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Rutilus
Pooh-Bah
Reged: 12/17/10
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The Pup- Fantastic seeing
#5603314 - 01/03/13 04:22 PM
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With Sirius only getting to around +19 degrees altitude from my site, it takes a night of really good seeing to go after the Pup. For the past two days it has very mild here at around +12C, and last night with my Carton 100mm f/13 Achromat I was taken by how easy it was to see stars E and F in the Trapezium. Moving down to Rigel, I got a quite wonderful view with the star presenting a very stable image.
So this was definitely the night to go Pup hunting. Using a 12.5mm Baader Genuine Orthoscopic eyepiece (104x) Sirius gave a stunning view, never before had I seen the image so stable. With the Carton lens, Sirius was pure brilliant white, with just the very tiniest flash of blue C.A. visible. I picked the Pup up within about 10 seconds of getting Sirius into the eyepiece, there it was, no if's no but's, not just glimpsed now and again, but a constant steady faint dot.
What a fantastic view, I spent the next hour just taking in the view, this type of seeing so low down is exceedingly rare for me from this location.
I tried several different filters to see which if any gave an advantage.
1. No-Filter. The Pup was seen very well in spite of the brilliance of Sirius. 2. Baader Semi-APO. The only difference I could see over the non-filtered view was a slight dimming of the over-all view. Still the companion star was still easy to see. 3. Baader Contrast Booster. This filter did make a difference, it completely removed the bluish tint of C.A. from the eyepiece view. There was a very slight colour cast, with Sirius now appearing a slightly dirty white. However it provided the best views of the companion. 4. Yellow and Green filters. The companion was still visible when using these filters, a bit harder with the green filter.
So on the night, the Contrast Booster filter work very well indeed, and on nights of average seeing I think this will be the one I use when Pup hunting.
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Kon Dealer
professor emeritus
Reged: 01/05/11
Loc: Cambridge UK
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Re: The Pup- Fantastic seeing
[Re: Rutilus]
#5603429 - 01/03/13 05:55 PM
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Isn't the Baader semi-APO a combination of the Contrast Booster and Fringe Killer? If so I'm puzzled why it didn't perform similarly?
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Rutilus
Pooh-Bah
Reged: 12/17/10
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Re: The Pup- Fantastic seeing
[Re: Kon Dealer]
#5604907 - 01/04/13 02:23 PM
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Kon, interesting what you say regarding the Semi-Apo.
I have now tried this filter on half a dozen achromats,and all it does is dim the image slightly compared to the un-filtered view.
Any C.A. visible remains the same in the all the scopes I tried it on. With the filter there is no colour cast, unlike the Contrast Booster
which gives a slightly pale yellow tint. On all the scopes I tried the Contrast Booster completely removes any trace of C.A.
On my refractors, the Semi-apo has been a complete waste of time. However, when used with my C9.25 SCT it is a superb Mars filter.
Last night I viewed Sirius again but in just average seeing conditions, the Pup was much harder, this time only visible
in moments lasting 3-5 seconds at most.
Edited by Rutilus (01/04/13 02:28 PM)
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