The Dog Stars – A tale of Two Pups

[Mr Spock]

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.
 

[Captain Scarlet]

I wasn’t aware of Procyon’s pup. Thanks, another one for the bucket-list!

Magnus

[lunator]

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

[John]

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

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 

[Captain Scarlet]

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 😄

[RobertI]

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 

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? 

[Sunshine]

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 November 18, 2021 by Sunshine

[Stu]

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.

[Voyager 3]

For Procyon - I've read no one alive has observed the companion! I'm not surprised are you ? 

 

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

[Mr Spock]

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).

[Mr Spock]

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 

[Stu]

3 hours ago, Voyager 3 said:

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

I did indeed. Let’s make sure we keep it up 👍👍

[IB20]

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. 

[JeremyS]

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.

[Mr Spock]

I briefly got the pup tonight with the 102mm in a fleeting moment of steady seeing. A rarity.

[IB20]

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… 😅

[Mr Spock]

I believe John also got the pup last night. 

[John]

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:

 

 

[IB20]

Fantastic video of Sirius and companion here.

[IB20]

Tonight I’ve exclusively observed Sirius with the FC-76Q around about 9:50pm at 20° altitude. Eyepieces used were the Tak TOEs 4mm and 2.5mm which gave mags of 240x-380x.

Consistently I kept detecting some artefact around 2 o’clock that very, very occasionally appeared like a very small dim companion in between the 2nd and 3rd diffraction rings, sketch attached.

Could this be the pup or is it just scintillation artefact? I have to say tonight is the best I’ve seen Sirius through the 76Q, the diffraction rings were beautifully controlled but it is still a very difficult target especially skirting the rooftops and drifting through heat plumes.

[RobertI]

7 hours ago, IB20 said:

Tonight I’ve exclusively observed Sirius with the FC-76Q around about 9:50pm at 20° altitude. Eyepieces used were the Tak TOEs 4mm and 2.5mm which gave mags of 240x-380x.

Consistently I kept detecting some artefact around 2 o’clock that very, very occasionally appeared like a very small dim companion in between the 2nd and 3rd diffraction rings, sketch attached.

Could this be the pup or is it just scintillation artefact? I have to say tonight is the best I’ve seen Sirius through the 76Q, the diffraction rings were beautifully controlled but it is still a very difficult target especially skirting the rooftops and drifting through heat plumes.

I could be wrong, but I think Sirius B is positioned on the East side, following the direction of drift? 

[IB20]

2 hours ago, RobertI said:

I could be wrong, but I think Sirius B is positioned on the East side, following the direction of drift? 

The sketch is how I saw it through the scope, so needs inverting. I’ve also just realised that East is to my left not my right as my garden view is due South,  so East would be to the right in an inverted image. 🤦🏼‍♂️

Corrected for prism sketch attached.

Edited February 6, 2023 by IB20

[josefk]

You may be on to a winner there @IB20 - https://www.stelledoppie.it/index2.php?iddoppia=27936

[Stu]

Everything in me screams artefact of some sort, BUT, it appears to be in exactly the right place. What eyepiece/fov does the sketch represent?

[IB20]

2 hours ago, Stu said:

Everything in me screams artefact of some sort, BUT, it appears to be in exactly the right place. What eyepiece/fov does the sketch represent?

No idea, it was the 4mm TOE in the 76Q so whatever FOV that gives. The magnification works out at around 238x.

A FOV calculator has it at 0.22°.

Edited February 6, 2023 by IB20