DSC-60 – Visiting Mintaka, an old and comfortable friend

This is a DSC-60 Project observation –  for project details go here.

Splitting Tools for Mintaka: Yields easily to 50mm scope at low power.

Data from Double Star Club list

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20

Delta Orionis

05h 32m.0

-00° 18′

2.2, 6.3

52.6″

359

Mintaka (Delta (δ) Orionis)
RA: 5h 32m  Dec: -00° 18′
Magnitudes –   2.2,  6.8
Separation –   52.8″
Postion Angle –   0°
Distance:  915 LY
Spectral Classification –  B4

A couple bonus points to note about those stats – first, the declination – this star is just 18 minute south of the celestial equator. In fact, it’s the brightest star that close to the celestial equator.  Combine that with the PA of 0° – due north – and it’s a good way to help get yourself oriented. Oh – and that separation – 52.8 seconds – that’s just a tad more than the width of Jupiter as it appears in our sky when we’re closest to it, as is the case as I write this. So Jupiter could just fit between the two stars!

Click image for larger version. (Prepared from Starry Nights Pro screenshot.)

OK, I really should admit it – I don’t get out to Mintaka – Delta (δ) – often enough.  It’s one of those easy doubles I’ve known forever, but it’s in one of the best parts of the best neighborhood in the best universe – well, the only universe I know, although this multiverse idea is beginning to make some sense to me 😉

So this morning I found myself heading west on Orion’s belt, certainly one of the best known asterisms in the sky. Who can miss three perfectly spaced stars of almost even brightness (1.71, 1.68, and 2.2)  and straddling the celestial equator where they can be seen from almost any location in the world?  And Mintaka, a charming double, is one of those three – the western most. But it’s easy to ignore because the belt itself is embedded in a huge open cluster. what’s more, when you look at the other end of the belt  you get  the famous, but nearly invisible, Horsehead Nebula, not to mention the Flame Nebula and the delectable quadrupal star, Sigma Orionis.

But Mintaka is #20 on the Double Star Club list and I just had to see how it looked in a 60mm scope – well, at least my  8-inch SCT masked to 60mm. And it didn’t disappoint. This is not even close to being a challenge, even with a 60mm, but it has it’s own charm. While there’s quite a gap in magnitude between the two, the large angular separation makes this a good object to try to capture with binoculars. In physical terms given the angular separation and distance from us the faint companion orbits the primary at about a quarter of a light year.

What the 8-inch shows is a silver star with a smaller blue star tagging long. Stopped down to 60mm with the off-axis mask, the blue star turns to a steely grey, while the primary remains silvery.  Haas  saw the secondary as “very bluish white” and the primary  as “yellow white” and quotes Smyth and Webb as seeing the companion as “violet.”

Whatever color you see, there’s a lot more to this star that you don’t see.  Jim Kaler writes on his web site that the primary is “ALSO double, and consists of a hot (30,000 Kelvin) class B, slightly evolved, giant star and a somewhat hotter class O star, each radiating near 90,000 times the solar luminosity (after correction for a bit of interstellar dust absorption), each having masses somewhat over 20 times the solar mass. This pair is too close to be separated directly.” In addition, he notes the two stars orbit each other about every six days causing a slight dip of about .2 magnitudes.

Mintaka is another example of how Bayer made things up as he went when it comes to Greek letter designations. Usually the stars in a constellation follow the Greek alphabet starting wiht “alpha” being the brightest. But Mintake is Delta Orionis, yet Mintaka is the seventh brightest stars in Orion. Again, Kaler comes to the rescue here, saying Mintaka “received the Delta designation from Bayer, who lettered the belt stars in order from west to east before dropping down to Orion’s lower half to continue the process.”

Oh – and those two closely matched super stars we know as Mintaka. They’re heading for a short life and fiery doom.  Kaler notes that given their size “their only fate is to explode violently as supernovae.”  Hmmm… and a twin supernovae at that – wouldn’t that be something? What does happen when one star goes supernovae right next to another?

DSC-60: Tackling Meissa with a 60mm SCT!

This is a DSC-60 Project observation –  for project details go here.

from Double Star Club list

[  ]

22

Lamda Orionis

05h 35m.1

+09° 56′

3.6, 5.5

4.4″

43°

from John’s post:

Meissa (Lambda [λ] Orionis)
RA: 5h 35.1m  Dec: +09° 56′
Magnitudes –  A: 3.5     B: 5.5     C: 10.7     D: 9.6
Separation –   AB: 4.9″      AC: 28.7″      AD: 78.0″
Postion Angle –   AB: 50°      AC: 185°       AD: 272°
Distance:  1056 LY
Spectral Classification –  A: O8  B: BO.5

So you didn’t know they made a 60mm Schmidt Cassegrain? Niether did I.  But if you have one of the ubiquitous 8-inch SCTs – hmmm, come to think of it, I have three –  you can make an off-axis mask for it and turn it instantly into a color-perfect, 60mm scope. The cost can be close to nothing, the time about half an hour, and, of course, you do no permanent injury to the scope – the mask is something you put on and take off like a lens cap. It just cuts the scope down to 60mm.  I’ll do a separate post on why and how, but the object here is to see how this performs on Meissa a really wonderful star in Orion’s head.

I just got out at 5 am this morning as astronomical twilight began and quickly swung my “parked” SCT  (it stays set-up in a little observatory) to Meissa. What a sight this is. I didn’t even try to split it at first. I just enjoyed the wide field view. And I did this without the mask on the SCT so I was picking up most of that wonderful pattern of stars that make’s up Orion’s head and is part of an obscure open cluster. (See John’s post for details and charts. )

I was using a 24mm Panoptic which yields 83X and roughly a  49-minute field of view.  I wanted more, but serious twilight was closing in and a wider field eyepiece was 100 feet away in the house, so I stuck with the 24mm Pan, absorbed the beauty of the scene, then popped in a 16mm Nagler. Yep. I could see some signs of a split, but the stars were pretty fiery. So I quickly put on the off-axis aperture mask. (The off-axis part is to avoid the central obstruction.)

Voila! I now had 60mm of clear, unobstructed, color-free aperture. And what a difference. Meissa and her brightest companion  – yes, we’re only going after the brightest companion because that’s what the DSC list calls for – and that’s what is easily in reach of 60mm of aperture.  (I stress “easily” because John is always pulling rabbits out of the hat with his 60mm scopes – secondary,  tertiary and whatever you call the fourth star in a multiple just tumble out of his scopes like clowns out of a tiny car in the circus.  Not me. I stick with the easy stuff, by and large. I don’t have John’s eyes,really dark skies, endless patience and observing skills.)

Anyway – these are the sights I love. I just wanted to sit there an absorb it.  A large, white dot tinged with blue, and next to it a fainter, smaller, violet dot. Simply lovely. I mean these were the kind of perfect, round, well-behaved 60mm stars that we thrive on. Such order has a special ascethic of its own. Wonder if I can split it witht he 24mm? Out came the 16mm (125X) and back in went the 24 Pan – and yes, sure enough,there they were. Absolutely exquisite in their delicacy.

And at higher power? Well with an 11mm Nagler (182X) we had a big old honking split.  Yes, skies were steady! And yes, this is too darned much power for a 60mm if you follow the rules, as I generally do, and limit yourself to 60X per inch (2.5X per millimeter)  then 144X should be tops. But the heck with the rules, what about the 9mm Nagler – 222X?  Yes! We certainly have lost light – and eye position becomes absolutely critical, but we still have a perfect pair of stars.

That eye position business is interesting. John and I both became acutely aware of it when we first experimented with masking. The reason for it is simple. The higher the power, the smaller the exit pupil – the cone of light exiting the scope – and so of your eye isn’t in perfect position you don’t see anything.  There’s a wonderful eyepiece calcualtor on the Televue web site which I use when I want data like this and going there I learned that the 16mm Nagler gave me an exit pupil of about half a millimeter with the scope masked  which is right at the limit of what any sensible person recommends. (Hey, that’s 125X and pushing real near to the 60X per inch limit. ) Televue recommends no more than 2.5X per mm which would put the top at 150X and the 13mm Nagler – next in my case – delivers 154X and that, for Televue, is too much. And keep in mind, these folks are in the business of selling us eyepieces – so i put a lot of stock in their recommendations wwhen they start telling me NOT to use certain eyepieces they make.

But . .. who can resist trying? So the 11mm delivered an exit pupil of .33mm and the 9mm of .27mm – ridiculously small cone’s of light. No wonder eye position was absolutely critical.  But this is of more than academic interest. I learned something from it this morning. Eye position is pretty darned critical when you are using full aperture, too!

Now it’s interesting, because you don’t hit the wall – half a millimeter exit pupil – until you put in a 5mm eyepiece into your  8-inch scope – I’m talking unmasked now. WIth 200mm of aperture the numbers change. Using the 2.5X per mm rule that Televue applies you should be able to use 500X. But Televue has another rule that cuts in before then – they recommend 350X as the maximum “regardless of aperture.”  Of course they’ll sell you eyepieces that will take you higher – at least on the typical 8-inch SCT –  but they won’t recommend you use them to deliver such power.

But here’s what I found as I went back to viewing Meissa unmasked: I could see perfect stars  in the 8-inch SCT this morning – conditions were very good – but only if I was very careful to get my eye centered perfectly over the eyepiece. I’m sure someone will tell me that’s because I need to be on the axis of the light cone, or something like that – and this is hardly an entirely new revelation. But quite honestly, before fooling around with masking I was more likely to assume that  when stars  misbehaved it was because:

a – I didn’t have the focus correct

b – seeing was too poor to deliver a sharp image

To these two obvious thing I now have to add eye position, which with my Naglers, at least , is critical. I could really get quite an attarctive  split this morning with quiet , well-behaved stars, at several different powers and full aperture IF I was very careful about eye position.  Not all that easy to do.  I always observe sitting down, of course, but to position your eye correctly you need to really be just at the right height above the eyepiece and  in this case I used a hand to form a brige between the eyepiece  and my face to help steady it. (OK – I’m 70 -maybe younger folks would find this easier.)

If I don’t do this, the view unmasked is pretty if you like dancing, flaming stars.  In between the flaring you do see the split – and the additional aperture does show you the fainter companions John describes – and with the wide field provided by the 24 Pan and bright stars provided by eight inches of light grasp, Meissa really is beautiful. But I am also sure that if I didn’t have such great seeing conditions I would not have seen it that way – the 60mm would have provided an improvement for seeing Meissa A and B as clean, steady, dots. (One  other possibility – the scope I was using is a Meade LT-8 ACF – the Advanced Coma Free variety.  Perhaps that contributed to the view – I just don’t know. It would have been fun to have it go head to head against one of my older SCTs without the advanced design.)

DSC-60: Delta Herculis – will-o’-the-wisp

This is a DSC-60 Project observation –  for project details go here.

Stats from the Double Star Club List:

Delta Herculis

17h 15m.0

+24° 50′

3.1, 8.2

8.9″

236°

For a finder charts and a look at how Delta Hercules fares with other scopes read John’s post on it here, as well as the comments on that post.

The Double Star Club listing  treats this as a double only and the listing appears out of date. Again, John’s post deal with all four stars and gives more recent stats for the B component which show a separation of 12.4 seconds and a PA of 286°.  Given those numbers – in fact, given the earlier numbers even, you might expect this to be easy. It isn’t.  The C and D components are easy, even though they’re a couple magnitudes fainter, because they are each roughly three minutes from the primary.

Locating that B component – the object you need for the Double Star Club, is much more difficult.  With the 60mm and my  5.5 skies it was a will-o’-the-wisp. I saw it – but I suspect I saw it only because I had seen it a few nights before  using an 85mm and 102mm, so  I knew exactly where to find it. And with the little TV60 it definitely required averted vision and good dark adaption. I used a 4-2mm zoom and I could see it at the 4mm setting (90X), but only with averted vision. It pops in and out – more often out of view than in view.

So I would count this one as seen – barely – and also as a lesson in how difficult it is to see even a magnitude 8 star when it has a companion just 12 seconds away that is five magnitudes brighter. Much the same challenge you have with Polaris where the difference is greater, but so is the separation.

DSC-60: Iota Cancri – in search of the real Winter Albireo!

This is a DSC-60 Project observation – for project details go here.

]

Iota Cancri

08h 46m.7

+28° 46′

4.2, 6.6

30″

307°

I was looking for what I thought was the “Winter Albireo” – Iota Cancri, which is in my eyes a good imposter  of Albireo. I enjoyed it immensely – beautiful double, but the real fun started when I got back in the house, sat down with my notes and discovered I had not been looking at what others call the “Winter Albireo” at all. What’s more, I think I can make a case for my candidate – Iota Cancri, over the more popular one, h3945. But first, the background.

Iota is fascinating in its own right and quite easy to find on a spring evening since its one of the brighter stars in the dim region between Leo and Gemlni  that we know as Cancer the Crab.  If you can find the Beehive (M44) , a large and beautiful open star cluster, then Iota is the 4th magnitude star nearly due north about one fist -held at arms length – from M44..

Your fist held at arms length covers about 10 degrees – just a bit more than the distance between the Beehive and Iota Cancri. (Prepared from Starry Night Pro screenshot.)

This is one of the doubles featured by Guy Consolmagno and Dan Davis in their beautiful observing guide, “Turn Left at Orion.” The primary is a giant and while the two stars are gravitationally linked, they are quite far apart as doubles go. (Almost as far apart as the real Albireo and a bit farther apart than what others call the “Winter Albireo.”)  Consolmagno and Davis note that if you were on a planet that orbited the primary star, you”would see its companion as a very bright star, about half as bright as the Full Moon. ” From a planet orbiting the secondary, the primary “would look about four times brighter than the Full Moon.” I love to carry images like that in my head to the telescope and ponder them as I observe.

But I’m getting side tracked.  See, Iota Cancri looks so much like Albireo to me that I have written “Winter Albireo” in the margins of two of my observing books next to the Iota Cancri entry.  When I saw those notes as I was planning this observing session, I assumed that was it’s accepted nickname – wrong!  Seems like the only one calling Iota Cancri that is me. Or at least I can’t find any other reference to it as such.   What I did find, as I said, is that another double I’ve never seen is called the “Winter Albireo” by many  others and is generally regarded as too frequently neglected. Well, mark me down as “neglectful” – I’ve never seen Herschel 3945, but now I am really curious, so it has moved to the top of my “to be observed list!” And when I do observe it I may change my tune, but from what I’m reading I just don’t see how they give it this nickname while ignoring Iota Cancri.

I love Albireo. Nothing can replace it. My observations of it go back nearly half a century and I’ve never tired of looking at it. I always see it as gold and blue – very easy to split and with dramatic contrast.

And when I looked at  Iota Cancri  on this occasion I saw a wonderful yellow – pale yellow – primary and a beautiful, deep, sky-blue secondary. So I will readily admit that my idea of the “Winter Albireo” doesn’t quite measure up to the summer one, but it comes close.  I confirmed this by getting a couple hours sleep, then getting up and observing the real Albireo while the memory of Iota Cancri was still fresh.

So when I got in to write this report I decided to check on the spectral types to see if that gave me a solid guide to these color differences.  Guess what? It does – but it opens more questions.  The Albireo primary is a K3, the Iota Cancri primary is G7.5.  Look at the chart in the Star Colors post and you’ll see that  we tend to perceive G stars like Iota Cancri as “yellowish white.” Whereas K stars, like the primary of Albireo, tend more towards the orange.  So “pale yellow” for Iota and “gold” for Albireo seem to fit. The secondary’s also match the spectral classes. The Albireo secondary is B8 and the Iota Cancri secondary, A3 – that makes the Albireo secondary a somewhat richer blue, but they both tend towards blue.

Yes, this is splitting hairs because colors are so difficult to perceive, but having observed them within a matter of hours of one another, I did come away with just that impression – Iota Cancri makes a credible imitation of Albireo, but in the end Iota is just not as intense.

And what about the star so many do label the “Winter Albireo?” There my curiosity is really sparked.  The h3945 primary is a K0 – so that pushes it over closer to the yellowish-orange of the real Albireo primary. So far so good.  What throws me, though, is the spectrum of the secondary. It is listed as F0! That puts it in the white category in terms of our perception – or certainly a very,very pale blue. Not nearly so blue as the B8 of Albireo, or the A3 of the Iota Cancri secondary.  These deductions based on spectral class also match the description in “Turn Left at Orion.”

Herschel 3945 gets attention under the “Also in the neighborhood” category of “Turn Left at Orion” – just not the neighborhood of Iota Cancri.  They link it with observing an open cluster, NGC2362, in Canis Major.  They note that the primary is a “distinct red, while it’s companion may appear white or yellow.” Huh?! Does that sound like Albireo to you? Red and white/yellow?  What happened to gold and blue? I find their description in tune with the spectral classification, but out of tune with Albireo.  Still, they note that this double  is more popularly known as ‘The Winter Albireo.’  Indeed the color contrast and separation are reminiscent of Albireo…” Oh boy! Color contrast maybe, but not color. Now I really have to get a look at these stars!

So I’ll report back here after I’ve looked at h3945 and we’d love to hear from others on how they see these three stars. Here are the vital statistics for each.

Beta Cygni

19h 30m.7

+27° 58′

3.1, 5.1

34.4″

54°

K3, B8

Iota Cancri

08h 46m.7

+28° 46′

4.2, 6.6

30″

307°

G7.5, A3

h3945 (Canis Major)

07h 16m.6

-23° 19′

5, 5.8

26.8“

52°

K0,F0

Just looking at the stats, they do all look pretty similar until you get to spectral class and in that  I would think Iota Cancri would be a  better match.

And h3945? How does Sissy Haas see it? Well, she reports the stars “are bright citrus orange and royal blue: the colors are seen vividly and in strong contrast.”

And, of course, we have discussed many times  the variables involved in seeing color differences – but there may be something special here in h3945. I can’t wait to see for myself.

Update: March 12, 2011

Conditions certainly could have been better, but seeing was just a bit below average and I found a hole through the bare tree branches where I had a clean shot at h3935 and guess what? It’s every bit as  beautiful as folks say – but in my book it is not the “Winter Albireo.” In fact, the colors remind me more of Rasalgethi  (Alpha [α] Herculi) – orange going to red with a blue companion. I think one thing that separates it from Albireo, besid the colors, is the primary just isn’t as dazzling. With Albireo you’re seeing  a magnitude 3.1 primary, whereas  h3945 is nearly two magnitudes fainter.

I would also say that I’m looking through a lot of atmosphere – I caught it when it was about 24 degrees above my southern horizon which is only a couple degrees lower than it is at transit, so I can’t do much better. I suspect that contributes to the redness  however. Folks in the southern states  have a better shot at this beauty. I used the Televue 60 with a 10mm Tak for 36X which to my taste gave very nice proportions.  It was just as attractive in the TV85 with a 13mm Nagler – 46X.

Want to take a look for yourself? Here’s a finder for the “Winter Albireo” aka. h3945.

Look for the triagle of bright stars south of Sirius. Atsra with Adhara and go to Wessen – consider that one step. Continue moving inthe same direction the smae amount (about 3.5° – and you willfind yourself at h3945.

Now that said, the overall impression of the true ALbireo in a 60mm scope at 72X left me duly dazzled  – and smiling broardly at the winter imposter. Oh Iota Cancri is nice. It is wonderful, really – it just isn’t Albireo. But it’s a darned good substitute on an early Spring evening.  Hmmmm. . . and maybe that’s the solution. When I made this observation it was still winter and Iota was well placed at a reasonable hour.  So i guess that makes it a winter star. But I have to admit, it feels more like a spring star. So maybe I should give the Big Dog his “Winter Albireo” regardless – and give the Crab a Spring Albireo!

6 Leonis – an orange with a violet puff ball as viewed from an icebox

Finding 6 Leonis was a minor affair, though the weather made it more interesting. The temperature was 18° F and the wind was reportedly gusting to 50 mph, though it seemed more like 15-20 to me, so I expect those 50 mph gust were rare. But we had just had a blizzard and several inches of frozen snow was on the ground and deck – in short, conditions were absolutely perfect – perfect, that is, for trying out my new heated “Tempachair” that Bren had found and given me for Christmas – what a neat surprise! So here’s what winter observing looked like at 4 am this morning.

That's an 80mm Orion Short Tube on a UA MicroStar mount which is on a Bogen 3036 Tripod with the adjustable center post. But what you can't tell from this photo, is the chair is heated - a key to this creature's comfort 😉 Oh - hot tea is in the insulated mug and books and things are in the pockets that hang off the left side of the chair.

But first let’s talk about a nice little double, 6 Leonis. Here are the bare facts:

6  Leonis aka Sh107
RA:  09h 32m   Dec:  +09° 3′
Magnitudes         A: 5.2    B: 9.3
Separation          37.4″
Position Angle    76°
Distance:  483 LY
Spectral Classification: K3III

Haas calls this a “lovely brick red star with a faint dot of light wide beside it.”  Webb has it as “deep orange, green.” Uh huh!  Can I take one from Haas and one from Webb? I would agree with the “deep orange” of Webb and with the “faint dot of light” Haas uses.  Well, I saw the secondary as a “violet puff ball,” but only when I cranked up the power. Truth is, I came darned close to not seeing the secondary at all. I was using the Orion Short Tube 80 which despite the F5 focal ratio and lousy seeing was giving me a pretty clean image of the primary at 66X – the 6mm click stop on the Nagler 6-3 zoom.

However, the secondary at that power, was barely detectable. Now there was a last quarter Moon in that region of the sky (about 45 degrees away)  offering some competition, but an 80mm should dig out a 9.3 magnitude star pretty easily and the separation here is wider even than that of Albireo and its companion – though there are four magnitudes difference between the two and I guess that can account for the problem. Even when I doubled the power going to the 3mm click stop the secondary kept going in and out on me. This was one of those instances when I was glad I had noted the position angle in advance. Knowing where to expect to see it helped. The funny thing was, when I saw it, I really saw it quite clearly, then it would drop out entirely for a moment or two . The “Night Sky Observer’s Guide” has the secondary at 8.2.  I favor the 9.3 in the Haas book. I’m sure an 8.2 mag star would not have given me this much  trouble.

Finding 6 Leonis is relatively easy, though I managed to make it a bit difficult on myself. Essentially, I started with Regulus because 6 Leonis is about 10 degrees to the southwest.  Hopping from Regulus to Omicron, a mag 3.5 star that you should be able to spot with your naked eye, is easy and you’re almost there. A little bit farther to the southwest are three mag 5 stars in an arc and 6 Leonis is the middle of the three = or so I told myself having looke dat the chart. Trouble is, when I got outside I found there were four stars, not three  – the fourth slightly fainter and breaking the arc pattern. This threw me off so I kept trying to split the wrong star at first!  What I should have looked for instead of the arc of three, was a four-start “lightning bolt” with 6 Leonis the second star from the “top” – north. Here’s a chart that should make it clearer.

Star hop from Regulus to Omicron Leonis to 6 Leonis - second star in a four-star lightning bolt. (Slightly modified Stellarium screenshot.)

OK – about that chair. I like it. It is rugged, it is light,  the arm-tablet is useful to hold drink and eyepieces and the largest pocket holds the “Pocket Sky Atlas.”  The heat is supposed to work on high for two hours and on low for four. I wouldn’t know. In those temperatures I don’t function that long. The battery is rechargeable form AC or a car battery. Keeping in mind a near zero windchill I would call the seat comfortable. It certainly wasn’t hot – but it wasn’t cold either – then again, my insulated mug could hardly keep the tea warm for 15 minutes under those conditions.

Putting the scope on a tripod with an adjustable center post means you can observe sitting down in real comfort adjusting the height as you change targets.  Me, I wanted to check out that new storm on Saturn John had told me about – but Saturn was in the trees, the branches were blowing in the wind, and I really didn’t have enough scope set up to do that – I tried, but to no avail. So I switched to the last quarter Moon and was instantly rewarded with a beautiful sight! Four peaks of the Lunar Apennines were marching through the terminator and into the dark lunar night  and arcing down to meet them – a long gap inbetween – were a couple peaks of the Lunar Alps.  I stopped the ShortTube down to 42mm and just sat and enjoyed the view. I really didn’t want to go in despite the cold. But while my bum was warm, my hands were freezing. Being overly thrifty when it comes to using chemical handwarmers, I had not used any because I thought I was going to be out for just 20 minutes. With handwarmers I think I would have stayed out for another hour. Goregeous night despite the  conditions. But anyway – 6 Leonis was a fun find    and having a warm seat certainly helps.

Algieba – a new star for the Dolphins!

That’s the Miami Dolphins football team – they could use a new star this year – but that’s not my department. My department is trying to  describe the elusive and  lovely colors of γ Leonis, aka Algieba.

Algieba – Gamma (γ)  Leonis
RA:  10h 20m   Dec:  +19° 51′
Magnitudes         A: 2.2    B: 3.5
Separation          4.4″
Position Angle    127°
Distance:  90 LY
Spectral Classification: K0/G7

A few mornings ago I was sitting in the glare of a nearly full Moon, looking at Algieba for the umpteenth time and wondering how I would describe the colors I was seeing and the Dolphins distinctive orange and green leaped into my head. At least that was how they struck me with the 8-inch Celestron EdgeHD under average – maybe  a little below average –  seeing. With a 60mm F13.3 Tasco I  had more trouble seeing the color. The orange tint was there for the primary – but I think the green was in the secondary primarily because it was already in my head from the view with the larger scope!

My difficulty in picking up the color this time may have been due in part to the glare from the Moon because usually these colors jump out at me. Actually, as I think about it these colors may be more impacted by the Moon light than those of other stars because these aren’t real – or the green certainly isn’t.  Well – it’s real enough to me and selected other observers, but as the “The Night Sky Observer’s Guide”  by Kepple and Sanner explains, the two stars are really deep yellow and pale yellow. “Some observers have reported the companion to be greenish – but that is at least in part an optical illusion caused by the contrast of the deeper yellow of the primary with the paler yellow of the secondary.”

The “apparent color” of a K star is “yellow orange” so that roughly fits my description for the primary. But the green of the secondary? A G star should be yellow. ( See the chart in this post on Star Colors.)  Sissy Haas apparently used a 60mm and writes: “A brilliant figure 8, slightly unequal, grapefruit orange in color.”  She quotes Smyth as describing the stars as “bright orange, greenish yellow” and Webb as “Gold, greenish red.”  Oh boy! So the green business is persistent, but not entirely consistent! What do you see? This one is really in the eye of the beholder, but beautiful however you describe it.

Algieba is easy to find. It’s a second magnitude star about 8 degrees north of Regulus in Leo’s sickle. (Screenshot, with labels added, from Stellarium.)

It is simple to find and not a difficult split. To find it, look for the second star up from Regulus in the sickle of Leo.  I know I have the right star when I look in the finder or low power eyepiece because 40 Leonis, a 5th magnitude star, is less than half a degree south of Algieba at about PA 189°.  And since the PA for the secondary is 127° this give you a rough guide as to where to look for it. (If sky directions and position angles confuse you, see this post.)

I split it easily with a 24mm Panoptic (83X) in the 8-inch SCT. I liked it best in that scope with the 13mm Nagler (154X). I also had no trouble getting a clean split with a 60mm refractor. That done I was encouraged to try again with the 50mm Little Rascal. The night I did most of the tests on that scope for this post I wasn’t able to split Algieba with it.  But on this particular morning – the one after the lunar eclipse –  I did split it nicely using the 3mm click-stop (68X)  on the 6-3 Nagler zoom.  This meant seeing was better than I first thought – so I went off  to try Porrima with the 8-inch. I really would like to get a pristine split of that pair!

It had been hopelessly cloudy  here for the total lunar eclipse on December 21, 2010 so, of course, the next night it was  brilliantly clear and I marveled at the brightness of the snow-covered landscape reflecting the just-past-full Moon’s light as I approached my small observatory. When I emerged from it a while later – I had no real luck with Porrima – I was brought up short by clouds near the Moon. Yes, I’m conditioned to abhor clouds – but these were gorgeous. Light, stranded ones sailing in from the northwest and all shining brightly in the moonlight. It was a Christmas scene out of Currier and Ives. Home,  fir trees, snow on the ground, friendly clouds above and the Big Dipper high over head with Venus, fairly screaming for attention as it rose  in the southeast and shone through the bare trees in my neighbor’s woods.

You split some, you don’t split some, but you always win just to be out on nights such as this.

Note:  A few mornings after this I was out with the 50mm F12 Tasco to tackle Mizar and once done, I took on Algieba and then Castor again. On Algieba I got a split with the 10mm Tak Le, but it was much better with the 7.5 and it wasn’t until I put in the 5mm (120X) that the colors really came out.

Glowing in gold, and always a glorious sight to behold! (Click for a larger view).

The Lion’s double double – Tau and 83 Leonis

Tau (τ) and 83 Leonis are a charming pair of pairs in Leo just a bit west of  where it borders Virgo and not very far away from the fabled Porrima. Though it has neither the magic nor the challenge of the Double Double in Lyra, it’s fun  to track down and very rewarding in its own right.  I was able to split these pairs easily, first using an 8-inch SCT, then the next night using a 50mm Stellarvue “Little Rascal” at 20-40X.

Tau (τ)  Leonis aka Σ119
RA: 11h 28m   Dec:  02° 51′
Magnitudes: 5.1, 7.5   Sep: 88.9″   PA: 181°
Distance:  621 LY   Spectral Type: G8II-III

83  Leonis aka Σ119
RA: 11h 27m   Dec:  03° 01′
Magnitudes: 6.6, 7.5   Sep: 28.6″   PA: 150°
Distance:  58 LY   Spectral Type: G7V

This was an enjoyable star hop that started with Denebola,  the second magnitude star that mark’s the Lion’s tail. You can be sure you have it in your finder because there’s a sixth magnitude star just 20 minutes south of it.  In fact, use this companion as a guide – it’s pointing you in the right direction.  Tau is going to be about 12-degrees along the line between Denebola and it’s companion – a bit more than two finders fields for me.  When about half way to Tau you should encounter a distinctive trio of triangles. This was a marker for me that told me I was on the right track – like hopping from stone to stone across a brook, this was the big, flat, stone in the middle where you could pause to catch your breath and take your bearings.  It looks like this:

Three triangles in Virgo as seen in a correct image finder. Click image for larger view. (Prepared from Starry Nights Pro screenshot.)

Nu Virginis is magnitude 4, Omega magnitude 5.  Treat Omega as the tip of an arrowhead and it’s pointing you right towards Tau Leonis. When you get in the vicinity, here’s what the typical correct image  finder should reveal. (Notice we started in Leo with Denebola, crossed the border into Virgo where the three triangles are located, then hopped back over into Leo to find the two doubles, Tau and 83 Leonis.)

Binocular or correct image finder view of the Tau and 83 Leonis region. (Developed from Starry Nights Pro screenshot.)

Here’s the view in a Celestron EdgeHD SCT with  a 30mm Take LE eyepiece that gives a field of  view of about 47 minutes, this view from Starry Nights Pro does a good job of approximating what I saw.

Tak 30

The widefield view has a certain charm. It’s not at all like the uniformity of the Double Double in Lyra where the stars are about equal in brightness and the split of each pair is baout the same. Here the two secondary stars in each pair are the same brightness, but the primarys differ and the split differs significantly, though both are wide and easy, especially in the 8-inch. They jump out at you, but I checked the PA just to be positive I had the correct stars.

I examined both pairs more closely in an 18mm Tak at about 111X.  In both cases the colors seemed obvious to me. Tau was a lemon yellow and pale blue.  The closer pair – 83 Leonis – showed pale yellow and pale violet. Sissy Haas describes the colors this way:”a yellow-white star and a lemon-yellow star – each with a small grey companion.”  Well – at least we agree ont he shades of yellow – and”gray” isn’t that far off from the pale blue and violet that I saw.

Will I come back? Yes. Matter of fact, I’ve been here before. I made a notation in the Haas book – “5/2/07.” That means I saw it then – but I wish I had written a complete report. Sometimes I really spin my wheels. But then, so what?  I don’t remember the earlier observation,  so I  get the thrill of discovery twice this way ! Got to be some advantage to growing old  😉

Σ178: Ram’s Eyes Lite? And just a quick slide down the declination axis away!

I’m sure you can star hop  from the well-known Ram’s eyes to what I would call the “Ram’s Eyes Lite”  – but if your scope is on an equatorial mount life is much, much simpler. All you need to do to mine this pair of evenly matched, 8th magnitude gems is take a quick slide down the declination axis.

Why “lite” – well look at how nicely the numbers compare – in bold are the numbers for the Rams Eyes Lite as compared with Mesarthim -γ  Aries -the original Ram’s Eyes .

Ram’s Eyes             vs  Σ178: Ram’s Eyes Lite
RA: 01h 53.5m                               RA: 01:52m
Dec: +19° 18′                                  Dec: +10° 49′
Mag: 4.5, 4.6                                   Mag: 8.22, 8.20
Separation: 7.5″                               Separation 3.4″
PA: 0°                                                 PA: 204°
Distance: 204 LY                             Distance: 413 LY
Spectral Classification: B9, Ap      Spectral Classification: F1V

OK – maybe you have to study the numbers a bit to see the connection. The Lite version, for example, is far, far dimmer – BUT, the stars are nearly identical in brightness, as are the Mesarthim twins – and that’s what makes both pairs into “eyes.”  Separation, I grant you, is quite different. The fainter stars are twice as close.  But don’t be fooled by the PA. It’s hard when looking at nearly identical stars to decide which is the primary. But with a PA of  0° the Ram’s Eyes line up perfectly on a north-south axis. And, with a PA of 204° the Ram’s Eyes Lite  line up pretty much north south also – well, they favor northeast to southwest a bit, but just a bit.

To find Σ178 start by locating the three brightest stars in Aries. (Developed from Starry Nights screenshot.)

But the most useful similarity is in their Right Ascension – notice they are within less than a minute of one another? (Mesarthim – RA: 01h 53.5m      Σ178 -RA: 01:52m) That means that with an equatorial mount you simply lock onto the very easy to locate Ram’s Eyes (Mesarthim) and having enjoyed that view, just slide down the declination axis about 9 degrees and you’ll be on  the Rams Eyes Lite.

Next, head due south from Mesarthim. (Developed from Starry Nights screenshot.)

Now you can do that all by the numbers, or you can do what I did. I used the following image of the star fields for Struve 178 so I knew what to look for – then I just locked my RA once on the Ram’s Eyes and slid south until I spotted this star field – centered the double, and started cranking up the power. And if you’re star hopping? I suggest you make sure you know the size of your finder’s field – it takes a six degree field to capture the three bright stars of Aries in the same view, so that’s one way to estimate your field. Then all you have to do is know which direction in the sky is south and move about 1-2 finder fields from Mesarthim until you encounter 4th magnitude Omicron Piscium. Treat that as a stop sign. With it at the southern edge of your finder you should see something like the  view that follows. (If directions in the sky – not to mention position angle – leave your head spinning, try the tutorial here.)

Look for this distinctive star field where Σ178 is in the middle of one side of the triangle. (Developed from Starry Nights screenshot.)

When you do find it I must admit it was a bit much for my 60mm refractor with seeing below average. In the 8-inch SCT it split easily, but not in a satisfying fashion. Again, the seeing i the culprit. I’m looking forward to revisiting.  I’m sure on a better night it will split easily witht he 60mm, but probably look best in the 80mm, or maybe the 110.

41 Aurigae and a serendipitous bucketfull of Sighs!

Serendipity – don’t you love it? That’s the main reason I enjoy star-hopping so much and have long-since sold my GOTO scopes. In this instance my curiosity was first raised by what I saw in the sky, then really pinged by what I saw on the charts. But first, our subject star:

41 Aurigae
RA:  06h 12m   Dec:  +48° 43′
Magnitudes         A: 6.2    B: 6.9
Separation          7.6
Position Angle    357°
Distance: 310 LY
Spectral Classification: A1V, A6V

Sissy Haas rates this a “showcase pair” in a 60mm. It’s nice, but I couldn’t get that excited about it, perhaps because I was overpowering it with the new 8-inch SCT, a Celestron EdgeHD. But as I said, I enjoyed the prowl in this section of sky. If you picture Auriga as a kite, you can start your journey towards 41 at the top (north end)  of the kite with second magnitude Menkalinan. From there it’s about 6 degrees northeast.

41 Aurigae correct image finder created from Starry Nights Pro screenshot.

The first thing that caught my eye in the finder was Pi – I use a correct image one most of the time, though this time I was using the  straight through finder that came with the EdgeHD.  This finder seems to be particularly good and Pi was so red I thought it might be a carbon star. However, when I got back in the house and looked it up it turned out to be an M-class Bright Giant. Not bad! Very red and quite beautiful from its perch about 800 light years away.  From Pi it was  a simple star trek over to a little trickle of sixth and seventh magnitude stars that took me down to 41.

In the 30mm Tak it split nicely, but it was best in an 18mm. My notes say “blue and pale apricot” – sounds delicious.  However, Sissy Haas says it’s a “pair of yellow-white” stars. Smyth  has them as silvery white and pale violet. Oh boy!  Yes, I was looking at the same star. No doubt. So I have no explanation for my radical color difference. Smyth’s colors seem closest to the spectrum classifications.

That aside, while looking in the finder I became fascinated with a star a bit farther to the east, and when I checked the Chart 3 in the “Cambridge Double Star Atlas” I saw it was labelled “ψ1” – Psi 1. Hmmm. . . wonder if there is a Psi 2? Wait a minute! Off to the east is another Psi – but this one is Psi 6! One and six? What is this?  And as I looked more I saw there was a whole gaggle of them – ψ7, ψ9, ψ2, ψ4 – and no order that I could see. Sigh- a whole bucketfull of Sighs.  I couldn’t remember a similar example anywhere, so what the heck was this?  And that puzzle resulted in some armchair prowling which turned up this little serendipitous discovery – I was looking at  an extinct constellation created to honor one of my favorite astronomers, William Herschel, for his discovery of Uranus! What’s more, it turns out to be a classification of stars I’ve never seen before – a “star system.” As I understand the definition a star system is an open cluster wannabe! It just doesn’t have enough members to be given that more common designation.

Herschel's telescope from the Bode atlas of the time.

But I’m more fond of the old constellation that no longer appears on our charts – Telescopium Herschelii! isn’t that cool.

Maximilian Hell created this imaginative gem in 1789 and squeezed it into the star system  found in a corner where Lynx, Gemini, and Auriga meet.

I doubt I’ll ever be able to form those stars into a telescope, but what the hell 😉  Next chance I get I am taking my binoculars and looking for this “star system” and when I find it I will pause and remember Herschel and how he doubled the size of our solar system. In fact, I had just been writing about Herschel’s “Georgian Star” here, so it is fresh in my mind. As I say – serendipity. It goes hand-in-hand with star hopping. Sigh!

Meanwhile, back in our galaxy – Σ79

In November who can resist M31, the Great Andromeda Galaxy, high in the east?  But when you exhaust yourself from all that travel – afterall, even at light speed we’re talking 2.5 million years on the road  – you can return to “home” by sauntering over to Σ79, a wonderful little double about 4-5 degrees northeast of Andromeda and right on a line from the great galaxy to fourth magnitude Phi Andromeda.

Σ79
RA: 1h 00.1m   Dec: +44° 43′
MG: 6.0, 6.8   Sep: 7.8″   PA: 193°
Distance: 420 LY
Spectral Classification: B9.5V, A2.V

That said, I didn’t find Σ79 as easy to find as the description implies.  This is a pretty busy section of sky and part of my problem was I was using M31 as a pointer, telling myself that all I had to do was go roughly north along a line suggested  by the longer axis of M31.  It looks obvious on the charts and I thought it would be obvious in the scope, but finding that longer axis precisely  in the scope proved more difficult than I anticipated. As a result I was looking a bit west of where I should be and targeting the wrong sixth magnitude star and wondering why it didn’t split! In fact I did that more than once because there are four magnitude 6 stars within about two degrees of Σ79! I think I tried to split each one before I finally settled on the one farthest east – the correct one.

What I should have done is gone northeast from Andromeda – technically the PA from M31 to Σ79 is 41° –  and what would have helped immensely is to just draw a line between the galaxy and fourth magnitude Phi Andromedae.  Σ79 falls just east of that line about three degrees south of Phi and almost five degrees northeast of M31.  Here’s a chart from Stellarium that should help.

Click on image for larger version. (Prepared from Stellarium screenshot.)

When scouting this region with 15X70 binoculars I picked up a wonderful cascade of 7th and 8th magnitude stars just to the north, while a shorter cascade actually leads to Σ79, though I didn’t realize that at the time. It really does pay to study – not just glance at, but study – the charts in advance. Would have saved me some time – but then, time prowling a starry sky is never relly wasted 😉

So – arriving at Σ79 my color imagination was working overtime and I saw a wonderful primary I pegged as pale yellow and a secondary I felt was violet. Haas has them as “pearly white and pale blue-violet” in heer “double stars for small telescopes” book.  I have to admit, her colors certainly fit the spectrums better than mine. Not sure where that yellow came from. I was using a 127mm Meade AR5 achromat with a 24mm Panoptic and got a delicate split at 49X. The view was much more satisfying with a 13mm Nagler (90X).  However, I enjoyed the view in the 60mm Tasco better – the power drops to about 42X when using the 24mm Panoptic in this old F16.7 achromat, but the view is one to kill  for – especially with the 13mm Nagler. OK – that’s a judgment call.  I always love the view in the 60mm as long as the doubles are bright enough, and int his case they produced two, absolutely clean, bullet holes in the velvet blackness of night – side-by-side and close, not just in spacing, but in brightness.  I love it!

In fact, I got so enthusiastic about the view in the 60mm I had to push my luck and try the 50mm Stellarvue Sparrow Hawk I was using as a finder. It’s fvertyf ast – about F4 – and I got 40X out of it – about its effective maximum –  by using a 5mm Tak LE. Pristinely delicate and absolutely charming!

OK – maybe seeing was especially good. Maybe I’ve just looked at too many double stars. I’m not at all sure this would have thrilled a visitor to my little observatory. Heck, I’m not sure they even would have seen the split.  But it’s the sort of thing I really enjoy. Σ79 is a keeper. I like the region. And it blows my mind to be looking one moment at a few hundred billion stars 2.5 million light years away, then barely moving your scope to zoom in on something a mere 400 light years away. Those are the sorts of things that keep me coming back to a double like Σ79.