RA: 20h 09m Dec: +77° 43′
Mag: 4.4, 8.3 Sep: 7.2″ PA: 120°
Dist: 330 LY
Spectral Classification: B9
RA: 21h 39m Dec: +57 29′
- AC – Mag: 5.7, 7.5 Sep: 11.7″ PA: 120°
- AD – Mag: 5.7, 7.5 Sep: 19.7″ PA: 339°
Spectral Classification: O6
RA: 21h 40m Dec: +57° 35′
Mag: 7.4, 8.6 Sep: 12.7″ PA: 59°
Spectral Classification: F5
RA: 21h 28m Dec: +70° 34′
Mag: 3.2, 8.6 Sep: 13.2″ PA: 248°
Spectral Classification: B9
Delving into the rather faint circumpolar constellation of Cepheus, I was frustrated by my first doubles target, then challenged, but wonderfully rewarded, by the next. See two of the stars listed above – Σ2816 and Σ2819 – are respectively a triple and double and not only are both in the same field – a very rich field – but their neighbor is the gorgeous “Garnet Star” discovered by William Herschel. All of which made splitting the last star on this short list a sort of anticlimax – it deserved better! but I’ll report them in the order I did them.
First up was Kappa Cephei which I thought would be a challenge, but not nearly so difficult as it proved to be. I was using the Unitron 114, a 60mm scope and I thought this would be somewhere in the ballpark of Polaris as difficulty goes. Consider that the split at Polaris is significantly wider – 18.6″ – but then we have a difference of 7 magnitudes! With Kappa there is only a difference of 4 magnitudes, but the split is less than half that of Polaris at 7.2″ – still well within the capability of a 60mm. or so I reasoned. I should have noted that while Haas rates this a “showcase pair,” she also list the instrument used to split it as 125mm. Oops. But conditions were far from ideal and I was a bit sleep-deprived and I’m also a bit concerned that the Unitron’s optics aren’t all I assumed they were. Here’s why.
I kept thinking I could see the faint companion – but I was putting it at the wrong position angle. The PA is 120° according to a couple reliable sources – and my own later observation – but what I was seeing was over in the next quadrant – something more like 220°! I think what I was seeing was a fragmented Airy disc. That is, the diffraction ring was faint and split into three little chunks instead of making a complete circle. You need to know more about optics than I do to know what that means. But in practical terms it meant I thought I was seeing a faint companion star that wasn’t there.
The next night I got a lucky break in the weather – a thunderstorm went through and cleared out the July murk we had been experiencing – at least for a few hours. So I was out at 1 am in my comfy little observatory – the only place that was dry – and using the 8-inch SCT that happened to be installed there at the moment. That made short work of Kappa which is, by the way, quite easy to find. It’s pretty isolated from the five star asterism of a home plate that I always identify as Cepheus, but it’s a comfortable 10 degrees – one fist – from Polaris and reasonably easy to spot in dark skies. A good guide to finding it is to use Zeta Ursa Minor – that’s the 4.3 magnitude star in the corner of the Little Dipper’s cup where the handle connects. It’s the same distance from Polaris as Kappa and the three form a rough equilateral triangle. At 4.4 Kappa is just a tad dimmer than Zeta.
Haas reports a “brilliant peach white and a small powder blue, both of these colors seen vividly.” Sounds wonderful, but it just didn’t come across that way to me in the 8-inch. Nice – but I wouldn’t rate it a “showcase.” Then again, maybe I was just a bit jaded from my frustration in failing to split it the night before. I look forward to giving it another try with the 76mm Tasco and the 60mm Tasco. Meanwhile, I decided to go after a pair which she calls a “remarkable sight,” but doesn’t list as a “showcase.” I guess we all can’t agree. For me this was a really difficult field to find, but a delight when I did find it.
My problem here was I thought I could just star-hop with nothing but the Double Star Atlas in front of me and no real preparation. It didn’t work. There are a lot more stars in this section of Cepheus than you might think. This is, after all, the Milky Way. Deneb, for example, is just 15 degrees to the south. I figured I would just start at Alderamin – Alpha Cephei – and head southeast a bit until I bumped into that beautiful Garnet Star and I would be almost there – a little prowling nearby would certainly reveal it. Only it’s easy to confuse east and west in the circumpolar regions and I kept landing at bright stars that I thought were kind of reddish, but didn’t deserve the title “Garnet” and surrounding star patterns didn’t fit the charts. Then I’d find the Garnet str for sure, be overwhelmed by its beauty, and darned if I wouldn’t lose it again as I went looking for the triple and double. This is seat-of-the-pants star finding and after 50 years I’m a bit over confident and hate to admit I am lost – but I was lost!
It would have been another frustrating experience, except that this time I eventually found it and when I did I was delighted. This is surely worthy of the title “showcase!” Here is a beautiful, easy to split triple and just 19′ away a more modest, but easy to split, double. And they occupy a stunning star field – the open cluster IC 1396. So add it up! You get a terrific Garnet Star, a wonderful – and huge – open cluster – and you get a triple and a double. That’s more than wortht he effort. Granted, the Garnet Star is just a stop along the way, but I could spend a lot of time there – and did.
The Garnet Star – Mu Cephei – is a supergiant with a diameter almost as large as the orbit of Saturn, making it one of the largest stars known. It’s also a variable with a period of about two years in which it goes from 3.4-to-5.1. It’s about 2400 light years from Earth (according to James Kaler) and there’s a terrific photo of this star and region here. IC 1396 covers about three degrees of sky, but I did not notice – or look for – the nebulosity – just all the associated stars which make casual star hopping so difficult.
I love the triple. Not to get overly patriotic, but I saw it as red , white, and blue. Haas describes it “as a bright white star between a green companion and a violet one.” Color it anyway you like, it’s a gem. Can’t wait to check this region out in smaller scopes. I can’t get too excited about the double, but in the same field I suddenly felt a baseball metaphor trying to emerge because there are three stars in a straight line that dominate the field, a single, a double, and a triple! So consider the bases loaded!
Given the difficulty of the seat of the pants approach to finding this star, I’ve developed a strategy that is particularly useful if you have an equatorial mount – or so I hope. I plan to try this when I return to this region with smaller scopes. Here’s the plan.
- To find Struve 2816 I will first find second magnitude Alderamin – Alpha Cephei.
- Then I’ll lock down the RA – polar – axis and sweep five and half degrees to the south. ( I have an eyepiece that gives me a one degree fov, so this is easy enough to do.)
- Now I’ll lock down the declination axis, loosen the RA, and move three fields to the east. Bingo! If I’m right I should have both 2816 and 2819 in the same field, separated by about one third of the field. To see Herschell’s Garnet star, I’ll lock down the RA axis and pan one field to the north, then lock the Dec and pan east half a field. Piece of cake! (I hope.)
OK – here’s the preceding steps in visual terms.
When you get there, here’s what a one-degree field should reveal.
All of this is obviously a game of approximation, but it should put you in the right ball park and a little delicate panning one way or the other should reveal your target.
I at last let go of this wonderful region and moved on to an easy star – Beta Cephei. I was in the neighborhood and it’s supposed to be a real show stopper. Haas calls it a “bright pair that’s ideally close and easy” and suggests a 60mm at 25X. Since I was using the 8-inch i felt like I’d gone out hunting grasshoppers with a 50 caliber machine gun. Using a lot more scope than recommended doesn’t give you the same visual experience. It was too easy. Beta was real nice, but the charm was missing – and perhaps I was a bit satiated with my earlier experience. I decided I had to see Beta with the 60mm, but I had lost track of the time. Once I had the 60mm out and set up I was well into morning twilight, so I didn’t give it a try. I want to see this star as Haas saw it. So stay tuned. I’ll add to this report, once I’ve done that.
ADDENDUM: July 22, 2010 – 60mm Success!
Yes! Well, OK, partial success, but only because I didn’t have time to try everything.
What I did try was the Tasco 7TE5, which is a 60mm telescope of 1,000mm focal length on an equatorial mount. Again i got sudden, early morning clearing conditions – this time very transparent, but not very steady.
My first task was to find Alderaman (Alpha Cephei) simply by pointing the scope and recognizing it int he eyepiece -a little tricky in this crowded sky, but using the straight through finder with the scope pointed near vertical is beyond the kind of contortion my old body likes to do, so i cheated a bit. I looked at Alderaman in binoculars, noted the pattern of stars right next to it, and that way was sure I had the right starting point. I then followed my own directions, locking the RA and marching off to the south along that hour circle, then locked the dec and swung east and sur eneough there was – oops, there was the unmistakeable red glow of Herschel’s Garnet star. But that meant I was almost on target – just a tad north of where I should be – so I swept a little inthat direction and there was the star field I sort.
So this method meant I located my field in less than five minutes, rather than the 45 minutes it has taken me with seat-of-the-pants star hopping. Believe me, i don’t plan to do this for every target. It’s overkill and I just don’t do that much planning in advance. But I will use it when the path looks dicey.
And what did I see – gems, without a doubt – especially Σ2816, the triple. It is precious. A brilliant white dot with two pin pricks to either side. And while I can tell you the pinpricks are not white, I do have great difficulty deciding on any color. Perhaps at magnitude 7.5 it’s too much to expect the 60mm to gather enough light to make the color clear? In any event, I wavered and decided I have nothing to contribute on that score. I was first able to split both Σ2816 and Σ2819 with a 13mm eyepiece – 77X. I went on up to 100X, then decided it was crowding them too much. I then backed off all the way to 31X witht he 32mm Plossl. Yes, i could still detect the split – but the best view,f rom my perspective was with the 17mm – 59X. I plan to try again, though, this time with the 76mm Tasco.
There was a doll house feel to using the 60mm on these stars – as I say, charming. But I’m not sure a beginner would find it so. Idon’t think it would evoke the kind of “wow” reaction you get from a bright double in the 60mm, such as Almach or the Ram’s Eyes. However, i think somewhere between 60mm and 127mm is the perfect fit -a judgment call, of course, but something that makes the stars jump out at you and clearly reveals color. The 200mm C* I first used is a bit more than necessary. So i’ll be back!
I stayed with this field – and the garnet companion- for a good half hour or more, then gave a quick, half-hearted look for Beta Cephei. I wasn’t even sure I had the right star, but I decided the poor seeing made it too much of a challenge and I was eager to do some relaxed scanning with the 15X70 binoculars. I did and it was great. M31 seemed to fill the field, as did the Double Cluster in Perseus – and the North American Nebula was the best I’ve seen it. (All these subjects were high and I got to them in quick succession just as the morning astronomical twilight period was beginning. Found M33 as well and with no problem. Just leaped right out at me. This what the Starry Night Life is all about – the kind of nights that makes you forget any frustration you may have had in getting there.