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A decent view of Saturn, with a bonus Neptune.

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#1 chrisrnuttall

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Posted 22 September 2019 - 04:14 AM

Hi everyone.

I haven't posted anything since the end of the Mars apparition due to the low altitude of the gas giants from my location in the North of England; trees in neighbouring gardens give me only a small window of observing time which starts when a planet crosses the meridian, and lasts about 50 minutes from then. This means that I have no flexibility in when I can obverse, and I need those few minutes to correspond with a period of good seeing, without cloud, and to be at a time which is convenient for me to be outside. Many aborted attempts throughout the summer have yielded me a handful of unimpressive Jupiter sketches and just a couple of Saturn.

In an attempt to improve the quality of the view while the planets are seen at such low altitude I have purchased an atmospheric dispersion corrector, and I am very pleased with the results; it is easy to use, and has helped to sharpen up the image quite a bit.

 

So when I was was driving to work on Thursday morning and saw that the sky was deep blue, with no breeze at all at ground level, and that the aeroplane contrails which crossed the sky at high altitude were persisting without being blown away, I knew that the evening had a chance of being a good one, even if Saturn would be transiting just as the sky became dark enough to find it, and then it would be crawling along in the hazy soup low down in the South.

 

After getting home from work I made sure I was outside with the telescope aimed in the right place a few minutes before Saturn emerged from its occultation by the apple tree, and sure enough as soon as it cleared the final leaf the view was pretty steady, if a little soft, but I could straight away trace the Cassini division right around the rings, the NEB stood out rich and dark with a very bright band to its south in the EZ, and a pale band to its north. The polar region presented a dark brown oval and further banding was evident in the temperate regions.

Over the following minutes the only disruptions to my observing came from the occasional ripple sweeping lazily through the image, I even had a few moments of very good seeing where the image stood stationary and sharp and the contrast was improved so that the brighter parts of ring B, and the EZ band, seemed to positively glow white. A memorable view which I can still see if I close my eyes.....

 

Given that Saturn had a peak altitude above the horizon of just 11° the seeing was amazing, I mean not as good as the views several years ago when the planet rode high up in crisp winter skies, and the crepe ring looked like a grooved LP record, but definitely the best view I have had for a good three years.

 

So here it is, my only decent sketch of Saturn so far this year.

 

By the way, I don't know why there is a colour disparity between the two sides of the rings in my drawing, I think it might be to do with the lighting under which I photographed it, I didn't observe this effect on Saturn! 

Attached Thumbnails

  • Saturn 2019 09 19 Posting.jpg

Edited by chrisrnuttall, 22 September 2019 - 07:11 AM.

  • IVM, stanislas-jean, Jef De Wit and 6 others like this

#2 chrisrnuttall

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Posted 22 September 2019 - 04:21 AM

Then the following night I decided to have a peek at Neptune. The day had been breezy and that evening the seeing wasn't as good despite observing at higher altitude above the horizon. Neptune was easily located thanks to its proximity to some bright stars in Aquarius. Its tiny diameter demanded higher magnification than the seeing would allow, and its dimness meant that I couldn't use my apodizing mask effectively.

 

I could discern a darker limb and a brighter centre to the disc, and an obvious blue hue. The top and bottom of the disc did also seem slightly darker, but this could be to do with atmospheric dispersion / the ADC. All very marginal and not to be taken very literally.

Attached Thumbnails

  • Neptune 2019 09 20 Posting.jpg

Edited by chrisrnuttall, 22 September 2019 - 04:31 AM.

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#3 Aquarellia

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Posted 22 September 2019 - 08:10 AM

Whaw, respect for your 2 sketches.

Bravo!

It's nice to see that someone else is looking to the faraway Neptune.

Michel



#4 frank5817

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Posted 22 September 2019 - 12:04 PM

Chris,

 

Both of these are stunning sketches. So sharp and crisp.

Excellent post.

 

Frank :)



#5 IVM

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Posted 22 September 2019 - 01:09 PM

Great work! What sort of apodizing mask is that?



#6 chrisrnuttall

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Posted 22 September 2019 - 02:48 PM

Great work! What sort of apodizing mask is that?

It's a 3 layer aluminium insect screen mask, diameters calculated from Harold Suiter's excel file.

which can be downloaded here

http://www.bay-astro.../TM/apodize.htm

 

It works very well on my 12" newtonian, and I use it 95% of the time on that scope.

I also made one for my 5" Mak, but that does not improve the view in that scope, apparently they really only work for larger apertures with smaller central obstructions.


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#7 azure1961p

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Posted 22 September 2019 - 02:48 PM

Among your best Chris!!

 

Surprised you didn't get the inner edge of the A rings whiteness.

All those shades and hues in the temperate regions, that's what so terrific about your work - the extra effort to bring about the nuances of the view.

 

Accolades here dude.

 

Pete



#8 azure1961p

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Posted 22 September 2019 - 02:55 PM

Then the following night I decided to have a peek at Neptune. The day had been breezy and that evening the seeing wasn't as good despite observing at higher altitude above the horizon. Neptune was easily located thanks to its proximity to some bright stars in Aquarius. Its tiny diameter demanded higher magnification than the seeing would allow, and its dimness meant that I couldn't use my apodizing mask effectively.

 

I could discern a darker limb and a brighter centre to the disc, and an obvious blue hue. The top and bottom of the disc did also seem slightly darker, but this could be to do with atmospheric dispersion / the ADC. All very marginal and not to be taken very literally.

 

I like that you check yourself here with suspecting at least a variable in the seeing that could cause issues.  The falling off if illumination away from center, hence the brighter middle is well shown and explained.

 

Again that Saturn rocks.

 

Pete



#9 niteskystargazer

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Posted 23 September 2019 - 01:33 PM

Chris,

 

Very good sketches of (A decent view of Saturn, with a bonus Neptune) smile.gif .

 

CS,KLU,

 

thanx.gif ,

 

Tom




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