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A question about chasing the Pup star

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#1 MG1962

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Posted 13 January 2013 - 10:45 AM

I have an 8 inch SCT (Nexstar) and am wondering what sort of magnification is needed at the moment to catch Sirius B under pretty average skies. If my research is correct it looks almost identical to Rigel, except the primary is obviously brighter, so if I use the same amount of magnification should I then be able to see the Pup, or is there another element to the equation because Sirius is so much brighter.

I also bought a neutral density filter which I tested briefly on Rigel and was still able to see the secondary star. But conditions were just awful, Sirius looked like a beach ball even at my lowest magnification

#2 azure1961p

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Posted 13 January 2013 - 12:54 PM

I never get a view of Sirius worth crowing about. It's always a fairly ow object in the northeast with an aggravating jetstream
Mucking up the seeing. Still I kno one guy did it in a 100mm refractor and another in an 80mm both with good seeing. And that's the catch - the seeing has to be good for wherever this star is in your sky not merely for what's happening to be the stare of affairs at the zenith.

Pete

#3 Bonco

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Posted 13 January 2013 - 04:38 PM

When Sirius looks like a beach ball its just not a good night to try it. Also if Sirius when viewed without optics is flashing and changing, not good for the pup. Rigel is not a good comparison. It's 99.9% easily viewable in my 60mm refractors. If you get a decent night I suggest using a range of magnification between about 100X and 250X. Good luck, your 8 inch likely has the ability to view it in the right conditions. Bill

#4 rookie

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Posted 13 January 2013 - 11:19 PM

I live at +27.5 lat and have never seen Sirius B with my 8"SCT. I've tried and tried under different times and viewing conditions. Some suggested using a mask to reduce the glare, but I never did make one. I've been more successful with my TV85 using 120x and observing through high cirrus clouds, or during evening or morning twilight. It has been helpful to be familiar with Rigel A&B separation due to the similarity. (differing opinions there! :cool:)

I did have one experience seeing the pup when it was so cloudy that Orion was not visible with eyes only, and Sirius was just seen. I actually saw B quite well through the cloud filter for about 10 minutes, then I lost it. When I looked up from the eyepiece, it had completely clouded over and the sky was opaque. It's a unique experience to see a target better because of the clouds. Recently I've tried to observe the pup during clear nighttime skies using the TV85 with skyglow, neutral density, and polarizing moon filters but so far am unsuccessful.

If you are able to see the pup with your 8"SCT please post your experience. It would be a very good observation.

#5 aa6ww

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Posted 15 January 2013 - 04:30 AM

I have an 8 inch SCT (Nexstar) and am wondering what sort of magnification is needed at the moment to catch Sirius B under pretty average skies. If my research is correct it looks almost identical to Rigel, except the primary is obviously brighter, so if I use the same amount of magnification should I then be able to see the Pup, or is there another element to the equation because Sirius is so much brighter.

I also bought a neutral density filter which I tested briefly on Rigel and was still able to see the secondary star. But conditions were just awful, Sirius looked like a beach ball even at my lowest magnification


You need exceptional seeing conditions to see the pup. This is because you need Sirius to be as less bloated as possible because the pup is in the glare of Sirius and Sirius pulses violently, so you have to wait for the intensity of Sirius's pulsing to subside to see the pup. This is why SCT's have difficulty seeing the pup. Mediocre skies wont reveal it because Sirius will be too bloated. This is also why an APO or long FL refractor can catch the pup, because of the sharper focus which comes from these types of scopes. I can routinely see the pup with my TOA-130, but have never been able to see it in an 8" SCT, though honestly I've never spent much time looking at it with an SCT.
It requires patients to see the pup so dont give up so easy. Get up to 200x and just start staring into the eyepiece with as sharp a focus as you can get. Once you see it, it becomes easier to recognize.

Good luck!!

...Ralph

#6 MG1962

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Posted 15 January 2013 - 12:12 PM

Thanks everyone - It might be a tough project because although I get good transparency, seeing is rarely steady. It sounds like I will need a lot of time at the eyepiece to catch the pup. I also like the idea of haze being used as a natural filter. Lord knows there is plenty of that about






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