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Saturn May 30/31

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#1 idp

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Posted 31 May 2013 - 10:05 AM

Good seeing forecast for the New Haven area last night, so I gave a try to Saturn with my 10" f/7 newton. Seeing was about II Ant., and Saturn looked indeed magnificent at 440x. Not bad at all compared to the same-diameter Clark refractor I used 3 nights ago, and one does really appreciates the sharp, chromatism-free image! The most subtle details were definitely easier to see in the Clark though, despite seeing being only average on the 28th.

On the other hand, on my newton I still have to track manually which is PITA. No way I can track, observe and produce an accurate sketch at the eyepiece. The one below is just a (rather poor) color rendering I produced after the observation. I used crayon on regular xerox paper which was not really suitable, then smoothed it out with the blur tool in Gimp.

I spent a couple of hours at the telescope, between ca. 11:00pm and 1:00am (well half of this time was about tracking and re-centering). I tried a W58 green filter which did increase the contrast between the polar cap and the surrounding zone, but not enough to make up for the loss of light. I guess it would have been useful in a larger diameter though.

It was a wonderful vision, hard to leave it and go to bed...

Ivano

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#2 JimPie

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Posted 31 May 2013 - 10:34 AM

Ivano,
Another great rendering of Saturn. Must have been a nice view indeed!

#3 kenrenard

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Posted 31 May 2013 - 12:35 PM

Ivano,
Great work. I would have loved to get that view. Bravo.


Ken

#4 azure1961p

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Posted 31 May 2013 - 02:42 PM

Ivano,

Another great one. If you don't already have it I guarantee you this- a 5" fan behind the primary and a 100mm fan blowing in from the side will give you a definite improvement.

Very nice my friend!

Pete

#5 niteskystargazer

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Posted 31 May 2013 - 02:42 PM

Ivano,

Very good sketch of Saturn :).

CS,KLU,

:thanx:,

Tom

#6 idp

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Posted 31 May 2013 - 07:39 PM

Ivano,

If you don't already have it I guarantee you this- a 5" fan behind the primary and a 100mm fan blowing in from the side will give you a definite improvement.


I guess I may try, I got the fan months ago but have not mounted it yet because... I have not felt the need yet.

The tube is large and there's plenty of room between the mirror and the inner walls, the bottom is open, I keep it in the garage which is not heated and usually I can take it out hours before the time I have planned to observe. I mean, when the seeing should be good, I regularly get it good or excellent it's not like internal currents seem to be a factor.

I imagine the fan would be a must in case of big differences between day and night temperatures, so that the mirror has a hard time "catching up". However, it seems to me that this is rarely the case in Connecticut. Even the 10" Clark at Bethany is generally OK an hour or so after I've opened the roof (but you must remember to open the small vent close to the objective lenses :smirk:).

Not saying a fan is useless in general, maybe I should try it and see what happens.

Ivano

#7 Andrev

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Posted 31 May 2013 - 08:12 PM

Beautiful sketch.

Andre

#8 Aquarellia

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Posted 01 June 2013 - 12:00 AM

Very nice indeed

#9 chrisrnuttall

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Posted 01 June 2013 - 03:29 AM

I can well imagine you trying to track. observe and sketch at 440X, I couldn't do it with my 12" and had to build an EQ platform for it.

I really like the drawing despite you saying it is rather poor, the NEB looks very good, I have yet to notice a redder southern edge to it, but I have seen others draw it as you have.
good work!

#10 idp

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Posted 01 June 2013 - 09:32 AM

I saw the redder southern edge pop up once or twice, but it doesn't really look like in the drawing; I just got it wrong! Same for the color of the south polar region, which was more "yellowish". Your drawing is actually another planet :D

This is why I think it's a rather poor rendering, I just decided to try with colors. I find it difficult in general to render the hues of Saturn, which are rather subtle, with crayons (Mars it easier from this point of view). Maybe pastels would work better? And then, being at the eyepiece would have helped too but finding a 30 RPM AC motor is a quest this days.

Ivano

#11 azure1961p

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Posted 01 June 2013 - 11:59 PM

I think you'd find pastels (dry not oil pastels) actually a nice gentle way to tone the drawing. It can be tricky toning a graphite pencil drawing with Pastel but the hues are soft and gentle enough a little pastel goes a long way.

Something that Dave Gray does and Ive found superior to toning with pastels for my own needs is coloring with a computer program. I set the opacity of the color between 8-12% and I can get these nice transparent tones. For me its the way to go.

I've yet to use pastels on proper paper (velour paper) but even on copier paper its not all bad. Velour paper is the way to go though.


Pete






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