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MarsG76

Zenith Saturn, Jupiter & Moon Observation 11 July 2017

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Observation 11 July 2017

Date: 11th July 2017 @ 20:50 – 22:30AEST

Location: Backyard

Equipment: 14” Skywatcher GOTO Dobsonian, Televue 31mm Nagler T5 , Televue 17mm Ethos, Televue 11mm Nagler T6, Celestron 5mm, LV 7mm, Televue 2X Powermate, Baader Neodymium, Baader Contrast Booster, Circular polarizer.

 

Tonight is looking like it is a good night to do some observing and try out the new shroud for the Dobsonian.

The Seeing was quite stable, there were clouds flowing south to north direction but not so many as to ruin any observing.

The moon is just the second day past full moon phase and so still lights up the night sky, Saturn and Jupiter are in the sky along with the moon so knowing that I will not be looking at any DSO I decided to have a look at these three objects.

 

Jupiter: Jupiter was the first object on the agenda to view since it is already getting low in the western horizon, still 40 or so degrees but knowing that the best views are when the planets are highest in the sky, I didn’t want to leave it any later.

The view was a little hazy, the highest magnification where Jupiter looked OK was at max about 150X-235X. The GRS was visible just past the center of the SEB. To see it quite clearly I still had to wait for the fleeting moments of clarity, but it was constantly visible.

I didn’t see any fine intricate details with in cloud bands as in the past, and honestly even the polar cap shading was a challenge. Definitely no shadows from any moons on the Globe.

There were all 4 Galilean moons visible.

It was nice to revisit Jupiter as it is moving further away from us, even if the view was not even close to the best views I have experienced while observing Jupiter in the past.

 

Saturn: Saturn was the next in the cue, as it was right above head, near zenith, I was expecting to see Saturn more clearly than Jupiter. Initially Saturn was more stable, and the Cassini division was visible on the edges but not the best I have seen to date, even with the 8” SCT.

As I was adjusting focus on Saturn, when defocussing it a bit further out, I noticed that Saturn was defocussing asymmetrically, only slightly but asymmetrically so I knew that my collimation must be slightly out. I adjusted the collimation using a glass combination to give me 660X magnification until Saturn was defocussing symmetrically. At 660X Saturn was better than before collimation but still soft, so I dropped the magnification to 300X and the view was crisp and detailed, collimation was a major improvement.

I stacked the Neodymium and contrast booster filters on to the eyepiece and the view was breath taking.   

During the moments of best stability and clarity, the Cassini division in the rings was visible nearly all the way around, became hard to see behind and in front of the planet. The rings in front of the globe were easily visible/distinguishable, along with the darkening on the globe, shadow cast by the rings on to the atmosphere. The rings were visible poking above the globe from behind, this is a good time to see Saturn with it’s rings fully open facing toward us.

The globe showed darker but still quite pale cloud bands, one just above the ring and the second more subtle shading about ¾ of the way toward the pole.

There were 5 moons visible, Titan, just barely visible Enceladus, faint Dione and Thehys and Rhea.

The best view of Saturn was at 300X-300X (11mm Nagler with 2X PM and 5mm Celestron X-Cel) magnification, the scale of Saturn was quite big with clear detail easily visible. Magnifying 470X was ok but obviously softer. Sure the planet was visibly bigger but I still preferred the view at 300X.

 

Moon: The moon, being just past full moon, only showed craters at one of the edges, but using the 31mm Nagler T5 or the 17mm Ethos, with the polarizer still looked amazing. The full face of the moon was visible at one time, the 17mm Ethos magnifying it so much and with the 100 degrees AFOV, I had to look around to see the edge of the moon… it was like looking out of a space craft window, it was awesome.

The 31mm Nagler showed the whole face magnified a bit less and while using both of the eyepieces, having the Polarizer turned down to the dimmest level revealed the moon ejecta streams, flat craters and Maria on the surface as well as bright spots dotted throughout the landscape, looking almost looking like city lights.

The Polarizer has to be turned all the way to the darkest level with the 14” mirror since without it is so bright that looking at it is actually quite uncomfortable. Even with the Polarizer, I think I could have added a ND filter to bring the intensity a little bit more.

Sure the most contrasty views where you can see a lot of detail in the craters is during a phase, but looking at the full, or near full, moon looks beautiful when adding the extra constant using darkening filters, bringing out the dark shading.

 

 

Overall the night of viewing was very rewarding, especially with the great views of Saturn.

The shroud seems to have done the trick at keeping the light path clear of any stray light, but the best part I found was that with the 3 fans blowing from behind the primary mirror, there was a slight, very slight air flow out of the front of the Dobsonian.

 

I’m hoping that this air flow will keep any dew from settling onto the primary or more importantly the secondary. A couple of months ago I took the 14” SW to one of my favourite dark sites in the mountains, but my observing night was cut very shot, very quickly due to dew fogging out my secondary, even when cleaning it with lens cleaner, the dew was already building up as soon as I took my hand away.

 

I have some dichrome that I’m planning to add to the secondary as a spiral on the back to create a dew heating system, but whether I’ll do that will depend on if the secondary will get covered in dew in a future observing trip with the shroud on while the back fans are moving air out.

 

Another things I have noticed tonight is that the order in which the Neodymium and Contrast booster filters are stacked makes a difference to how the view looked. Initially while observing Saturn, when I added the two filter, the view was not any more stable than when not using any filters, only slightly dimmer. But when reversing the order of the filters, the view stabilised noticeably, literally the difference was between OK and WOW.

I would think that each filter cuts out a certain wavelength of light and passes on the rest, and so it shouldn’t matter what order they are stacked.

I repeated the experiment but flipping the filters and same result, one way was not better than with no filters, but the other way it was stable and razor sharp???!!!!

 

Does anyone have an explanation to this phenomenon?

 

Thanks for reading, Clear Skies.

Edited by MarsG76
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1 hour ago, MarsG76 said:

I stacked the Neodymium and contrast booster filters on to the eyepiece and the view was breath taking

I have both of these filters but have never tried stacking them. Which way round was the most successful for you?

Great detailed report :D

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25 minutes ago, Littleguy80 said:

I have both of these filters but have never tried stacking them. Which way round was the most successful for you?

Great detailed report :D

You're in for a treat... Contrast booster first on to the EP and the Neodymium on the end... 

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Great report MarsG, I enjoyed reading that one!

Interesting how different things work for different people/circumstances. I have found the Neodymium filter to be very useful on Mars and Jupiter but not on Saturn. Glad it worked for you!

Saturn nearly overhead must be fabulous!

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16 hours ago, Stu said:

Great report MarsG, I enjoyed reading that one!

Interesting how different things work for different people/circumstances. I have found the Neodymium filter to be very useful on Mars and Jupiter but not on Saturn. Glad it worked for you!

Saturn nearly overhead must be fabulous!

Definitely works for me, but It's the stacking in the above mentioned order that really makes the difference.

Saturn overhead look amazing, even if it was 50 or 60 degrees above the horizon, it is not as crisp as having it over head. A few months ago when jupiter was overhead, there were a couple of nights where I saw the tiniest details within the cloud bands, the GRS was like a jewel popping out of soup and believe it or not, there was a darker spot visible within the center of the GRS. Fine line throughout the cloud bands, different shadings and a white oval too. The moons looked like discs not point of light... I think that if a planet is not overhead (with the exception of Venus and Mercury due to no choice) than I don't expect too much detail.

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39 minutes ago, MarsG76 said:

Saturn overhead look amazing, even if it was 50 or 60 degrees above the horizon, it is not as crisp as having it over head.

Looks like you have it at 78 degrees this year so the views must be amazing, particularly surrounded by all those treasures in Sagittarius! Jealous? Moi? You betcha! ?

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2 minutes ago, Stu said:

Looks like you have it at 78 degrees this year so the views must be amazing, particularly surrounded by all those treasures in Sagittarius! Jealous? Moi? You betcha! ?

Sagittarius... yeah, a couple of months ago I had a particularly good seeing, dark night when Scorpius and Sagittarius were on show hig above head... I was testing a spot on my property where it blocks all street and house lights. The views I had through the 14" dob were astonishing... the Swan was almost lost with in the fain nebulosity around it, the lagoon was massive and the structure visible on short photographic exposures were easily visible, except they were grey not color, the eagle nebula had the darkening where the pillars of creation are.. so close to seeing them... the trifid was obvious as, even the "blue" nebula part was just barely, but visible.... there is something mesmerizing seeing the DSOs so distinctly when there is that slight shimmer of stars and you see it alive.

Outside of Sagittarius the Sombraro galaxy had the shape, the dust lane visible, the omega cluster was a shimmering ball of millions of stars granulating all the way to the core, and the Carina nebula... if anyone has never seen the Carina nebula through a telescope using a UHC filter, than they are simply missing out....  

Not every night I'm out I get views like those, actually they are quite rare, but the night where it does happen its something that gives me goose bumps, and a hunger for more.

 

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19 minutes ago, Stu said:

Looks like you have it at 78 degrees this year so the views must be amazing, particularly surrounded by all those treasures in Sagittarius! Jealous? Moi? You betcha! ?

When talking about being jealous.. you have got a lot of goodies up there that I would love to get my gear onto... basically grass seems like its always greener on the other side, but in reality grass is green there where you water and feed it.  There is no one best place to be for astronomy...

Edited by MarsG76
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2 hours ago, MarsG76 said:

When talking about being jealous.. you have got a lot of goodies up there that I would love to get my gear onto... basically grass seems like its always greener on the other side, but in reality grass is green there where you water and feed it.  There is no one best place to be for astronomy...

Very true indeed :) 

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