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Old 29-10-2007, 08:46 AM
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iceman (Mike)
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First Saturn of the 2007/2008 apparition

This was also captured on Sunday morning, when Saturn was at around 30° altitude. It's currently 18" in diameter, and apparent magnitude 0.79.

It's my first Saturn image since it has come back into the morning sky, and it's reminded me immediately how difficult an object Saturn is to capture. It's very, very dim at the moment. At the focal length I was working at (over 10.5m), the blue channel, even at 7.5fps (1/8s exposure) didn't have any pixel intensity over 30 (even at 100% gain).

I tried capturing a luminance channel, which was brighter, but the atmospheric dispertion at that altitude really blurred the image. The red channel was the sharpest, but I couldn't even make a normal RGB composite because the blue channel was so poor.

So, here's the red channel.

Next time, until Saturn is brighter and higher, I'll reduce the focal length and at least capture a smaller, but more colourful image
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  #2  
Old 29-10-2007, 09:25 AM
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Lee
Colour is over-rated

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Still looks good! What's the longest exposure you can do at that FL??
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Old 29-10-2007, 09:50 AM
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iceman (Mike)
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With my inaccurate tracking (and the effect of the seeing), 1/3s exposure is pushing it.

Even then, with seeing fluctuations, the detail would've been blurred into a featureless image.
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Old 29-10-2007, 08:27 PM
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leon
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Gee Mike you cant complain about that one, looks pretty good to me..., but than we know what your standards are when it comes to Planet work

Leon
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  #5  
Old 29-10-2007, 10:08 PM
Alchemy (Clive)
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good start. we look forward to a colour version soon.

Cheers AL
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  #6  
Old 29-10-2007, 11:07 PM
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peter_4059 (Peter)
Big Scopes are Cool

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Mike, what were you using to get 10.5m f/l?

The rings are sure looking much more edge on that what I recall from earlier this year.

Peter
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  #7  
Old 29-10-2007, 11:09 PM
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iceman (Mike)
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Thanks guys - next one will be better, I hope.

Peter, I use a 12" newt with 5x powermate + filterwheel, which acts as an extension, giving me approx 10.5m FL.

In very good seeing I may use an extension tube as well, giving me over 13m focal length.
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  #8  
Old 29-10-2007, 11:11 PM
Dennis
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Nice to see the CD and bands given the technical/environmental challenges you faced Mike. I'd be happy with that one for an opener to the season.

Cheers

Dennis
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