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Time to get serious about Sirius


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'Tis the season that Sirius is getting reasonably well positioned (well, as good as it gets here in the UK) and it is a good time to take on the challenge of splitting it and seeing the elusive "Pup" star, Sirius B.

This season I'd like to crack this with my ED120 and Tak FC100 refractors having previously achieved it reasonably often with my 12 inch dobsonian and a few times with my 130mm triplet refractor.

For those observing further south, I guess you wonder what all the fuss is about but here, at latitude 51.4 degrees north, this brightest of stars (Sol excepted) is never that far above the horizon so catching a glimpse of the Pup, 10,000 times dimmer than Sirius itself and currently 11 arc seconds from it's much brighter neighbour, can be a real challenge :rolleyes2:

The separation between the stars is currently approaching as wide as it gets though and after all, it's only 8.6 light years away ....... :grin:

I find as steady seeing as possible and somewhere between 200x and 300x magnification is the way to go for this. For me the pair have never looked like a "text book" binary. Sirius shows flaring because it is so bright and the Pup star is seen as a faint point of light glimmering through the fringes of the glare from the massively brighter primary star. When the seeing is steady that is. When it's not, Sirius just seems to spray stray light all around and the shy Pup is nowhere to be seen.

Dry runs on Rigel in Orion are a good way to test the seeing conditions. The the separation between Rigel and it's dimmer companion is approximately the same so you get an idea how far apart Sirius A and B will be. The position angle and the challenge of Rigel are both quite different though but at least you get some idea of whether it's worth going after a split of the "Dog Star".

It really is a fine winter challenge, if frustrating at times, and a good test of the seeing, the optical equipment and the observer :icon_biggrin:

And even if you don't get Sirius, be sure not to miss the splendid nearby triple star of Beta Monocerotis. An easy win stunner in practically any scope :thumbright:

Sirius A & B relative positioning:

Sirius - Alpha Canis Majoris - α CMa | freestarcharts.com

Sirius B is a White Dwarf star and is actually a little smaller than the Earth:

https://nineplanets.org/wp-content/uploads/2019/12/Sirius_B-Earth_comparison.png

Image by Giuseppe Donatiello :

https://live.staticflickr.com/65535/49105223571_94df049f5d_z.jpg

 

 

 

 

 

Edited by John
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'Tis the season that Sirius is getting reasonably well positioned (well, as good as it gets here in the UK) and it is a good time to take on the challenge of splitting it and seeing the elusive "Pup"

Got the little blighter ! First time I've managed it with the ED120. Quite hard and I repeated the observation about 10 times with 2 different eyepieces to make sure. The "Pup" star was not consi

I'm very happy to say that last night (27 Feb) I finally managed to see the Pup! I'm so thrilled by it 🙂  I spent nearly 2 hours observing from 7:30 to 9:30pm and managed to see it both with or w

Posted Images

John, better off than you for latitude by close on 10 degrees and I have done this many a time with the 115mm triplet and the 190mm M/N as well as my Dob, but if you can't see it with a quality 18 inch mirror then the conditions are dire, it has happened.

You may well remember some time back I played a game trying to see it from about you maximum latitude by estimating when it is the same amount of degrees above the horizon, result here are far for wonderful and compare much the same as your own, I don't recall seeing it below 20 degrees with the 115mm but have done with the 180mm Mak and 190mm M/N. I found a power around x150 best for me but there are so many differences between our two sites.

Best wishes for the New Year, lets hope it's a tad better than this one, Alan

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9 hours ago, John said:

I find as steady seeing as possible and somewhere between 200x and 300x magnification is the way to go for this.

Wish i’d gone out last night as the conditions were perfect if a little chilly! The other essential condition I found with my dob is absolute dead calm- the slightest breeze is enough to wobble the pup into oblivion it’s so faint. Good luck with the hunt!

Mark

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Beta Mon was my first triple star and it literally made me make an audible noise at the scope, it remains a favorite to this day.

Ive never had a go at the Pup but your post has encouraged me to have a go, I can’t believe it’s the same size as Earth, amazing!

 I suspect the answer to this is no, but is there a filter that could assist with screening the light from Sirius A?

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I had a naked eye look at Sirius this morning 2-3am i think? 😁 Between patches of cloud. I would like to try and split this double for the 1st time with the 300p this winter. It's still in quite a difficult position to observe for me, at this time of morning it is still coming round the front of my house.

Orion only starts to pass around to the back of my house around 10-11pm at the moment also, I haven't had an opportunity to take in all the double stars yet 😢

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Nice post @John 👍👍

This is one I’ve yet to crack, although I confess I don’t try it that often. It needs to be positioned just right between the houses so the central heating vents don’t trash the seeing. Think I’ll try with my 8” f8 on the EQ platform, that’s probably my best chance. The nag zoom will give x266 to x533 which might do the trick, or the Leica with x2 barlow for x180 to x360 might be better, we’ll see.

EDiT just thinking that now is probably my best chance because there are so few planes flying at the moment so the seeing is better.

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Timely reminder, John. Good luck with the fracs!

Clear here last night but Sirius was scintillating like nobody’s business.
 

Also, good also to see punning post titles being squeezed in before year end, 😂

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I've never split this, it mostly looks like a disco ball from my house with all the turbulence from local rooftops and roads making low altitude observing doubly difficult. If I could make a short trip to somewhere looking across some countryside to get still enough air I might stand a chance.

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2 hours ago, Jiggy 67 said:

 I suspect the answer to this is no, but is there a filter that could assist with screening the light from Sirius A?

I have tried various filters to reduce the glare from Sirius A and they do help with that. Unfortunately they also seem to dim the B star down to the point where it is not visible as well. Or at least I have not seen the Pup when I've been trying with a filter.

I've also tried fitting an occulting bar to an ortho eyepiece, a method which I read about. I used a short section of a steel pin held across the across the field stop of the eyepiece with blu-tak. I could see that this method might work if you have a well aligned driven mount so you can position Sirius A behind the bar and have it stay there while you examine the area immediately adjacent to the star.  My problem was that I use undriven, alt-az mounts so trying to keep Sirius behind the bar while manually tracking at 250x or so AND carefully observing needed the patience of a saint and the dexterity of, er, a very dexterous person. I'm neither :rolleyes2:

It's worth trying these and other methods though. Fun as well :icon_biggrin:

Edited by John
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Thanks John, that’s really useful, I suspected the answer re a filter. The occulting bar seems a good idea, you reminded me that I have also read that in the past as well. I might look at that as a last resort, I should find it easier with a tracking mount and the precise movement a Synscan controller allows though it could be a challenge for that even, probably end up over shooting it back and too for half an hour 😫

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Great thread John, thanks!

Reading it took me back some 4 years to when I first glimpsed the Pup and wrote about it here..

That Vixen 103s was the only scope I am absolutely sure I saw the Pup in to date..I have suspected it in others but never to the point of being sure or even fairly sure, and that includes in my FS128, Andromeda the 5" F15 of known excellence, and another also excellent ED103s, (both latter scopes now in the care of Steve (Saganite).

I think it all comes down to seeing..we have not had great seeing here for a long time..this evening looks as if it could be clear, although it's bitterly cold - minus 3 or 4 last night and our fishpond has had half an inch of ice across it, with no sign of it melting at all, quite the reverse.

The air does seem pretty steady today, quite misty, with no wind at all. I'll just have to see if I can get out after wishing my wife a Happy New Year and bear the cold long enough to get a proper look.

Wish me luck, and a very Happy New Year to everyone..let's hope 2021 brings better times for us all..🙂

Dave

Edited by F15Rules
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15 hours ago, John said:

It really is a fine winter challenge, if frustrating at times, and a good test of the seeing, the optical equipment and the observer :icon_biggrin:

And even if you don't get Sirius, be sure not to miss the splendid nearby triple star of Beta Monocerotis. An easy win stunner in practically any scope :thumbright:

 

 

 

 

 

 

 

 

 

I like to think the optical equipment is ok, if a little short in the aperture department ; its the seeing and the observer thats the problem. And his 53 yr old eyes. And like my age, living at 53ºN in light pollution central.

I spent a good few sessions last winter hunting it down, but no joy i'm afraid. Not even in the ballpark. But i will persevere. You never know......

I can add phantom moons of ice giant planets to that list as well. 

Thanks for the Beta Monocerotis tip. I will check it out 🙂

 

 

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Thanks for the information John, you’ve inspired me to give the pup a proper go. There is a housing estate to my south so not ideal, so I might need to go to a nearby park with decent horizons - this would mean taking the 102ED which I hope might stand a chance under good conditions. 🤞

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8 hours ago, RobertI said:

Thanks for the information John, you’ve inspired me to give the pup a proper go. There is a housing estate to my south so not ideal, so I might need to go to a nearby park with decent horizons - this would mean taking the 102ED which I hope might stand a chance under good conditions. 🤞

You have resurrected a thread from last year .. ! 

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The Pup is certainly an elusive little canine; on occasions recently, it's been relatively easy to spot with my 102mm f13 frac (Vixen objective) but more difficult with my 180 Mak, whereas on other occasions the Mak shows it more clearly than the frac. The flaring around Sirius is usually less with the frac, and this may be a key factor I imagine.

Chris

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The larger the aperture, the bigger the 'flare' I suppose. I know I saw it quite comfortably in the 140mm Mak; never saw it at all with the C9.25. Sirius was just a kaleidoscope in the C9.25... 

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Posted (edited)

Over the past few years I've found my 12 inch dobsonian has been my most consistent performer in showing me the Pup star. I have seen it a couple of times with my 130mm refractor but, as yet, not with my 120mm, 102mm or 100mm fracs.

The dob does produce more diffraction than the refractors of course but I guess the aperture advantage overcomes this and allows the faint star to peek out from the glare.

It is a challenging target even with the 12 inch scope though, unless the seeing is particularly good.

Here is a rough sketch I did of the pair as seen with the 12 inch dob in February 2019 at 265x magnification. Newtonian view so S at the top and W to the left. With an un-driven scope the "Pup" star follows Sirius A as it drifts across the field of view:

siriusfeb2019.jpg.0178173a9c564bc0e55fdaf31aa0e73a.jpg

 

Edited by John
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52 minutes ago, Mr Spock said:

The larger the aperture, the bigger the 'flare' I suppose. I know I saw it quite comfortably in the 140mm Mak; never saw it at all with the C9.25. Sirius was just a kaleidoscope in the C9.25... 

I put it down to be most likely due to tube current effects: if the rate of temperature change (dT/dt) is too high for the insulation around the mak to cope with, there are some tube currents visible, whereas the frac is much less affected by ambient temperature change. But of course, you're right - the brighter the view as the aperture increases, the more you will see flaring effects.

Chris

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Further to my post above on New Year's eve, I did manage to glimpse the Pup with my FS128 at last..I put the following post over on the Astro Lounge but copy it here just to "close off" my post above 😊..

"I had a nice end to the old year tonight..I managed to spot Sirius B (the Pup) with my Tak FS128 at c 10.35pm.

I used a Carton 10.5mm eyepiece barlowed with a Tal 2x Barlow to give approximately 200x. I also strongly suspected the Pup with a Nagler T2 12mm Barlow'd to 195x with a Baader Hyperion zoom Barlow 2.25x

The companion was at approximately 2 o'clock (refractor view with diagonal so right way up but E and W reversed.

Seeing was not as good as I'd hoped due to increasing wind from the flat calm during the day, but it wasn't too bad and it was a matter of using very fine focus adjustments and waiting for those short (very short) periods of relative steadiness.

Well chuffed with getting it! 👍

Dave"

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12 minutes ago, F15Rules said:

Further to my post above on New Year's eve, I did manage to glimpse the Pup with my FS128 at last..I put the following post over on the Astro Lounge but copy it here just to "close off" my post above 😊..

"I had a nice end to the old year tonight..I managed to spot Sirius B (the Pup) with my Tak FS128 at c 10.35pm.

I used a Carton 10.5mm eyepiece barlowed with a Tal 2x Barlow to give approximately 200x. I also strongly suspected the Pup with a Nagler T2 12mm Barlow'd to 195x with a Baader Hyperion zoom Barlow 2.25x

The companion was at approximately 2 o'clock (refractor view with diagonal so right way up but E and W reversed.

Seeing was not as good as I'd hoped due to increasing wind from the flat calm during the day, but it wasn't too bad and it was a matter of using very fine focus adjustments and waiting for those short (very short) periods of relative steadiness.

Well chuffed with getting it! 👍

Dave"

Great news Dave!  I've tried and failed on a number of occasions with my Tak FC-100DL, I shall persevere but I think my 100mm aperture and latitude is against me 😩

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21 minutes ago, jock1958 said:

Great news Dave!  I've tried and failed on a number of occasions with my Tak FC-100DL, I shall persevere but I think my 100mm aperture and latitude is against me 😩

I'm around the same latitude as you. As I said in the opening post, my challenge this winter is to spot the Pup star with my FC100-DL and my Skywatcher ED120 because I've not managed it with those scopes as yet.

The challenge just now is to see any stars at all - it's been pretty solidly cloudy for the past few nights :rolleyes2:

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1 hour ago, jock1958 said:

Great news Dave!  I've tried and failed on a number of occasions with my Tak FC-100DL, I shall persevere but I think my 100mm aperture and latitude is against me 😩

Thanks Iain😊..

Your Tak should be able to do it, my first ever view of the Pup was with my then Vixen ED103s, and it just happened that one very steady night..

Keep at it, I was looking long and hard for some time before I could be sure of my sighting the other night (and I should say I could only see it with my left eye, not my right, which has deteriorated in recent years).

Dave

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