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Pi 1 Ursa Minoris anchors an equilateral triangle inside a not-so-equilateral triangle

Pi 1 Ursa Minoris –  RA: 15h 29m   Dec: +80° 27′ MG: 6.6, 7.3  Sep: 31.7″   PA: 78  Spectral Type: G0, G8 subgiants Distance: 71 light years

Hmmm . . . I should be able to say something more about this easy double than that it’s a triangle inside a triangle – afterall, wherever you find three stars you can find a triangle of sorts. But John has been threatening lately to find doubles inside Ursa Minor and when he got distracted by other things, I decided I would take a look. Guess what? there are slim pickings here – especially for a 60mm. Sissy Haas lists only six doubles in Ursa Minor and uses a 60mm on only two, one being Polaris. Polaris, of course, is an exception, but it’s a challenge object for a 60mm, not, in my book, a “60mm jewell,” though it certainly is a gem in a larger scope. 

Pi 1 is not a challenge. You should be able to split this little dude with anything – even a telescope you got as a prize in a Crackerjack box! And in a 60mm, it’s actually quite satisfying. Hey, I’m going to call it a very subtle violet and green, though I suspect others see it as white and, uh, sort of white. (Yep – that’s what Haas says, though it’s spectral class might suggest a bit of yellow. Maybe “sort of white” is right.)

It’s also in a kind of fun area to explore. Start at Zeta –  that’s the fourth magnitude star that anchors the cup of the Little Dipper to the handle, then draw a mental line northward to the  next star in the handle, Epsilon.  Half way between these two, and a bit to the west, is a nice grouping of stars in the 6th-8th magnitude range. (Careful –  there’s a nice group of stars to the east also.) Part of the Pi group includes a triangle of 7th magnitude stars that fits nicely inside the 2 degree field of my 32mm Plossl when used on the 60mm Unitron (28X). And inside this triangle is a second, smaller triangle of 7th magnitude stars and this one is equilateral with its southern most corner being the double. But you don’t have to figure out which corner is to the south – just look for the double. The stars are pretty closely matched (6.6 and 7.3) and split by 32 seconds – a bit more than Albireo!

Wikipedia says this pair also has  an 11th magnitude companion, 135″ away. Didn’t see it. Well – didn’t look for it. Maybe another time.

Bet this field would make a nice sight in the 20X80 binos – have to give that a try!

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2 Responses

  1. Got a chance to give the 20X80 binos a try on Pi 1 last night – transparency was to Mag 5 and this field was indeed beautiful. I could split Pi 1, but I forgot to look for the 11 magnitude companion -probably would have been on the edge of visibility in any event. But i want to return to this region in particular and the whole area in and around the cup of the Little Dipper using the 1 20X80s. There are lots of nice star fields here.

  2. Easy as Pi? Not tonight it wasn’t. I’ve had this on my list of stars that I wanted to get a look at it for quite some time. With the full moon low in the south tonight, my goal was to get as far away from it as possible. So this was the night for Pi-1. There was one problem, though – I had re-mounted my finder on the 76mm scope I was using, and somehow had managed to line it up on the wrong star. Chalk it up to too much lunar luminance, and mark it down as stupid scope trick number twelve. At any rate, the result was that I was aiming high and missing my goal completely.

    I was trying to line up on a point midway between and slightly to the west of Epsilon and Zeta Ursa Minoris, but as a result of the glow from the moon, I could barely see either of the stars visually. Every time I pointed the scope in the approximate vicinity, and then moved the finder to two bright stars that looked like Pi-1 and Pi-2, I was ending up on the east side of the line between Epsilon and Zeta in the area Greg refers to above.

    So after realigning the finder on the moon, I took a break. As I was brewing a cup of tea and getting something to eat, I decided to give the setting circles a try. Engaging the brain that had been out to lunch when lining up the finder, I looked up the coordinates for Kochab (Beta) and Pi-1.

    Back outside, I centered Kochab in the eyepiece of the scope. On most old scopes, the RA circle just will not move, and that was the case on the old Tasco 76mm, so I decided just to use the right ascension circle as a reference point. The RA for Kochab is 14h 51m, and for Pi-1 it’s 15h 29m. So I moved the scope east 40 minutes. Now the declination for Kochab is +71 degrees, 9 minutes, and for Pi-1, +80 degrees, 27 minutes. So straining my neck to get under the tube in order to see the pointer on the declination circle, I moved the scope north nine minutes, held my breath, and looked in the finder.

    Bulls eye! There was Pi-1 and Pi-2, not quite in the center of view, but there nevertheless. So, moving them to the center of the field of view and holding my breath again – because I had been fooled too many times to count during the previous hour – I cautiously peered in the eyepiece – and YES! – one fantastic close pair of stars with a position angle of about eighty degrees – just like the book said!

    Now, you have to put things in to context to properly understand them sometimes. Greg was more restrained in his description of this pair of stars. But for me – who had been at this for going on an hour and a half now – the experience was like coming across an oasis in the middle of the desert after a week without water!

    I restrained myself from yelling “There they are!” because it was two in the morning and the neighbors probably wouldn’t share in my enthusiasm after being awakened from a dead sleep. But it was pretty close there for a few moments. And yes, it doesn’t take much to give me a thrill. But I like it this way.

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