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  #1  
Old 07-02-2012, 01:13 AM
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Sirius B with 4" apo ?

On a Dutch forum www.astroforum.nl some guys claim to see Sirius B with a 4" Apo scope. Even in Holland where Sirius transits no more than 21° degrees high. Now I am in Bali with my 4" apo (Televue Genesis) and tried it. Here in Bali Sirius transits as high as in AU just in the south instead of north. I tried, very good seeing and transparency (but only moonlight) but to no avail.
Did anyone see Sirius B in a 4" (10cm) apo ?
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  #2  
Old 07-02-2012, 01:22 AM
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Wow! ... really?!
I split it for the first time the other night using a 10 inch dob at 170x (7mm ep) and it was so tiny!

I'd be curious as well to know if this can be done thru a 4".
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  #3  
Old 07-02-2012, 01:52 AM
Saturnine (Jeff)
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Sirius B

I've been trying for a few months now to split Sirius with my 127 x 1200 ( f 9.4 ) achro and even on nights of steady seeing I can't say conclusively that I've seen "B" , I know the PA and Separation, in other words, where it should be in relation to "A" using that scope and magnification, but no definite sighting.
Can split Rigel and Adhara no problem, which supposedly is a good test to see if your optics are good enough for Sirius, I'll keep trying.

Jeff
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  #4  
Old 07-02-2012, 03:27 PM
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goober (Doug)
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I tried around a dozen times with my 101mm APO 3 years ago BC (Before Child) with no luck. A couple of times I may have seen it, but in hindsight I probably didn't.

It's widened further since, so perhaps I should try it again.

I've never had a problem with Rigel. Never managed Antares either.
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  #5  
Old 07-02-2012, 09:32 PM
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I have seen it in my 10 inch dobbo , same as Suzy said , and once the weather clears up , up here I will try in my 127 apo .
Its getting further from A all the time now so it will get easier over the next decade or so .
Brian.
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  #6  
Old 15-02-2012, 02:01 PM
Poita (Peter)
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I can, *just* in the 105 lomo but it has to be a blinder of a night. Easy as pie in the 10" ACF though. Had no luck whatsoever with the ED80 or the old crummy 5" achro I have here. So depending on the scope I know it is possible with a 4", but it probably has to be a good one and a very good night.
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  #7  
Old 21-02-2012, 02:57 PM
Scopie (Brad)
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Seeing in Bali

Not sure how Bali is but from Singapore with all the extra water vapour in the air I found the seeing to be nothing like an average night in Oz. Of course you have the massive amount of light pollution to deal with there as well, reflected back to you off the steam in the air. I can imaging when you're pushing the limits of your scope that extra atmosphere might make a difference.
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  #8  
Old 10-03-2012, 09:39 AM
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The Mekon (John Briggs)
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I have been trying to resolve Sirius for the past few weeks. Last night here in Whyalla conditions were excellent. Seeing conditions were steady and transparency in the day was excellent, indicated by clear views across the Spencer Gulf to the Flinders Ranges. The full moon was just rising in the east and Sirius high in the north.
Using my Astro-Tech 106, at 144x I was still unable to make out any companion to Sirius. I had started observing in twilight and continued until full night. Shifting the scope to Adhara showed its companion easily. The 5th and 6th stars were visibile in the trapezium. Eta Orion was well split with dark sky between.
So I am with Skysurfer and his original post, unable to split Sirius. I find it impossible to believe observations reported on North American & European forums claiming detection of Sirius B at around 30 degrees elevation with 80mm scopes, when I seem to be getting nowhere with a bigger scope and better conditions.
For the record this scope shows Sirius with 2 diffraction rings, the second quite faint, Sirius B, by my estimate should be clear of these diffraction rings.
Perhaps my eyesight is losing its edge, I use to be a pretty good observer of doubles 20 years ago.
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Old 10-03-2012, 10:56 AM
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Quote:
Originally Posted by Poita View Post
I can, *just* in the 105 lomo but it has to be a blinder of a night. Easy as pie in the 10" ACF though. Had no luck whatsoever with the ED80 or the old crummy 5" achro I have here. So depending on the scope I know it is possible with a 4", but it probably has to be a good one and a very good night.
hi Peter,

What magnification were you using with the ACF on sirius?

josh
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Old 11-03-2012, 10:38 PM
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I'm with you - I can occassionally pick it in a 25" in good conditions, not been able to in a 10", and not even in my magical Antares-splitting 4" Unitron.
What I can always see in any scope from 3"-25" is a ghost image of Sirius from one of the internal surfaces of the eyepiece, and at these powers I'm usually looking through a TV radian, so it's not like the eyepiece is especially bad. Unless people can confirm the correct separation and position angle of the pup, it's hard to be sure they haven't seen a ghost. Of course, my 41 year old eyes are a lot yellower than they were.
cheers,
Andrew.


Quote:
Originally Posted by The Mekon View Post
I have been trying to resolve Sirius for the past few weeks. Last night here in Whyalla conditions were excellent. Seeing conditions were steady and transparency in the day was excellent, indicated by clear views across the Spencer Gulf to the Flinders Ranges. The full moon was just rising in the east and Sirius high in the north.
Using my Astro-Tech 106, at 144x I was still unable to make out any companion to Sirius. I had started observing in twilight and continued until full night. Shifting the scope to Adhara showed its companion easily. The 5th and 6th stars were visibile in the trapezium. Eta Orion was well split with dark sky between.
So I am with Skysurfer and his original post, unable to split Sirius. I find it impossible to believe observations reported on North American & European forums claiming detection of Sirius B at around 30 degrees elevation with 80mm scopes, when I seem to be getting nowhere with a bigger scope and better conditions.
For the record this scope shows Sirius with 2 diffraction rings, the second quite faint, Sirius B, by my estimate should be clear of these diffraction rings.
Perhaps my eyesight is losing its edge, I use to be a pretty good observer of doubles 20 years ago.
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  #11  
Old 12-03-2012, 09:05 AM
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The Mekon (John Briggs)
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Quote:
What I can always see in any scope from 3"-25" is a ghost image of Sirius from one of the internal surfaces of the eyepiece, and at these powers I'm usually looking through a TV radian, so it's not like the eyepiece is especially bad. Unless people can confirm the correct separation and position angle of the pup, it's hard to be sure they haven't seen a ghost. Of course, my 41 year old eyes are a lot yellower than they were.
cheers,
Andrew.
Thanks Andrew for mentioning this ghost image. I had noticed this as well and it could easily be mistaken for a faint companion, especially on those using goto scope. If the drive is off or you shift the dec axis this ghost can move in the field relative to Sirius, so you clearly know it is not Sirius B. I would say that this ghost image accounts for many reports of detection.

When I get back east to my 130EDT Starfire, given some good conditions I will try again. If this scope cannot pick it up then I will write off all observations in scopes of less than 4". The 130 can pick out Enceladus against the disc of Saturn, so if any smaller scope can detect Sirius B, this one will.
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  #12  
Old 12-03-2012, 09:11 AM
Poita (Peter)
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Quote:
Originally Posted by Joshua Bunn View Post
hi Peter,

What magnification were you using with the ACF on sirius?

josh
Around 300x and using the electronic focuser.
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  #13  
Old 12-03-2012, 11:21 AM
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I saw it with my 12" Newt but did not with my 4" APO. I must try it again.
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  #14  
Old 13-03-2012, 12:51 AM
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Thanks Peter
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  #15  
Old 25-03-2012, 11:46 AM
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The Mekon (John Briggs)
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YES! at last Sirius B detected with my 4" Apo!

A cooler and clearer night saw skies 30km west of Whyalla quite steady.

Started observing Sirius as the sky darkened at sometime between nautical and astronomical twilight, the liitle B popped out just east of Sirius. Not constant at first, but as the sky drew darker, much more consistently, and I was able to say for sure it was there.

In full darkness it was not as easy to see, but I am satisfied now that it can be detected in a 4"scope. Again the "ghost" images that Sirius can invoke may trick many into thinking they have seen this little B. I had the ghost image sitting about 20" north of the the star while I made this observation. You can easily shift this image to get it out of the way, but I found the closer I had Sirius to the centre of field, the closer this image got towards Sirius. It also appeared like an 8th mag star, but much sharper and clearer than the companion.
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Old 25-03-2012, 05:12 PM
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Quote:
Originally Posted by The Mekon View Post
YES! at last Sirius B detected with my 4" Apo!

A cooler and clearer night saw skies 30km west of Whyalla quite steady.

Started observing Sirius as the sky darkened at sometime between nautical and astronomical twilight, the liitle B popped out just east of Sirius. Not constant at first, but as the sky drew darker, much more consistently, and I was able to say for sure it was there.

In full darkness it was not as easy to see, but I am satisfied now that it can be detected in a 4"scope. Again the "ghost" images that Sirius can invoke may trick many into thinking they have seen this little B. I had the ghost image sitting about 20" north of the the star while I made this observation. You can easily shift this image to get it out of the way, but I found the closer I had Sirius to the centre of field, the closer this image got towards Sirius. It also appeared like an 8th mag star, but much sharper and clearer than the companion.
Congrats - good to know it's worth perservering with. I'll have to try again with the 4" f15. What magnification were you using?
regards,
Andrew.
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  #17  
Old 25-03-2012, 05:30 PM
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The Mekon (John Briggs)
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Thanks Andrew.

magnification 144x in this little scope, good luck with your F15, the right night will reward you
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