Mizar And Alcor Observation.

[Guest]

This evening, I tried for the M5 Rose Cluster - without luck.  I really need to get this sky navigation thing practised more!  I ended up looking at Izar, but I still cant separate the double.  Knowing my luck, I already have but haven't realised it yet!  I was about to call it a night with the 8" Dob, but thought I'd try The Plough, which practically overhead.  I tried to align the Dob with the finderscope, but nearly poked my eye out - I really need a RACI one. 

I eventually got it on to Mizar using a 25mm MA EP, clearly seeing Mizar and Alcor.  I swapped it for the 10mm MA EP and it was more obvious that I was looking at a double star.  I cheated somewhat and got out the BST StarGuider 8mm ED EP, which probably wasn't required.  It was stunning to look at, as the separation between the two was stunning clear! 

Lastly, I tried the BST StarGuider 3.2mm ED EP.  Believe it or not, it actually worked!  It was obviously dimmer through this EP than the previous ones, but you could still clearly see Mizar and Alcor with very little difficulty!

[Space Hopper]

One of my favourite doubles 😀

When i checked it earlier, it was pretty much bang on the zenith

[Stu]

Mizar and Alcor were the first thing I ever viewed through a telescope, after reading about them in a Patrick Moore book. I still visit and enjoy them regularly. Lovely grouping.

[Waddensky]

Wonderful report, thanks for sharing! Must have been a great night.

Is it safe to assume you observed Mizar A & B? Mizar and Alcor are an easy naked eye pair, Mizar AB requires a telescope at 14" separation. It was the first double star discovered in the 17th century.

[Guest]

3 hours ago, Waddensky said:

Wonderful report, thanks for sharing! Must have been a great night.

Is it safe to assume you observed Mizar A & B? Mizar and Alcor are an easy naked eye pair, Mizar AB requires a telescope at 14" separation. It was the first double star discovered in the 17th century.

I'm fairly certain it was Mizar and Alcor.  The LP levels here a quite high, so seeing them separate is difficult.  I think my eyesight isn't as good as it once was...

Edited May 14, 2020 by Guest

[Waddensky]

33 minutes ago, merlin100 said:

I'm fairly certain it was Mizar and Alcor.  The LP levels here a quite high, so seeing them separate is difficult.  I think my eyesight isn't as good as it once was...

In that case, take a close look at Mizar next time with the eyepieces you mentioned ☺️. There's another nice surprise waiting for you there.

[Stu]

2 hours ago, merlin100 said:

I'm fairly certain it was Mizar and Alcor.  The LP levels here a quite high, so seeing them separate is difficult.  I think my eyesight isn't as good as it once was...

This is a fairly decent picture of the system, Mizar A and B, plus Alcor further away. I’ve just about split Mizar in x15 stabilised binoculars so it isn’t difficult to do in a scope.

[F15Rules]

The Mizar system is superb and one of my long time favourites. It's very easy to split Mizar itself and the faint star you can see in Stu's picture (in between Mizar on the left and Alcor on the right is called Sidus Ludovicanum..you can read more here: (also follow the link to a very nice image of the system, it's safe to view!)..

Dave

 

Edited May 14, 2020 by F15Rules

[Guest]

I think it's now obvious that I've been seeing Mizar A and B! 😟

[Stu]

10 minutes ago, merlin100 said:

I think it's now obvious that I've been seeing Mizar A and B! 😟

A good thing not a bad thing surely?

[Waddensky]

1 hour ago, merlin100 said:

I think it's now obvious that I've been seeing Mizar A and B! 😟

Great, Mizar is a very nice pair! Maybe you can try Algieba (Gamma Leonis) next time, a bit tougher but a lovely golden couple. One of my favourite double stars.

[Guest]

2 hours ago, Stu said:

A good thing not a bad thing surely?

It is, I was looking for the confused emoticon...  I think I may have been looking at Izar and the other star was there all along.  Perhaps I missed just how much separation there actually is.  I understand degrees, but the small subdivisions are something I have to work on.  I get the hours, minutes and seconds, but using the in practise is something else...

[devdusty]

Unfortunately  Alcor is not visible from a light polluted  site. I think people should qualify the comment that it is an easy naked eye double from a dark site.!

Chris

[Stu]

10 minutes ago, devdusty said:

Unfortunately  Alcor is not visible from a light polluted  site. I think people should qualify the comment that it is an easy naked eye double from a dark site.!

Chris

What do you class as light polluted Chris? My skies are mag 5 NELM, Bortle 7 at best and it is easily visible from here. It is magnitude four so should be visible in all but the inner cities I would think?

[John]

The Mizar-Alcor pair are pretty straightforward under any reasonable sky with the naked eye. The separation between them is 12 arc minutes.

To split Mizar into it's 2 components, Mizar A and Mizar B, requires a scope. The separation between these is 14 arc seconds.

 

 

[Waddensky]

9 minutes ago, devdusty said:

Unfortunately  Alcor is not visible from a light polluted  site. I think people should qualify the comment that it is an easy naked eye double from a dark site.!

Chris

Alcor is around magnitude 4.0 and should be visible even from incredibly light-polluted areas. But my comment earlier about the easy naked eye split was based on separation, not brightness.

[Captain Scarlet]

I am currently at a lovely dark bortle 3 site, 21.8 on a decent night, but mainly live SW of London Where it’s bortle 7 19.1 not far from @Stu. Naked eye, I find exactly the same ease/difficulty to discern Alcor at both places! I think what makes it more difficult naked eye is its proximity to much brighter Mizar.

i should add, I can make out Alcor from both places...

Edited May 15, 2020 by Captain Magenta

[devdusty]

Hello Stu. My sky is bortle 8  and I struggle to see stars dimmer than mag. 3.5 with the naked eye.  For instance Megrez  mag.3.3  in Ursa Major is virtually overhead at present  but is very faint.

Chris

[Waddensky]

18 hours ago, devdusty said:

Hello Stu. My sky is bortle 8  and I struggle to see stars dimmer than mag. 3.5 with the naked eye.  For instance Megrez  mag.3.3  in Ursa Major is virtually overhead at present  but is very faint.

That's part of the difficulty with naked eye limiting magnitudes, there are so many factors involved: transparency, nearby light sources, visual aquity, etc. In general, the NELM for a Bortle 8 site is considered to be around mag 4.5 (source), but this of course differs from person to person and from location to location.

[Guest]

For the first time in nearly a week, I could see the Plough again.  Using my friend's 4.5" reflector and a magnification of 36x (25mm MA EP), I could clearly see Mizar A and B with Alcor off to the right hand side, I can also see Sidus Ludoviciana between them.  At magnification 90x (10mm MA EP), Mizar A and B become even more prominent, Airy disks.

[Stu]

On 20/05/2020 at 23:35, merlin100 said:

For the first time in nearly a week, I could see the Plough again.  Using my friend's 4.5" reflector and a magnification of 36x (25mm MA EP), I could clearly see Mizar A and B with Alcor off to the right hand side, I can also see Sidus Ludoviciana between them.  At magnification 90x (10mm MA EP), Mizar A and B become even more prominent, Airy disks.

Excellent! They make a beautiful grouping and as said, one I’m still not bored with 20 years or more after I first viewed it.

The amazing thing is that Mizar A and B, as well as Alcor are spectroscopic Doubles too (ie too close to split in a scope but detectable by spectroscopy), so there are actually six stars in the system you are looking at! They are all gravititationally linked too so are a genuine system, not just line of sight.

https://en.m.wikipedia.org/wiki/Mizar_and_Alcor

https://earthsky.org/brightest-stars/mizar-and-alcor-the-horse-and-rider

[Barry-W-Fenner]

17 minutes ago, Stu said:

Excellent! They make a beautiful grouping and as said, one I’m still not bored with 20 years or more after I first viewed it.

The amazing thing is that Mizar A and B, as well as Alcor are spectroscopic Doubles too (ie too close to split in a scope but detectable by spectroscopy), so there are actually six stars in the system you are looking at! They are all gravititationally linked too so are a genuine system, not just line of sight.

https://en.m.wikipedia.org/wiki/Mizar_and_Alcor

https://earthsky.org/brightest-stars/mizar-and-alcor-the-horse-and-rider

Very interesting to hear that Stu. I thought they were just a pair! A fine pair of stars mind. They bring fond memories as they were the 1st double I observed last September. Its great to see them coming back, I will check them out in more detail this time around 👍

[Waddensky]

40 minutes ago, Stu said:

The amazing thing is that Mizar A and B, as well as Alcor are spectroscopic Doubles too (ie too close to split in a scope but detectable by spectroscopy), so there are actually six stars in the system you are looking at! They are all gravititationally linked too so are a genuine system, not just line of sight.

Another amazing fact is that this 6-star system is actually part of the Ursa Major Moving group or Collinder 285, a stellar association thought to have a common origin and similar age. Most other stars of the Big Dipper are also part of this group, as well als 'stream stars' like Alphecca (CrB) and Menkalinan (Aur). They are not gravitationally bound anymore, but share their motion in space and chemical composition.

Edited May 24, 2020 by Waddensky

[Second Time Around]

48 minutes ago, Waddensky said:

Another amazing fact is that this 6-star system is actually part of the Ursa Major Moving group or Collinder 285, a stellar association thought to have a common origin and similar age. Most other stars of the Big Dipper are also part of this group, as well als 'stream stars' like Alphecca (CrB) and Menkalinan (Aur). They are not gravitationally bound anymore, but share their motion in space and chemical composition.

Something else I didn't know.  Thanks.