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The Dog Stars – A tale of Two Pups


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Sirius

Sirius is one of those stars which creates plenty of debate and questions – and posts here at SGL. Have you seen the pup? Can you see the pup? What size scope do you need to see it?

The problem is, Sirius A is so bright, it overwhelms its companion. This is especially true in the UK due to its low altitude here. Never rising very high, for many, atmospheric disturbances turn viewing Sirius A into a kaleidoscope experience. The pup is buried deep in there somewhere. It’s a challenge, but a rewarding one once you get that first glimpse. With a current separation of 10.9” is about as wide as it gets but will start closing again in a couple of years down to its minimum of 3”. In 2023 it will be 11.33” so you have time to give it a go.

Sirius, or α Canis Majoris, is the brightest star in the constellation of Canis Major – the large dog. Hence it being named the dog star and consequently its companion being called the pup. It’s also the brightest star in the night sky with a visual magnitude of -1.46, and at only 8.6 light years away, is one of our nearer neighbours.

It was Friedrich Wilhelm Bessel in 1844 who noticed changes in the proper motion of Sirius which suggested it had an unseen companion. This was confirmed visually in 1862 by Alvin Clark using an 18.5” refractor.
You don’t need a scope that large however, and a modest instrument could pick it up on a good day.

Procyon

Ah, the other dog star – a little dog this time - α Canis Minoris in the constellation Canis Minor. It’s one of those doubles which passes unnoticed. Although its pup has a similar magnitude difference to Sirius, it’s a lot closer – only 3.8”. That makes it a challenge even for larger scopes.

First seen in 1896 by John Martin Schaeberle using the 36” refractor at Lick, its existence, as with Sirius, was postulated by Bessel. 

Though not as bright as Sirius, Procyon at magnitude 0.34 is still quite prominent. It is also a near neighbour at just 11.46 light years distant.

So, if you see Sirius out tonight, give it a go – you might get a nice pup surprise. If you go hunting Procyon’s pup, then good luck – you’ll need it! It may give you kittens rather than pups.
 

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1 hour ago, lunator said:

Magnus

To give you an idea how difficult Procyon B is have a quick read of this thread

https://stargazerslounge.com/topic/374993-one-step-beyond-sirius-procyon/#comment-4065839

Cheers

Ian

Just to bring that up to date - still no split of Procyon by me whatever I've pointed at it :rolleyes2:

Anyone else managed it ?

I'm looking forward to Sirius A & B again though. As Mr Spock says, the coming few months are a great time to tackle this challenge  :icon_biggrin:

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1 hour ago, lunator said:

Magnus

To give you an idea how difficult Procyon B is have a quick read of this thread

https://stargazerslounge.com/topic/374993-one-step-beyond-sirius-procyon/#comment-4065839

Cheers

Ian

Haha yes I’d guessed that, which is why I mentioned bucket rather than observing 😄

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31 minutes ago, John said:

I'm looking forward to Sirius A & B again though. As Mr Spock says, the coming few months are a great time to tackle this challenge  :icon_biggrin:

Yes I’m going to have another go at the Pup this winter. Not sure which scope I’ll have most luck with - the 102ED (without BVs?), the 150PL or the C8? 

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Great info! I will have a go at Sirius but, from what you say I feel my chances are slim with a wee frac 😂 but there is nothing like a good challenge. I'll point my scope at impossible targets for its aperture and try anyway,  just to say I did, lol.

Edited by Sunshine
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Thanks @Mr Spock, an interesting read!

I shall try for the Pup with the 130mm triplet and also my 8” f8 which really should do it. I hope that my seeing conditions are better down here in Somserset so fingers crossed I get it finally! Hoping E &F in the Trap will be easier too.

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I'll be trying both. Sirius with the 102mm and 250mm and Procyon with the 250mm. As with everyone else, I don't expect to split Procyon; even Sirius is a challenge for me with the poor seeing conditions I get (too many leaky houses).

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3 hours ago, Voyager 3 said:

PS : Stu did you notice how active this forum is after relocation ..?

I've noticed. It was rather tucked away before. Even the post linked to above is in the general observing discussion forum.

For my part I'll be doing these little write ups from time to time. We have a lot of new members at SGL; many are new to astronomy and know little about doubles or even stars themselves. If I can pique their interest in doubles that has to be a good thing :smile:

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  • 1 month later...

Is there an accurate resource for showing where Sirius B should actually be in relation to Sirius currently? I had a look tonight through the 76DC and although it was fairly tumultuous I occasionally spotted something that could have been a dim companion at both 3 o’clockish and also 8 o’clock. 

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33 minutes ago, IB20 said:

Is there an accurate resource for showing where Sirius B should actually be in relation to Sirius currently? I had a look tonight through the 76DC and although it was fairly tumultuous I occasionally spotted something that could have been a dim companion at both 3 o’clockish and also 8 o’clock. 

I’m afraid you’ll need a bigger scope. Have a go at Rigel, though.

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9 hours ago, JeremyS said:

I’m afraid you’ll need a bigger scope. Have a go at Rigel, though.

Rigel is one of my favourites. It was doddle in the 3” Tak with the 7XW last night. Thought there might be a chance with the high-end optics and the current separation of Sirius A/B for the 76DC.

I’ve tried Sirius with my 8” dob and it’s a absolute dog’s dinner. Maybe I need a 4” APO… 😅

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With a refractor the Pup star is to the East of Sirius A so that it trails in an undriven field of view. This was the view with my 120mm refractor when I spotted it last year:

 

sirius270221.jpg.c791f131b175f6a2b0ffda62a9066e5a.jpg

 

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