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Ursa Major , laid bare !


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Stars of UMa.
Looking up and pointing out stars that have stories adds to the fascination of the night sky. 
Let's look at the stars of the "plough".

Dubhe (α) is a very wide orange and brown pair at low magnification.

Mizar and Alcor are optical doubles, the bright one , Mizar opening out to give a 14.3" split.

Talitha (ι UMa) shows a white and a close 4.5" blue, I found this quite a challenge.

Σ1523   (53 UMa, xi )(Alula Australis), a superb widening binary 1.7" at +4.3 +4.8 with an orbit of 59.8 years. This was the first ever binary discovered on 2nd of May 1780 by Sir William Herschel and the first visual double for which the orbit was found. 
To the north is Lalande 21185 a red dwarf +7.5 at 11h30.3m. +35 58'11". This is the fourth closest star and nearest planetary system at 8.32 lys.
Next door is Groombridge 1830 (Argelander's Star) the third fastest proper motion star , moving one degree every 511 years. At +6.4 go to 11h52.9m. +37 43'.

Some colours and showcases now,
Σ1193 shows a wide orange and blue at x50.
23 UMa shows yellow and green, there is a third element at 100" being +10.5.
Σ1415 shows a pair at 16.5".
Σ1495 between Merak and Dubhe shows an easy wide lovely pair.
h 2554 is a wide 40" with plenty colour here.
57 UMa a lovely white and blue at x100.
Σ1559 I use as a tester, a lovely delicate companion at 1.8".
65 UMa is a colourful triple , worth a long look.
Σ1603 gives a lonely pair of headlights at x50.
Σ1695 gives a lot of colour at 3.8". As does the blue companion of
78 UMa at a close 1.2".
Σ1770 , a most delicate pair, but I caught it in the 102. More colour at
Σ1795 at 7.9". I'll end with the very delicate 
Σ1831 an arc of a triple at x50.

All these were caught from the street lit edge of town. The only good thing about permacloud is going through old notes.

I found a scribble suggesting that the optimum magnification for observing binaries is 750 divided by the arc seconds. That combined with your maximum magnification being your aperture in inches x50, food for thought. Hopefully under the 
Clearest skies !
Old Nick.

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It's wide ! I have nearly completed those binaries detailed in the Book. Mostly using a 150 frac. I'm going back with a 102 and a 90 and starting off with some double star projects. I wish more folk would get into these , rather than chasing hard to see fuzzies from town !

old Nick.IMG_4189.JPG

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28 minutes ago, cotterless45 said:

It's wide ! I have nearly completed those binaries detailed in the Book. Mostly using a 150 frac. I'm going back with a 102 and a 90 and starting off with some double star projects. I wish more folk would get into these , rather than chasing hard to see fuzzies from town !

old Nick.IMG_4189.JPG

The main star (Dubhe A) is itself a double - it's a classic triple with the wide third component.

Chris

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I would do other stuff Nick if I was stuck in town...but fuzzy stuff means I have to drive through beautiful countryside to meet good friends, camp, drink, laugh and be away from the rat race for a weekend....tough call!

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On ‎21‎/‎11‎/‎2016 at 11:29, estwing said:

I would do other stuff Nick if I was stuck in town...but fuzzy stuff means I have to drive through beautiful countryside to meet good friends, camp, drink, laugh and be away from the rat race for a weekend....tough call!

When put like this it is quite irresistible :happy8: I was up in your neck of the woods yesterday Calvin and boy was it pouring down.

Great post Nick, its been a bit crabby here of late. Having said that some of the early hours have been pretty good though.

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"The main star (Dubhe A) is itself a double - it's a classic triple with the wide third component."

Yo Chris ! Its an eye watering .8" separation , snowman shaped is about it. The more distant companion is often overlooked. Will have another go next week. Was trying 36 Andromedae in the 102, nothing, then defocussed and the diffraction rings split wide open, way to go under,

clear skies ? Nick.

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2 hours ago, cotterless45 said:

"The main star (Dubhe A) is itself a double - it's a classic triple with the wide third component."

Yo Chris ! Its an eye watering .8" separation , snowman shaped is about it. The more distant companion is often overlooked. Will have another go next week. Was trying 36 Andromedae in the 102, nothing, then defocussed and the diffraction rings split wide open, way to go under,

clear skies ? Nick.

It's just about do-able with my 180 Mak - it's lifted the head off the snowman several times in moments of excellent seeing, so it should be possible with your larger calibre artillery I would have thought?

Chris

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