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Rho-ing West in Orion: Rho (ρ), Eta (η), and Wnc 2

January 10th, 2011, 9 PM
OK – I’ve been clouded out for the past seven days, and according to the weather forecast, tonight’s clear skies are IT for at least the next week, so what to do to make the night interesting?  Well, heck, I’ll do what I always do in that situation — look at a few old favorites first!

Db Ds (Click on image for a larger view)

Tonight my 105mm f/14.3 refractor leads the way, and riding side-kick on top of it is a 60mm f/16.7 home built scope with a Carton lens.  I call this my Double Barrel Double Splitter combination – or Db Ds for short.  So after pointing the two scopes at Polaris and making sure the finder and the 60mm scope are aligned to the 105mm, I turn it back around to take a look at M42 and the Trapezium

Orion in all its beauty! Click on this and the other images for a larger view. (Stellarium screen shot with labels added)

Hmm …. bad vibrations.  As in bad seeing.  As in stellar jumping jacks in the eyepiece.  Not good, but pretty normal lately, so I just decide to back off of the magnification and live with it.  No sighting of “E” or “F” in the Trap, so up to Alnitak — the Flame Nebula is barely visible — and down to Sigma (σ) Orionis for a look at that quadruple system.  I’m able to pick out the faintest of that bunch of stars, the 8.8 magnitude “C” component, so now it’s back up north a bit to Meissa to see what’s going on there.  Not much, really — although Meissa and her three companions are stunning as always — but I can see the seeing is a bit better up here.   Still,  I have no luck with OΣ 111 to the north of it — I’ll split that thing one of these days!

By now I’ve been outside for about an hour and it’s time to take a short break from the 35 degree air and its 25 mph gusts of wind, so inside I go to get a cup of tea, warm up, and peruse my charts.  Since I’ve been poking around in Orion anyway, I look to see what’s “available” on the west side of it.  My eyes are drawn to Eta (η), which has a reputation for being difficult to split, and also to a star I looked at a couple of years ago with a very unusual name, Wnc 2, which I remember as dim and closely spaced.  Thinking about the poor seeing, I look over the area for something a bit easier.   Somehow I end up at Rho (ρ) Orionis — magnitudes of 4.6 and 8.5 with a separation of 7.1 arcseconds.   Hmmmmm ….. quite a difference in magnitudes for that separation.  But what the heck.  If you don’t try, you won’t fail.

So I put my coats(!) back on, pull my hat over my ears, pick up my cup of tea, and return to the cold land of the  whistling wind.

Rho (ρ) Orionis  (Σ 654)  (H N 21)         HIP: 24331    SAO: 112528
RA: 5h 13.3m   Dec: +02° 52′
Magnitudes: 4.6, 8.5
Separation:  6.9″
Position Angle: 63°   (WDS 2007)
Distance: 344 Light Years
Spectral Classification: K2

Enlarged view or our viewing area. Rho (ρ) is at the upper right, Wnc 2 towards the center and next to 27 Orionis, and Eta (η) is below it. (Stellarium screen image with labels added)

My charts tell me that if I start at Mintaka, the westernmost of the three belt stars of Orion, and follow the line formed by those three stars for a distance of 1.5 times its length, I’ll come out just barely north of Rho (ρ) —  and it works like a charm.  So I sight down the length of the 105mm tube, look in the finder, center it, and then — not expecting a lot of luck — peek into the 83x of an 18mm Radian.

And there they are!  Both stars!  Just like that!  No searching, no squinting!  No failure here!  The 8.5 magnitude secondary is a very fine point of light next to an orange primary, and both are just as obvious to my eyes as the sinking crescent moon in the west.  And to top it off, I can see that little pinpoint of fine light in the 20mm eyepiece (50x) of the 60mm scope.  Now that I find hard to believe!

I swap a 15mm Plössl (67x) into the focuser just to confirm it isn’t my imagination.  It isn’t.  I try an 11mm Plössl (91x) next, but it’s actually a bit too much because it’s magnifying the glare from the orange primary.    Now I move the 11mm Plössl to the 105mm scope, which gives me 136x and very little interference from the glare.  But the best view is really at 100x with the 15mm Plössl.  And faint as that secondary is, I can definitely see a blue tint to it!

Not bad for the first part of an unplanned observing plan!

Eta (η) Orionis  (Saiph al Jabbar)  (Dawes 5 — DA 5 in the WDS)  (H VI 67 — AC only)
HIP: 25281    SAO: 132071
RA: 5h 24.5m   Dec: -02° 24′
Magnitudes  AB: 3.6, 4.8       AC: 3.6, 9.4
Separation   AB: 1.8″             AC: 115.1″
Position Angle  AB: 77°  ( WDS 2011)        AC: 51°  (WDS 1998)
Distance: 901 Light Years
Spectral Classification: B1,B2

Well ……. since I’m off to a good start, why stop?  On to part two of this stellar version of Mission Impossible.

Eta (η) is easy to find — just draw a line from Mintaka to Rigel, and you’ll see it about a quarter of the way from Mintaka, a bluish white star like most of the bright stars in this area.  It occurs to me that from the perspective of prudence, it would be smart to stay with the 105mm scope on this one — 1.8 arcseconds in this kind of seeing is going to be a stretch.

I start with a 14mm Radian (107x) and can see the image is elongated just a bit horizontally.  So I move up a short step with a 12mm Radian (125x) and that elongated form is desperately trying to pull itself apart.  A 10mm Plössl (150x) really isn’t much better, but the way the image is weaving and wobbling, I’m wondering if there’s any point in going further with this.

But what the heck — someone, I believe it was me — said, “If you don’t try, you won’t fail!”  So, here goes.

I walk into the house to find some warm air and my next two tools of the trade — a 9mm UO Ortho (167x) and a magical 7.5mm Celestron Plössl (200x).  If Mission Impossible it is, then we’ll dig deep before pushing the self-destruct button.

Back out in the cold, I remove the 10mm Plössl and carefully place the 9mm Ortho in the diagonal.  I bend slowly down to the eyepiece with both eyes closed, carefully open my right eye — and —- and —– and ——  BINGO!   Two touching globes of light!  At least for brief moments when the seeing settles down.

So this calls for the mysterious magical powers of that very unique 7.5mm Celestron Plössl that I found in a box of parts given to me by a neighbor a couple of years ago.  With a sense of regret and hating to break the bond that has just formed between me and the 9mm Ortho, I reverently remove it and gingerly replace it with the 7.5mm.

Magical, mysterious, maybe even miraculous!

Can you stand this suspense?  NO?  Well hang on, anyway, because here we go  —— with a feeling of stirring anticipation and a sense of impending I awe, I place that little 7.5mm eyepiece in the diagonal —– and  —–   GOT ‘EM!   The magic eyepiece has done it once more!

What I see are two very distinct, very separate globes of light, which surprisingly, have a slight yellow tint to them.  And Haas noticed that also: “straw yellow and silvery yellow” is her description.  What these two stars really remind me of is Porrima.  When I split it last summer, it was near the meridian, so the two components were stacked one above the other in my eyepiece.  Eta (η) is also near the meridian tonight, and it’s pair of stars is lined up horizontally in the eyepiece — but other than that, they look remarkably similar.

Well, it just does not get any better than this. 🙂

Wnc 2        HIP: 25240    SAO: 132060
RA: 5h 23.9m   Dec: -00° 52′
Magnitudes: 6.9, 7.0
Separation:  3.1″
Position Angle: 159°  (WDS 2011)
Distance: 189 Light Years
Spectral Classification: F6

Alright, back down to earth now for a few moments to plan a strategy for locating our last pair.

Looking at the chart above, you can see that Wnc 2 forms a triangle with Mintaka and 31 Orionis, as well as with Eta (η) and 31 Orionis.  But I’m standing outside at the scope in a cold wind using the Sky and Telescope Pocket Atlas to star hop, not inside looking at a computer screen.  I’m holding the atlas in my left hand, with a small red flashlight clamped between it and my left thumb, guiding the 105mm refractor with my right hand, while looking into the eyepiece of a correct image 8×50 finder.  And I’m having no luck at all.

And the reason is that the image in the atlas — which also is the case in the Cambridge Double Star Atlas — shows a larger and brighter star at the location of Wnc 2 than what is actually there.  In other words, the image in the finder is not matching the atlas well at all.  After a couple of futile attempts, the lights come on in my chilled brain and I decide the smart thing to do would be to center 27 Orionis — which I can clearly see — in the finder, and then look in the eyepiece of the telescope.  So I do — and darned if I don’t see the little devil off towards the west edge of the eyepiece.

Geeez — I oughta do this for a living.

West is to the upper left in this refractor (mirror image) view.

Now this one is not really all that stunning, but the satisfaction of finding it more than makes up for that.  In the 105mm refractor, using a 14mm Radian (107x), this is a close pair, as well as relatively dim, which the sketch here shows pretty well. With a 15mm Plössl (67x) in the 60mm refractor, though, the stars are just barely separated.  Haas apparently didn’t look at them, but quotes an observation by Castle which describes the stars as ” ‘warmish’ without an obvious color.”  Yep, too dim for color, but by this time I would have welcomed a “warm” tone if I had seen it.

Now what in the name of the Orion Nebula does Wnc 2 stand for?  A quick look in the Cambridge Double Star Atlas reveals at least a name — F. A. Winnecke.  The full name is Friedrich August Theodor Winnecke.   Herr Winnecke was a German astronomer who published a list of seven double star “discoveries” on February 8th, 1869, some of which it turned out were already known.  More info on him can be found here,  and his list of seven stars is here.   If you look at that list, you’ll see that the double listed as Wnc 2 is in Eridanus, while the info for Wnc 3 matches the Orion coordinates.  Both the Haas book and The Night Sky Observer’s Guide, as well as the Washington Double Star Catalog, list the one we’re looking at as Wnc 2, however, so it appears that the list on the link has reversed the two.

And ….. that’s it for tonight.  Sorry, but it’s cold out here, the clouds are coming in, and I hear another cup of hot tea calling to me.

And since the weather forecast is calling for another week of rain starting in the next few hours, I need to go back to building my ark and practicing my Rho-ing technique.

Clear Skies!

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One Response

  1. John

    You’ve set a very high standard for star reporting. It is wonderful to be taken on a tour of the northern sky. Don’t know if we can ever match it from down under.

    When our skies clear we’ll give it a shot.
    At the moment while you are splitting stars, we can’t even split the clouds!

    Our temperatures are nearly similar to yours – except on the Celsius scale! Much more favourable for comfortable viewing – so it is teeshirt and shorts for us and long drinks of cool water.

    We’ll try to see the jewels in Orionn that you point out in such detail.

    From under the Southern Cross
    Daphne and Dom

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