting a description like that is more than my powers of resistance can resist.

I looked at it that first night Neil mentioned it, did my best to capture its exquisite excellence in a sketch, and then, with the best of intentions, started back to it several times in the following weeks and months  — more times than I can count, actually.  But the heavens are bountiful, and I’m always curious, and other constellations called to me (I’m easily diverted when near a telescope), and, well,   ………….   I just hope the Queen will continue with that Royal pension, and the Admiral will maintain his usual calm disposition, and Neil will keep sending me gems like this one.

But to get back to the Admiral’s description  …………………………
Is Sigma Cass actually “beautiful?”
Does a sloop sail silently on a calm sea?

Is it “flushed white ……. smalt blue “
I had no problem flushing the white out of the primary  ……..
but that blue    ……….   maybe a trace if you look closely.

What I saw was bright white in the primary and pale white in the secondary — and I looked at it half a dozen times.  Haas describes it as “a bright yellow star almost touching a dim ash white” and The Cambridge Double Star Atlas adds this: “Tight pair with intense bluish & greenish tints.” (p. 14)  Jim Kaler describes them as “nicely blue-white”, although he may have been referring to the spectral class, as opposed to a visual observation.

And Sir William Herschel, who discovered this star on August 31st, 1780, described the primary as “w. [white] a little inclining to r. [red]” and the secondary he called “dark,” which in his usage seems to have meant dusky or red.  And he placed it at “the vertex of a telescopic isosceles triangle turned to the south.” (And it is).

So I guess we can say the verdict on color is  ……………  unanimously colorful.

My first view of Sigma (σ) Cass was through a 102mm Celestron f/10 refractor on August 19th (2011).  I approached it first with a 12mm Radian (83x) perched in the C102′s diagonal, and quickly discovered I had to sharpen my visual apparatus considerably in order to see the very close secondary.  It wasn’t that it was all that tough to split, but it required a disciplined application of Star Splitter scrutiny in order to excavate it out of the primary’s fifth magnitude glow.  A step up to a 10mm Radian (100x) separated it distinctly and very pleasingly, allowing me to relax my scrutinous scowl just a notch or two.

Encouraged by the steady appearance of both stars in my normally seeing challenged skies, I called out to the always-ready 7.5mm Celestron Plössl (133x), which leaped from it’s location in the eyepiece box directly into the diagonal.  After landing with a solid chrome clang, it scrunched its squat little self into its comfortably confined new home and went to work.  A few quick turns of the focus knob and I had Sigma (σ) centered and focused, and still with very minimal vibration.  I should have increased the magnification, but I knew that was the view for me, so I captured if for posterity, as you can see below.

"A" 6, flushed white; "B" 8, smalt blue; the colours are clear and distinct, though less fine than those of ε Boötis, of which this is a miniature." (East & west reversed to match the refractorized view, click to see it again without this caption).

The 60mm f/15 keeps the 102mm Celestron company in this rare exposure to daylight. These scopes are really black, but I think they inhaled some of that beautiful blue sky that afternoon. (Click for a larger view)

Mounted on the C102 (and painted in the same sinister black color) is a 60mm f/15 refractor I built, which has slayed many a close double star in the dark of night since I first allowed light into its lens.  It lived up to its reputation that night, coaxing a very delicate, tear inducing hair split from Sigma (σ) at 82x through an 11mm Televue Plössl.  I remember trying to go deeper with the 7.5m Celestron (120x), but finding it lacked the same magical effect produced in the larger scope, I went back to the 11mm eyepiece and let my eyes soak up those two very tight points of white starlight while trying to restrain the tears.

And the 10.4 magnitude “C” component?  It was faintly obvious in both scopes.  At thirty-four times the distance which separates the primary and secondary, it appears it might be along just for the ride.  Discovered in 1879 (not sure by who, but apparently not S. W. Burnham, as I first suspected), it’s generally considered to be unrelated to either of the other two stars.

Those two others, however, are probably a true binary pair.  Kaler conjectures that “A” and “B” are about 1400 astronomical units apart, resulting in an orbital period of something like 14,000 years.  I looked at data going back to 1850 (p. 698 of this book), when the measurements seem to have become more consistent on this pair of stars, and found there appears to have been very little change, if any, in the separation and position angle of the two stars.  That adds some substance to Kaler’s statement that the probable orbital period is too long to allow computation of a probable orbit.

At any rate — take a look at Sigma (σ) Cass the next time you’re poking around in Cassiopeia.  It tends to get neglected I think, partly because Eta (η) Cass gets a lot of well-deserved attention, and also because it isn’t included in the usual zig-zag “M” or “W” asterism that is normally sketched between the constellation’s stars.  And while you’re there, slide your field of view one degree further north and take in the exquisite open cluster beauty of NGC 7789 (discovered by William’s sister, Caroline Herschel), also described admirably well by the Admiral:

A fine galaxy cluster of minute stars, on a ground of star-dust, on the upper part of Cassiopeia’s chair or throne . . .  it lies in mid-distance between ρ and σ, stars of the 5 1/2 and 6 magnitudes, each of which has a companion of the like brilliance.  It is, indeed, a very glorious assemblage, both in extent and richness, having spangly rays of stars which give it a remote resemblance to a crab, the claws reaching the confines of the space in view, under an eyepiece magnifying 185 times.”   (The Bedford Catalog, p. 539)

Clear Skies! 

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UPDATE

I came across the neat little asterism shown in the sketch below a few nights ago — a wide, warped parallelogram with an interestingly shaped and dimmer version near the middle of it.   It’s actually very obvious, but I never really saw it until I backed off for a wide field view and quit riveting my eyes on Sigma (σ).   Details are in the caption and in the comment which follows the photo.  If you look very closely, you can see the Sigma (σ) secondary clinging tightly to the edge of the primary.

For those interested, the magnitude of HIP 118077 is 5.55, HIP 118057 is 6.55, and HIP 118250 is 8.35. Starting at the top of the inner parallelogram and going in the same clock-wise direction, the magnitudes are 9.50, 9.25, 9.60, and 8.40. All of which adds up to a very visible little asterism. (Sketch started from a SkySafari screen image, which provided the colors! Click to lose this caption).

Here’s an excerpt:

The concert hall at the Syndey Opera House holds 2,700 people. This blog was viewed about 20,000 times in 2011. If it were a concert at Sydney Opera House, it would take about 7 sold-out performances for that many people to see it.

Click here to see the complete report.

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)
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
RA: 3h 31.3m  Dec: +27° 34′
Magnitudes  AB: 6.6, 6.9     AC: 6.9, 10.9
Separation   AB: 11.4″         AC: 999.9″
Position Angle   AB: 270°  (WDS 2010)   AC: 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 6x30 or 8x50 finder, and it's easily separated in a small pair of binoculars as well. (Stellarium screen image, click for a larger view).

OΣΣ 38  (STT 38)
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
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.

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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.

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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!

First, though, you need to meet the individual that made this tour possible, the Cephean King:

I do believe that's an old 40mm long focal length refractor the King is holding there in his left hand, and it even looks like the Lacertan Lizard is attempting to get a look into it. And for baseball fans, if you look closely at the constellation's outline which is superimposed on the king, it's remarkable how much it looks like home plate. And it can serve as a pointer to Polaris as well -- if you follow it north, it'll take you ten degrees west of the North Star. (Stellarium screen image with a few labels added and ..... er ...... a few modifications; click for a closer look).

We’re going to start just below the King’s right elbow, where we’ll find Beta (β) Cephei, which was also known as Alfirk back in the days of the Arabian astronomers.  So grab your scope and let’s head out the door!  (If you missed it, the background on the scopes and eyepieces we’re using in this series can be found here).

You'll find 3.2 magnitude Beta (β) Cephei shining somewhere between fairly bright and almost dim in the northwest corner of the slightly warped Cephean square, and we'll meet its partners in duplicity, Xi (ξ) and Delta (δ), as we work diagonally across to its southeast corner. Note that this chart has been rotated ninety degrees to the right in order to match Cepheus' position in the early evening winter sky. (Stellarium screen image with labels added, click to enlarge).

Beta (β) Cephei (Σ 2806)
RA: 21h 28.7m   Dec: +70° 34′
Magnitudes:  3.2, 8.6
Separation:  14.1″
Position Angle:  250°   (WDS 2009)
Distance: 595 Light Years
Spectral Classification: B2, A
Rating: Easy to moderate

Greg first called my attention to Beta (β) about a year and a half ago, and since then I’ve looked at it more times than I can remember.  I’ve always been delighted to have its white light warm the innards of a 60mm refractor, and it was no different this time for the 60mm f/13.3 I’m using for this series.  The temperature was about thirty five degrees on this cool winter evening, with a cold breeze out of the north rattling some dry leaves across the ground under my deck — even the winter weather adapted 50mm Zeiss saluted Beta’s warm white light with a hearty “Vielen Dank!”

I started with low magnification in both scopes — the 20mm Televue Plössl (40x) in the 60mm scope and the 15mm TV Plössl (36x) in the Zeiss 50mm.  Although the two stars are separated by a modest 14.1″, there’s slightly more than five magnitudes of difference between them  — which means you gotta look closely to see the secondary!

I did, and it was clearly there, nestled up snugly to the primary, which looked like the smart thing to do on this cold winter evening.  That secondary is a very tiny, grayish-white gleaming point of light, and considering that it’s a mere 8.6 magnitude collection of photons, it’s surprisingly intense.

Look closely or you'll miss that dim little secondary -- and then be prepared to slip into a primary stupor. (East & west reversed to match the refractor view, click for a larger look).

But it was the primary’s white that wowed me into a stupor.  You have to see this on a moonless night!  As you center it in the eyepiece and bring it into focus, it locks your eyes in its embrace before you even think about resistance.  I’ve mentioned the delicate quality of the 60mm view of Beta (β) in a previous description of it, but there wasn’t anything delicate about this process.  It grabbed me and refused to let go.  Not that I put up a lot of fight, mind you.

The highlight, though, was the hypnotic view created by the combination of the 50mm Zeiss and an 11mm TV Plössl.  Now that’s only a 49x view, but it’s the best 49 x’s I’ve had for quite some time.   I experimented with the 7.5mm Celestron Plössl in both scopes a few times, and since the 50mm/11mm combination kept calling me back, I decided to use it for the accompanying sketch.

Although this is not a difficult pair to pry apart, I’ll throw in a moderately difficult rating for Beta (β), if only because you have to sit up straight and give it your undivided attention in order to see the secondary.  But it’s really not much strain, and it more than rewards the minor effort required.

Not at all a bad start for this third tour!

Now we’ll start our diagonal trek across the center of Cepheus to our next stop, Xi (ξ) Cephei, which also has another name from its Arabian past, Kurhah.

Xi (ξ) Cephei (Σ 2863)
RA: 22h 03.8m   Dec: +64° 38′
Magnitudes: 4.5, 6.4
Separation:  8.0″
Position Angle: 275°   (WDS 2010)
Distance: 102 Light Years
Spectral Classification: A3, F7
Rating: Easy

This is another easy assignment for both scopes tonight, although you’ll discover you do have to look closely once again to distinguish the glow of the secondary.  If you’ve been using larger aperture scopes, and this is your first foray into the night sky with a 50mm or 60mm refractor, one of the things that will strike you immediately is the delicate appearance of the stars.  That delicacy is created by the smaller, tighter appearing points of starlight, but it also requires closer scrutiny when separating closely spaced pairs.  Once you get used to the difference, it’s not at all difficult, and in fact, adds considerably to the aesthetic charm of the view.

As you bring Xi (ξ) into focus, you’ll see it sports a bit of color — unlike Beta (β) — which is very evident even in a 50mm or 60mm lens.

A soft gold primary and a silver-white secondary combine to give Xi (ξ) an elegant distinction. (East & west reversed again, click for a more distinct view).

That color — it’s a pleasantly light gold — was the first thing that captured my attention.  So much so, in fact, that I almost had to force my eyes to search for the secondary, which is about twice as close to the primary as what Beta’s was.  In this case, though, we’re only dealing with a two magnitude difference in brightness, as compared to 5.4 magnitudes of difference between the Beta (β) pair.  To put numbers to it, what that means is Beta “B” is about 150 times fainter than Beta “A”, while the Xi (ξ) secondary is a mere 6 times fainter than its parental primary.  And because it’s brighter, that secondary appears to ours eyes to be noticeably larger than Beta’s secondary — which provides the added benefit of making it easier to pick out of the primarial glow.

One strange thing about that color, though — and star colors are notoriously unpredictable — is that with a classification of A3, the primary should appear white.  And the secondary, classed at F7 (which is almost into the yellow category — see this chart), should be the one that appears to be yellow — but I saw it as white.  I can’t help but wonder whether that secondarial color eked its way over to the primary instead.  Who knows — it’s just as likely to be the reverse the next time I look.  It certainly wouldn’t be the first time!

Don’t hesitate to add some magnification here since both of these stellar lights emit more than enough light to keep your eyepieces illuminated.  I switched back and forth several times in both scopes from the low magnifcation-wide field view offered in the 20mm TV Plössl to the more restricted confines of the 7.5mm Celestron Plössl, but finally found the 20mm (27x) view in the Zeiss to be the most attractive.

That combination provided a luxurious two degree field of black velvet for a backdrop, and it placed the Xi (ξ) pair so close together they were barely apart, yet still clearly separated with distinction.  Adding to the sheer charm of the view was the circular black void that surrounds them.  The nearest clustering of stars bright enough to attract your attention is at the southeast edge of the eyepiece field.

In that sense, Xi (ξ) is in full command of its immediate surroundings — because if you pan around the field a bit, or peek into a 6×30 or 8×50 finder, you’ll find this double delight is actually located in a very rich field of sparkling white diamonds.  Take a look around — it’s a beautiful sector of the galaxy!  It would be a shame to race right past it to Delta (δ) without pausing to explore for a few minutes.

Delta (δ) Cephei  (Σ I 58)
RA: 22h 29.2m   Dec: +58° 25′
Magnitude:  4.2, 6.1
Separation: 40.7″
Position Angle: 191°   (WDS 2010)
Distance: 982 Light Years
Spectral Classification: F5, B7
Rating: Easy

Now if you look again at the chart we’re using, you’ll see Delta (δ) lurking off of the eastern edge of the slightly out of kilter Cephean square.  If you can’t quite see it, extend a line from Xi (ξ) to Zeta (ζ), and then make a ninety degree turn to the east and you’ll land practically on top of it.

Delta (δ) actually deserves a rating of easier than easy.  There’s nothing difficult here — in fact, it rolls over and surrenders its duplicity without the least fight on first sight.  And it’s Albirean beauty is immediately captivating.

If we’ve followed a progression here in level of difficulty from moderately easy to easier than easy, we’ve also followed one of color.  Beta (β) was all white — fantastically white — Xi (ξ) showed us a bit of gold, and Delta (δ) simply steals the show.

Shades of Albireo! Weaker in intensity -- although not by much -- this pair of stars could almost be mistaken for that more famous gold and blue pair in Cygnus. (East & west reversed once again, click to get a better view -- and turn out the lights! It makes a difference!)

Its 4.2 magnitude primary is a glowing little globe of gold-yellow-white light, accompanied at a comfortable distance by a slightly blue secondary of two magnitudes less intensity.  They put on one of the best imitations of Albireo that you’re going to find high over your head.  If you could turn up their brightness levels to match those of Albireo, I would wager a pair of Plössls you would find yourself looking at identical twins.

The wide field view is still the best here, but don’t hesitate to increase the “X” factor.  I saw some of the star color start to fade in the 60mm scope using the 11mm TV Plössl (73x), and also in the 50mm Zeiss loaded with the 7.5mm Celestron Plössl (72x).  But in compensation for the slight loss in color, that little group of three stars just to the west of the Delta (δ) pair emerged in a different light, putting on a display of distinctive character that had me wondering if they might be stellar relatives.  And not surprisingly, that turns out to be the case.  In fact, it’s a triple star, but only two of the three components are visible in the sketch.

This is a complicated star that carries two designations.  What you see in the sketch is the AC pair, designated as ARN 79, with magnitudes of 8.5 and 9.5, separated by 79.2″, with a position angle of 320 degrees (WDS 2008).  What you don’t see is the “B” component, designated as H 4 31 — that secondary has a magnitude of 10.5 and lies 25.3″ from the primary, at a PA of four degrees (WDS 2008).  I’ll un-officially designate them now with another name — the Deltarian Guards — since they seem to be doing just that.  And I’ll add that the AC pair is an easy split in either the 50mm or the 60mm scopes.

What I had originally planned to do next was lead you over to Mu (μ) Cygni, also known as Herschel’s Garnet Star.   No, it’s not a double, but it’s radiates one of the purest, deepest, head-turning shades of deep orange and/or red in the Celestial Sphere.  Sir William obviously saw the color as garnet, and thus the name.  You can find that garnet glow lying about a degree south of and halfway between the line that connects Zeta (ζ) Cephei and Alpha (α) Cephei, as shown in the chart below.  This is a variable star, fluctuating between 3.6 and 5.0, but regardless of what magnitude you happen to catch it at, it’s a beautiful sight in a medium focal length eyepiece — say the 15mm TV Plössl — in the diagonal of a 60mm scope.

But — as I was being enriched with Mu’s dark orange-red photons, my memory circuits re-connected and reminded me there just happens to be a pair of stars lying nearby, one of  which is quite a sight in a 60mm lens.  So we better take a peek — or we’ll both regret it forever.

And it’s not at all hard to get there:

Mu (μ) Cephei sits a degree south of the line joining Alderamin, aka Alpha (α) Cephei, and Zeta (ζ) Cephei. Our next two stars, Σ 2816 and Σ 2819, are enveloped in the reddish glow about another degree to the south, which goes by the name of IC 1396. (Sky Safari screen shot with labels added, click for a larger look).

Σ 2816
RA: 21h 39.0m   Dec: +57 29′
Magnitudes   AC: 5.7, 7.5    AD: 5.7, 7.5
Separations   AC: 11.8″       AD: 20.0″
Position Angles   AC: 120°  AD: 339°    (WDS 2010)
Distance: 1200 Light Years
Spectral Classification: O6
Rating: Easy

Σ 2819
RA: 21h 40.4m   Dec: +57° 35′
Magnitudes:  7.4, 8.6
Separation:  12.7″
Position Angle:  59°   (WDS 2003)
Distance: 245 Light Years
Spectral Classification: F5
Rating: Moderate

Now it’s Σ 2816 that I want to call your attention to — not that I need to, because you’ll find your eyes are drawn to it so quickly you can hear them snap into place.  It’s bright white 5.7 magnitude primary has two evenly matched 7.5 magnitude companions arrayed on either side of it, forming an open “V” pattern, almost like the wings of a bird in flight.

I found the triple impact of Σ 2816 so stunning it took a few minutes to absorb it all. There is a lot to be seen in this one degree field of view. Absorb it slowly -- let time stand still for a while. (East & west reversed, click to get a larger look).

To it’s northeast, you’ll see the 7.4 magnitude primary of Σ 2819, and you’ll have to look closely to catch the 8.6 magnitude hint of its secondary, somewhat obscured by the glow created by the 1.2 magnitudes of difference.

In between these two stars is another close pair which also lays claim to a shared stellar lineage.  That one is STI 2582, which according to the most recent figures in the WDS (2002), has magnitudes of 8.0 and 11.1 separated by by 21.1″ at a position angle of 187 degrees.  I’m rather surprised I captured that faint secondary in the Zeiss 50mm refractor, but the transparency that night was excellent, and it allowed me to go a bit deeper than I would have otherwise.

So in a one degree field of view, we have a beautiful triple star, a somewhat challenging double, and another pair that’s even fainter and more challenging  —-  and all of it well within the reach of lenses of fifty or sixty millimeters in diameter.

And that’s not all!  If you happen to be looking at these two stars on a dark night with good transparency — and your eyes are totally adapted to the darkness — you’ll see thin wisps of nebulosity scattered here and there through the field of view — yes, even in these small apertures .

It’s best seen at low magnification, so stick with the 20mm view in the 60mm scope, and use the 20mm or the 15mm eyepiece in the 50mm scope.  That nebulosity, designated IC 1396, belongs to the red glow which can be seen on the chart shown above.  This area is also considered an open cluster, and again, it’s cluster-ness is best seen at low magnifications.

But for the best view of the Σ 2816/Σ 2819 pair, I found the 15mm Plössl (53x) was my first choice in the 60mm scope, and the 11mm Plössl (49x) came out on top in the 50mm scope.  I started a sketch using the 60mm scope on the same night I made the sketches for the three Cephean stars already described above, but the clouds took command of the sky before I got very far.  So I went back two nights later and used the 50mm Zeiss/11mm TV Plössl combination.

The seeing was poor, poor, poor, and sometimes horrible, horrible, horrible — which meant I found myself adjusting the focus several times to bring out the background stars.  But in the stunning transparency that was at the opposite side of the seeing scale, the nebulosity of IC 1396 really wrestled my attention away from these stars.  In fact, I was thrilled to the tips of my focus fingers with the fact that I could see it so clearly in a 50mm lens.

My advice is to linger here for another hour or so and just scan the sky slowly.  This is a rich section of the Milky Way — start at Mu (μ) Cephei and gradually work your way into the northern Cygnus area and you’ll be amazed at what you can see.  If you can latch onto a leisurely pace, you’ll find yourself looking at more starry clusters than you can count, and immersed so deeply in nebulosity you’ll never find your way back to Mu (μ).  But since we’re done for the night now, go ahead and get lost up here!

And by the time you find your way home, we should be just about ready for the next tour.  For that one we’ll traverse to the opposite side of the cinematic celestial screen and ferret out four new and seldom seen doubles in Taurus.  So don’t disappear — Tour Number Four will soon appear here!

If you haven’t read the introductory post for this series, you might take a look at it here.

So strap yourself in — we’ off again!

Polaris holds down the north tip of the handle of Ursa Minor (Stellarium screen image with labels added)

Polaris
(Alpha [α] Ursa Minoris)
RA: 2h 32m  Dec: +89° 16′
Magnitudes: 2.0, 9.1
Separation: 18.2″
Position Angle: 232°
(WDS 2009)
Dist: 465 Light Years
Spectral Type: F7
Rating: Difficult

So why are we beginning this second tour with a difficult star?  You really  didn’t think this was always  going to be easy, did you?

Seriously, the reason I decided to start this tour with Polaris is because I start every session by looking at it — and since it’s a binary star, we might just as well see what we can see since we’re here already anyway.

If I’m using an equatorial mount, starting with Polaris is a necessity in order to get lined up with celestial north.   On the other hand, if I’m using an alt-az mount, I find it’s still handy to use Polaris in order to make sure my finder is lined up with the scope it’s mounted on.

Why use Polaris for that, you ask?  Because it doesn’t move!

At least not much for quite a while.  Actually,  if you want a real treat, take a look at the position of the secondary at the beginning of your evening, and then look again about four hours later — and you’ll find it’s moved very noticeably.  Really kind of neat — but then I used to listen to corn grow on hot summer nights in Ohio.

(But to be precise here, the motion you see is caused by the earth rotating on its axis, and that in turn is causing Polaris to appear to rotate very slowly around true celestial north, which is located about three quarters of a degree from the star.  Because the secondary is gravitationally attached to Polaris, it goes where Polaris goes — or in this case, seems to go).

And in answer to the question which I know is on the tip of your tongue  ……………….

“How difficult is it to see that beady little 9.1 magnitude secondary?”  …………………..

The definitive answer is  ……………………

Well, it depends.

When the seeing is poor — let’s call it a I or a II on this scale, it usually isn’t visible in a 60mm scope.  Or if the transparency is below average — again a I or a II  (I don’t have a chart to refer to, but it’s equivalent to the seeing chart) — you can forget it.

Otherwise, it’s there to be had, but it will take some judicious use of focusing talent to catch it.  First, look for a very faint, very barely there, pinprick of light.  Second — don’t overdo it on the magnification, or you’ll lose the secondary in the glow of the primary.

On the night I had the two scopes out for this series, the moon was about half full and over in the southeastern corner of the sky.  Despite that, the sky background was dark enough that I could see the secondary in both scopes.  In the 60/800, it was distinct, but faint, using the 20mm TV Plössl (40x).  I tried the 15mm version (53x), but almost lost it in the glare.

This is a pretty darn close match for what you can expect to see at the eyepiece, so look closely! (East & west reversed to match the view in a refractor, click to get better look.)

In the 50mm Zeiss, I could see the secondary — barely — using the 20mm Plössl (27x), but was able to see it a bit more distinctly with the 15mm Plössl (36x) and the 11mm Plössl (51x).  But still, it was just barely there — as in difficult.

The key in both scopes was a precise focus.  When you’re trying to see something this dim, there is a very critical focal point — meaning a very narrow range of focuser travel — at which that photon-challenged pinpoint of light will pop into view.  Go past it — and it’s gone completely.

One technique for prying it out of the dark sky is to bring the primary into sharp focus, then barely nudge the focuser in one direction, remove your focus fingers from the focuser to allow any vibration to settle down, then nudge again, and again, etc., until the secondary’s faint photons emerge.  If the primary starts to go out of focus, then refocus on it and try the other direction.  In other words, you need a more precise focus than can be achieved by focusing on the primary alone.

Another technique that works is to turn the focuser knob until the dimmest stars in the field of view become visible.  Experiment with that and you’ll find there’s a point at which they just begin to come into view — turn the focuser knob a slight bit more and they’ll begin to fade from sight.    Capture that point at which they first come into view, and then the secondary should be visible.  If not, try nudging the focuser just a very  slight amount in either direction.

You have to be patient!  You aren’t going to pry it out of the darkness unless you look long and hard and carefully.  Based on my experience, what will probably happen is that you’ll be staring into the eyepiece one night, and just when you’re about to give up, you’ll suddenly realize you’re looking right at it — which will prompt an outburst of this sort: “It’s really there!”   And it is.

What if you’re under severely light polluted skies?  I don’t have that problem — one of the most unnecessary evils mankind has ever inflicted on itself — so I can only guess.  But my guess is no, you won’t see the secondary.  The nearest experience I can compare it to is my skies under a full moon in the winter when the evil orb is almost directly overhead, bouncing its reflected rays all over the sky.  If — and it’s a BIG if  — the seeing and the transparency are a IV or better, I can usually just catch a glimpse of it.  But that’s only because I know right where to look.

If you don’t get the secondary on your first attempt, don’t give up.  With practice, it will pop right into view in a 60mm lens, and almost certainly when you least expect it.  Remember, you’re looking for a very FAINT, very SMALL, pinprick of light.  Once you’ve seen it the first time, and realize how small and faint it really is, you’ll have very little problem seeing it again.

But — if you didn’t see it this time, don’t despair.  Follow me to Cassiopeia — we’ll have an easier time there!

All three of the stars we're going to look at in Cassiopeia can be seen on this chart --Alpha (α) and Eta (η) are at the top and near the center, and Iota (ι) is tucked in to the bottom near the right corner. (Stellarium screen image with labels added, click to enlarge)

Alpha (α) Cassiopeiae  (Schedir)
RA: 0h 40.5m   Dec: +56° 32′
Magnitudes:  2.4, 9.0
Separation:   71.2″
Position Angle: 281°   (WDS 2010)
Distance: 228.5 LY
Spectral Classification: K0
Rating: Easy to Moderate

Now the magnitudes of the primary and secondary of Alpha (α) Cass are almost identical to those of the Polaris pair.   But there’s one major difference — the two stars are four times as far apart.  That means it’s a whole lot easier to see the secondary.  And — even better (!) –  it will also give you a very good idea of what to look for when you go back to search out the Polaris secondary again — because visually, that secondary is a virtual twin of the Polaris secondary.

Easy to separate in a 60mm scope, easy to moderate in a 50mm scope, and a gold beauty in both scopes! (East & west reversed, click to see a close-up version)

I had no problem seeing the ninth magnitude companion with the 20mm Plössl (40x) parked in the 60mm scope.  It’s nowhere near as obvious as the 2.4 magnitude primary, of course, but it’s weak white point of light was beaming back at me very distinctly.  In the 50mm scope, though, you’ll find it’s noticeably more difficult.  I was able to pull it out of the primary’s glare with the 15mm Plössl (36x) with some persistent peering, but if you don’t see it at that magnification, try something in the neighborhood of the 7.5mm eyepiece (72x).

I rated this one moderate because of the disappearing act it might perform in a 50mm scope.  It’s easy in the 60mm refractor.

And don’t ignore the stunning color of the primary — it’s a gold beauty!

Eta (η) Cassiopeiae (Σ 60)
RA: 00h 49.1m   Dec: +57° 49′
Magnitudes:   3.5, 7.4
Separation:    13.1″
Position Angle:   319° (WDS 2010)
Distance: 19.4 Light Years
Spectral Classification: G0, K7 (Kaler) or MO (WDS)
Rating: Easy

Eta (η) is easy, easy, easy  ………..  and downright beautiful.  At the smaller apertures we’re using, the primary has a weak gold color, and the secondary displays a slightly darker and richer orange — both of which are welcome sights on any night at any aperture.

Easier than easy even -- and the colors can be hypnotizing on a quiet, dark night. (East & west reversed to match the refractor view, click for richer color)

As an appetizer, I recommend the 20mm TV Plössl in both scopes (40x in the 60mm, 27x in the 50mm).  That places the two stars very close together, yet still distinctly apart.  Then, for the main course, work your way through your range of eyepieces until you reach a focal length similar to the 7.5mm Celestron Plössl — a heavenly desert of a view if ever there was one.

The 7.5mm eyepiece gives me 107x in the 60mm scope and 72x in the 50mm — and there’s plenty of light coming from these two stars to provide a bright, clear view.  But be careful here!  As you watch the two stars get farther apart with the increase in magnification and see the diffraction rings expand into view, you’re exposing yourself to one of the most addictive activities known in this sector of the galaxy.

And there is no known cure.

Iota (ι)  Cassiopeiae (Σ 262)
RA: 02h 29.1m   Dec: +67° 24′
Magnitudes        AB: 4.6, 6.9    AC: 4.6, 9.0
Separation         AB: 2.8″           AC: 7.1″
Position Angle   AB: 231° (WDS 2010)   AC: 116° (WDS 2010)
Distance: 141.6 Light Years
Spectral Classification   A:  A5    B:  F5    C:  K1
Rating: Moderate to Difficult

Now I thought twice about even including this one — mainly for fear it might not offer an iota of a chance for someone new to this line of endeavor.  And here’s why.

About a year ago, when I was doing a side by side comparison test, I aimed two 60mm f/16.7 refractors at Iota (ι), using a pair of 17mm Celestron Plössls — one in each scope — that come from the same long line as the 7.5mm Plössl I’m using for this series.  Those two eyepieces gave me a 59x view, and that was more than enough to see both the 6.9 magnitude secondary and the 9.0 magnitude “C” star.

But when I turned the f/13.3 60/800 in use for this series on Iota (ι), I drew a blank.  Well, not a blank — the primary was obvious at least.

The culprit was poor seeing — about a notch below the I on this scale — in other words, really rotten.  Actually, the seeing may have been even worse than that.  Because for three consecutive nights, I could barely get the primary — or any other star, for that matter — to come into focus.  On the fourth night, using a 60mm f/15 refractor equipped with the 20mm TV Plössl (45x), the seeing was a rousing four — and all three stars threw up their stellar hands and appeared in plain sight without a fight.

A devil of an ordeal, but when you get it to cooperate, it's a stunning little sight in a small scope! (East & west reversed once more, click to get a closer look)

I was about to go grab the 50mm Zeiss to give it a chance, but as I was trying to pull myself away from the stunning view of those three ravishing, alluring, siren-like points of light, I realized they were beginning to fade  —-  out  —-  completely.

Clouds.

They did it to me again.  Covered the whole darned sky.

Heavens to Zubeneschamali!  Been had again!  Rats!

But I’ve decided to include it anyway, as an object lesson in what seeing can do to your observing session.  On an average night, and certainly on a good night, you should be able to coax both of those close companions into view in the 60mm scope.  I’ll exclude the 50mm for right now — when I get another good night, I’ll give it a try and see what happens.

But back to poor seeing for a moment.

One night you’ll swear there’s no way under the stellar vault that whatever star you’re searching for can be seen — and the next night, it’ll be right there waiting for you in plain sight, grinning from one photonic edge to the other.  I’ve been doing this a long time — and after several nights of poor seeing, I still find myself beginning to wonder if my eyes are failing me, or if the scope has suddenly become incapable, or if the eyepieces are defective.  Suffice it to say, it can  –  and it will  –  play terrific tricks with your mind.

Don’t worry, though, you’ll get used to it.

Because when the seeing suddenly improves, and the veil is pulled back once again to reveal that elusive star in all its sharp, crisp, clear clarity — the frustrations will disappear.  Why?  Because your memory banks will be erased, reformatted, and replaced.  All you’ll remember is those distinct, gleaming, sharp pinpoints of light blazing away from in front of their velvet black background.

And now, if I could only remember what it was I was about to say before my cranial circuits were re-set  …………………………..

Oh, yeah  ………………   Let us not dawdle any longer!

Tour number three lies immediately around the celestial corner, so to speak, and I promise an astronomical improvement in atmospheric conditions!  Let’s go see what’s next!

PLENTY!

Which is to say a whole heck of a lot more than you may have been led to believe by the nay-sayers and those addicted to aperture, the ones who will lead you down the road to financial purgatory faster than a speeding photon disappearing into a black hole.  Not that I’m not fond of a bit of aperture.  Many a night finds me parked behind the long white tube of a five inch or six inch refractor, or occasionally an eight inch SCT.

But  —-  the purpose of these tours is to demonstrate that the heavens hold an abundance of stellar wealth which is visible in small apertures.  Many are the lonely objects just waiting for a sixty millimeter lens to pay them a visit.   So think of this as your chance to provide some visual comfort to a distant collection of forlorn photons.

Greg is covering similar territory with his DSC-60 posts, which can be found by clicking on the green “DSC-60″ tab at the upper right of the home page, as well as by scrolling down to “DSC-60 Project” at the bottom of the “Select Category” window on the left side of the home page.  I’ll provide a link to those posts as we go if I’m covering the same territory.  The primary difference is these 50mm/60mm tours will focus on a small area of the sky — usually a single constellation — and provide four or five stars that you can observe easily over the span of thirty minutes to an hour.  I’ll go back over some stellar territory that either Greg or I have covered previously at larger apertures, and I have a few locations in mind already that have yet to be scrutinized by either of our pairs of probing eyes from the eyepiece side of a telescope objective.

So think of this as a spur to practice grab ‘n go astronomy with these small-apertured scopes, which are ideal for quick observing sessions.  Between the DSC-60 series and this series of tours, we hope to get one message across loud and clear — there are countless stunning sights to be seen in apertures of fifty and sixty millimeters!

The Equipment

I’ve been thinking about a series of this sort for some time, and finally was prompted to get going with it when a new double-sided mount arrived on my doorstep from the albion shores of distant England.  The mount is called the Sky-T, made by Synta, which currently is not available in the U.S.  So by the time it reached my Oregon address, it had a few miles on it, but was otherwise unscathed.  It took a few adjustments to get it working properly, but once I got that squared away, I found I had the ideal platform for mounting a 50mm scope and a 60mm scope side by side.

Up high on the left is the 60mm f/13.3 and clingingly tighty to its saddle on the right is the Zeiss 50mm f/10.8. In the supporting role is the Sky-T alt-az mount with very smooth slow motion controls. Click on the photo to get a closer look.

Which leads us to the scopes.

There doesn’t seem to be a lot available in the way of 50mm refractors, apart from finder scopes.  Swift made an excellent 50mm scope many years ago, which rarely comes up for sale on the used market, and I believe Tasco sold a 50mm at some time in the distant past, which is also seldom seen among the ads for used refractors.   And Stellarvue has offered their 50mm finder as a stand-alone refractor, dubbed the Lil Rascal.  It’s short focal length makes it better suited for use as a finder, as opposed to a double-star splitter, but since you can swap eyepieces in it at will, it merits consideration.   I was fortunate enough to come across a 50mm f/10.8 Zeiss on Amart, so I grabbed it quickly, and have been very pleased with it.  The views are crisp, bright, and mouth-wateringly sharp.

The 60mm scope we’ll use for these tours is one I put together from various parts.  The lens is an 800mm focal length Carton in a silver aluminum cell, which I mounted in a white aluminum tube.  That cool black lens hood is a yogurt container with the bottom cut out of it that fits around the aluminum cell like your frosty hand in a warm glove.  The final touches were a 1 1/4 inch Antares rack and pinion focuser and a 10×30 Celestron finder, which is the same one that comes with many of Celestron’s smaller scopes, including the six inch SCT.  I’ve found that particular version has a field of view which is bright enough that I can see the crosshairs outlined against a dark sky — a rather rare trait, but I’ve got several of them, and all of them have that uncanny talent — and you can frequently find them on the used market for about $25.00.  I believe the lens and cell cost another $25.00, the tube was somewhere around $10, and the focuser was about $45 — and the full container of yogurt was about three bucks.  That all comes to right at $108 — not bad for a great little 60mm scope.

And that brings us to eyepieces.

The Televue green and black actually make a colorful match with the Celestron orange and black!

We’re only going to use four for these tours: three Televue Plössls — 20mm, 15mm, and 11mm — and an old orange-lettered, magical 7.5mm Celestron Plössl.  We’re not attempting to ferret out faint photons and elusive secondaries trapped at 200x in the glare of shimmering diffraction rings — that’s done better with larger apertures.   The idea here is if whatever we’re chasing can’t be seen in the 7.5mm eyepiece, then it’s out of range for the purposes of this tour.  If you want to torture yourself with dim views at 200x, I’ll look the other way.  That’s not to say it can’t be done in a 50mm or 60mm scope — I’ve done it more times than I can count — but my eyes have always rebelled at the visual torment I was forcing on them.  You won’t be able to resist trying it, anyway, so there’s no need for any encouragement from me. 

But the intent here is to see what can be seen in scopes of small aperture at reasonable magnifications — and without investing a fortune in eyepieces.  I like the Televue Plössls, but GSO or Meade or Orion Plössls will do just as well, as will University Orthoscopics, or the older Celestron Orthos which can frequently be found on the used market — or just use whatever you have on hand.  You can even mix up the brands and types — nothing is carved in stone here.

This series is also written with the beginner in mind, or at least those without a lot of experience at the eyepiece.  So I’ll categorize each star we look at as easy, intermediate, or difficult.  Some will fall into two of those categories for various reasons, which will be explained as we go along.  And I’ll even include a few observing tips for a nominal fee — free!

In fact, I’ll throw in one tip right now.  Unless you’re one of those rare people — and there really are a few of them — who can observe from a standing position and remain absolutely motionless over the eyepiece, sit down and make yourself comfortable!  It is absolutely amazing how much more you can see when you’re comfortably seated at the eyepiece.  A chair with an adjustable level seat is the best investment you can make — it will literally have an astronomical effect on your observing enjoyment.  You’ll see things from a seated position that you’ll never catch the first glimpse of when standing up.  An excellent example of that is the Polaris secondary, which is discussed in the second tour in this series.

And if position angles and celestial directions make your head spin and cause chronic spatial dislocation, you might want to read Greg’s post on the subjects here.  Some time invested in reading it slowly and carefully, and going back over it a second and third time — or at least until you have a good grasp of its contents — will make your time under the stars many times more enjoyable and rewarding than it would be otherwise.  Without a basic acquaintance of celestial directions and motion, you’re likely to feel like you’ve been dropped into the middle of a large city at night with no map.

So enough of the introductory information.  Put on a coat, grab your scope, and let’s get going.

Oh — don’t forget your Star Splitter hat.

You’ll never get the hang of this without that hat. 

Tour number one starts  …………………  here!

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

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

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

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

Albireo (Beta Cygni)
RA: 19h 30.7m   Dec: +27° 58′
Magnitudes: 3.2, 4.7
Separation:  34.8″
Position Angle: 54°  (WDS 2010)
Distance: 380 Light Years
Stellar Classification: K3, B8
Rating: Easy

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

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

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

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

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

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

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

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

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

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

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

61 Cygni (Σ 2758)
RA: 21h 06.9m   Dec: +38° 45′
Magnitudes: 5.2, 6.1
Separation:  31.4″
Position Angle: 152°
Distance: 11.4 Light Years
Stellar Classification: K5, K7
Rating: Easy

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Omicron-2 (ο-2)  (S 743)
RA: 20h 15.3m   Dec: +47° 42.5′
Magnitudes: 4.2, 8.4
Separation: 208.4″   (WDS 2002)
Position Angle: 177°
Distance: 1109 Light Years
Spectral Classification: K3, B3
Rating: Easy

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

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

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

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

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

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

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

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

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

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

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

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

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

Now I know some folks prefer to have their eyeballs blasted with a sudden explosion of photons radiating from two luminescent dancing points of adjacent light.  I certainly include myself in that group — my knees knock and my focus fingers fidget when I see Porrima or Castor in the sky.  But it’s kind of like listening to the deafening roar of the ocean during a raging storm — it’s invigorating and awe inspiring; it makes the adrenalin rush and pulse through every square inch of you.  But but after an hour of that, you get tired of having your senses assaulted — you need a break.  So you walk away from it half a mile or so to a place where there’s total silence, and you find the sheer absence of sound is suddenly very soothing.

So what we’re going to do here is attempt to massage the soul with silence, while soaking up the subtle beauty of closely spaced pinpoints of silently pulsing starlight   ………….   which means we’re not in a hurry.  Get a hot cup of tea, put on a warm coat, pull up a chair, clear your head, and above all, make yourself comfortable.

Usually for a tour of this sort, it’s good to have an anchor point from which to start.  In this case, that would be Zeta (ζ) Cygni, an interesting star in its own right — and, as it turns out, also a binary.  But at a claustrophobically spaced four one hundredths  of an arcsecond from the primary — which translates into eight AU’s (an astronomical unit being the distance between the earth and the sun, about 93 million miles) — the components are about as close as they can get without being pulled into one another.  In fact, something similar to that actually took place many eons ago — you might want to take a look at Jim Kaler’s discussion of it.

Zeta (ζ) Cygni shines at a moderate magnitude of 3.2 in the Swan's eastern wing. We're going to wander through the area to the east and north of it, following in the footsteps of several observing greats: Sirs William Herschel and John Herschel, Sir James South, Admiral William Smyth, and another father-son duo, Friedrich Georg Wilhelm von Struve and Otto von Struve. (Stellarium screen image with lots of Greek letters added, click for a larger view).

But let’s get started quickly before I’m tempted down the winding path of digression once more. 

One quick aside, though — all of the stars in this tour are best seen in a five or six inch refractor, although a four will do almost as well — but anything less will lose the effects I’m going to describe here.  If you’re using a reflector, I suspect a six inch would be a good place to start, as would a six inch SCT.  A moonless night is a big help, but if you can’t avoid it, you’ll do better with one of the larger apertures — and if the seeing and transparency aren’t average — what we call a III here — wait for a better night.

Our first star, Σ 2762, is found one degree directly west of Zeta (ζ) Cygni. It forms a neat little triangle with 5.75 magnitude HIP 104185 to its north and 6.5 magnitude HIP 104653 to its east. (Stellarium screen image with labels added, click on the chart for a larger view).

Σ 2762 (H II 97) (S 775)
RA: 21h 08.6m   Dec: + 30° 12′
*****      Magnitudes       Separation       Position Angle        WDS Data
AB:           5.7,   8.1                  3.2″                      305°                      2010
AC:           5.7, 10.2               59.3″                      229°                      2007
AD:           5.7, 10.1               72.7″                        66°                      1999
Distance:  444 Light Years
Spectral Classifications:  B9 for all
Status:  AB gravitationally linked (Haas), “C” optical (Burnham), “D” undetermined

The first time I got a good look at Σ 2762 — it took about 30 seconds to register –  a loud thud echoed across my observing deck as I dropped like a rock into the seat of my observing chair.   I was captivated  –  completely.  And it has several subtle attractions which emerge slowly the longer you look at it.

First, you’ll find you need a bit of magnification to pull the 8.1 magnitude secondary away from the primary.  It’s a bit tight at 3.2″ — and don’t under-estimate the 2.4 magnitudes of difference — but it’s certainly not difficult to separate.  An 18mm Radian (118x) in my five inch Meade refractor separated the two very comfortably.  Once you pry the secondary free from the primary, you’ll notice the two stars flanking the AB pairing ninety degrees to either side, which are 10.2 magnitude “C” and 10.1 magnitude “D”.  And after you’ve picked those out, your eyes will be drawn to a neat little grouping of four stars just northeast of “D” — not part of this system, but just an added touch which improves the view.

"I was captivated -- completely." (East & west reversed to match the refractor view, click for a version without this caption).

So after you’ve had time to absorb the entire view, you find yourself staring at a rather attractive and eye-catching group of eight stars perched in the center of your eyepiece, with no competing starlight elsewhere in the field of view.  I’ve sat back and let this view calm my star-cluttered thoughts several times in the last month or so.

In the years since its photons first found their way into William Herschel’s twenty foot reflector on September 15th, 1783,  Σ 2762 has had a lot of attention.  After assigning it a catalog number of H II 97, Sir William described it as a “Treble. About 1 degree preceding Zeta, towards the 41st Cygni; a large star.  The two nearest extremely unequal.”

Sir James South added his observation of it (S 775) forty-one years later, on September 24th, 1824  –  “Double, 6th and 10th magnitudes; small, blue.”  –  on a night that apparently was a bit frustrating: “The dew is so intolerably troublesome, that I am obliged to discontinue the observations; and I do it with the greatest reluctance, for the night is unusually fine.”

F. G. W. von Struve, whose name is attached to this star, observed it in 1829 and described the colors as “greenish white and blue” — and also noted a third star at 225 degrees and a separation of 57.8″, which is a close match for where “C” is now.

And four years later, Admiral William Smyth added this: “A very neat double star, towards the tip of the Swan’s right wing [east], directly preceding Zeta (ζ) Cygni by about 1° ½ due west.  “A” 6 ½, dull white; “B” 9, pale lilac; and there is a third star in the sp  [south preceding] quadrant.”  (p. 497 of the The Bedford Catalog)

And then I happened to wander onto the scene a mere 178 years after the Admiral’s observation, on a night when the moon was about fifty percent full and hovering forty degrees to the east.  That moonlight had the effect of muting the colors quite a bit, and as a result the primary matched Smyth’s description of “dull white.”  On a darker night it picked up a weak tinge of yellow, and I detected just the slightest hint of blue in the secondary.  “C” was a bit difficult on that first night because of the moon’s reflected light, but under darker skies it recovered and reclaimed its position very distinctly.

That grouping of four stars to the north of the primary was also more obvious on a moonless night, and in fact was so enticing I just couldn’t resist putting them and the four Σ 2762 stars under my magical 7.5mm Celestron Plössl (157x).  All eight of those stars, shimmering at that magnification against a backdrop of black velvet sky, etched their way deeply into some secret corner of my memory.  As I look at the sketch, and that memory comes into sharp focus now, the peaceful silence of that night is just as real as if I was still sitting at the eyepiece.  You could have heard a pin drop a mile away.

But let’s ease out of this calm moment now and hop northeast about three degrees to one of Otto von Struve’s discoveries,  OΣ 437.  If you look at the second chart above, you’ll see that Σ 2762, 6.5 magnitude HIP 104653, and 7.3 magnitude HIP 104733 form a line that points almost directly at OΣ 437.  You’ll find it wedged between 7.1 magnitude HIP 105234 and 6.0 magnitude HIP 105432.

OΣ 437
RA:  21h 20.8m   Dec: +32° 27′
*****                      Magnitudes       Separation        Position Angle       WDS Data
AB:                             7.2,  7.4                  2.4″                       20°                      2010
AC:                            7.2, 11.2               79.9″                     142°                      1998
CD (POP 1232)    11.2, 11.2               15.0″                       21°                      1990
Distance:  239 Light Years
Spectral Classification: G4 for all except “D”
Status:  AB gravitationally linked (WDS), others undetermined

Now the AB pair of this triple star is noticeably tighter than the AB pairing of Σ 2762, but it’s more evenly matched in magnitude, making it just slightly easier to pry apart.  Still, it took some judicious application of magnification to get those two to relax their grip on one another.  But when you get it just right, you find yourself staring at two very small pinpoints of tangerine tinted light, right in the center of a dim field of view, notable for not having anything else available to lure your eyes away from the display at the center.

Stare deeply into those tangerine-tinted photons ............. (east & west reversed, click for the caption-less version).

My Meade AR-5 called back the 7.5mm Celestron Plössl (157x) for another round, which turned out be the perfect choice.  I could see the two stars trying to leap apart in a 10mm Radian (118x), but the additional magnification of the 7.5mm did the trick, settling down to just a bit more than a hair’s width apart.  A week later, on a night when the seeing was barely a I,  I managed to split them in my six inch Celestron f/8 refractor using a 5mm Radian (240x) — and discovered what two oscillating and vibrating tangerines surrounded by diffraction rings can do to your emotions.  All I can add is amazing, amazing, amazing  …………….   just totally incredible.

“C” was no contest in the AR-5 at 157x, but not particularly notable — except, that I could see a hint of duplicity in it.  At a distance of fifteen arcseconds apart, their twin 11.2 magnitudes of faint light should easily separate in a six inch refractor, based on my experience with similar dim pairs recently.  So I gave it a try the night I had the six inch Celestron under the skies, but both of them eluded my thirsty eyes.  They were just too faint for the poor seeing conditions that night — on a night with average seeing, though, they should be no contest in a six inch refractor, so I shall return.

The OΣ in this star’s designation refers to Friedrich Georg Wilhelm von Struve’s son, Otto Wilhelm von Struve, who recorded his first observation of the AB pair in 1845.  He measured the separation at 1.31″ and the position angle at 61.8 degrees.  Since that time, the two stars have slowly widened — an 1898 observation by Hussey (see the note on sources at the end of part two) put them at 1.64″ and 43.9 degrees.

I found two other recorded observations of OΣ 437, both of them in Haas’s book: “Hartung: ’75mm easily resolves this close orange-yellow pair.’  Heckman, 250mm, 185x: ‘Superb yellowish pair of equal magnitude.’ “  That first observation in a 75mm scope surprises me — I’m going to have to try that with my 76mm Tasco.

My impression of the color in the AB pair was more tangerine than yellow, with a slight bit of white present — just enough to make those two stars seem a bit brighter than their 7.2 and 7.4 magnitudes.  I’ve noticed when there’s enough white in an otherwise colorful star, the overall color has what I can best describe as a metallic quality.  It seems to be impossible to reproduce that effect in a sketch or a photograph — the only way to experience it is visually.

But to get back to my comment in the first paragraph on this star, once you’ve succeeded in splitting this pair, in order to get it really right, give this view some time to work its magic — don’t give it a quick glance and then rush off to some other object.  You need to look at this pair for ten or fifteen minutes — and you most definitely need to do this on a dark, moonless night.

Get yourself situated comfortably, relax, look into the eyepiece, and let those orange-tinted photons massage your vision.  After several minutes, the mental chatter in your head will begin to calm down of its own accord, and you’ll soon find there’s something very appealing about the appearance of these two points of orangish-white light glowing all alone in the deep black void of interstellar space.  It was the view of these twin points of light that prompted the phrase “delicate aesthetics” to slip into my thoughts from the fathomless depths above.

And after that view is fixed firmly in your memory  ……………..   take a deep breath   ………………   and then we’ll wander up to Upsilon (υ).

We need to make a turn to the north here, and although there aren’t any guide stars along the way on our chart, you should have no problem seeing Upsilon (υ) lying two degrees north of OΣ 437.  It shines at a combined magnitude of 4.4, making it stand out from the much fainter background stars.

Upsilon (υ) Cygni (OΣ 433) (66 Cygni) (h 932)
RA: 21h 17.9m   Dec: +34°  54′
*****                  Magnitudes        Separation         Position Angle       WDS Data
AB:                       4.4, 10.0                 14.2″                       220°                    2008
AC:                       4.4, 10.0                 21.2″                       181°                    2008
AD:                       4.4, 12.0                 57.1″                       308°                    1998
AE (BU 9011)     4.4, 10.0                34.9″                          67°                    2000
Distance:  901 Light Years
Spectral Classification:  All B2 except for “E”
Status: AB optical (Burnham), others undetermined

Now you’ve got to do some digging here — the magic in this view requires concerted effort, and probably at least five inches of aperture to see all of it on a dark night, meaning the disappearing “D” and the very elusive “E.”

I was wielding my Meade AR-5 the first time I wandered north to Upsilon (υ), but it was on the same night as the fifty percent full moon described in my description above of Σ 2762.  In this case, because all of the companions were closer to the primary than those of Σ 2762, my attempt to see anything than other than the primary was pretty much hopeless.  I had just the faintest glimpses of “B” and “C” attempting to emerge into the moonlight from that primarial glare, but I finally gave up any attempt to sketch this one and just wrote “hopeless — need a darker night.”

But I could see that wasn’t going to happen for a while, so even though the moon was well on its way to full, I returned to the search again with an extra inch of aperture — and eventually a whole lot more magnification.  A 14mm Radian (109x) in my six inch f/10 refractor produced a primary with an intense yellow-white glow (metallic again), and the extra inch of aperture allowed “B” and “C” to come out of their dark hiding spots.  “E,” which is the same magnitude as those two, remained out of sight.  That was a result of a diffuse halo of light surrounding the primary, which was a bit stronger where “E” was supposed to be — and 12th magnitude “D” was nowhere to be seen.

Subtle starlight yielding to muscular magnification ............. (east & west reversed again, click to lose this caption).

So I decided to start increasing the magnification until I reached the point where the eyepiece began magnifying more glare than starlight.  Usually the glare wins that race, but I got lucky in this particular case — before I knew it I was peering into the pinhole-sized lens of a 4mm Astro-Tech Plössl (380x !!!) and found myself looking directly at the disappearing “D.”  I had already pried the elusive “E” out of the glare with the four millimeter’s slightly less powerful relative, a 6mm AT Plössl (253x), which had also given me an averted vision first glimpse of “D.”

Now your first impression might be that this was less a case of subtle starlight and more one of muscular magnification.   But  ……..   let us not be so hasty here.  There is something very haunting about the view of eight dancing points of starlight magnified three hundred and eighty times in the center of a pin-holed lensed Plössl.  Really.

At that magnification, there’s certainly a lack of sharpness, but its absence is more than made up for by the shimmering, almost ghost-like dance of those shapeless concentrations of light.  There’s a word for it in German — unheimlich — meaning uncanny, intangible, mysterious, elusive — in other words, a word for a quality that defies description.  If you can picture that, you know exactly what I mean.  If you can’t, you’ve got no choice but to go outside and try it.

I probably should come back here on a dark night with the AR-5 and see if I can do as well, and possibly recover some of the aesthetic appeal that I’m sure I didn’t see.  I suspect what I’ll find is that 250x on a dark night in a five inch refractor will match the 380x in the six inch under all that moonlight.  On the other hand, I don’t want to do anything to disturb that shimmering memory of dancing light right now.  I think I’ll just leave it this way.

John Herschel discovered this star in 1827, describing it as “Triple. L. white. Both the small ones red.” His measurements of distance seem to be well off the mark for AB and AC, but in looking at the data in the Lick publication mentioned in the source notes at the end of part two of this post, “B” and “C” have shown virtually no motion since the 1890′s.  I’m not sure how that red arrived in his eyepiece since all three stars are the same spectral class, B2 — but maybe a dark night will provide a hint.

And now we move on to part two, and a neat little triple star discovered by Sir John’s sometime observing partner, James South.