What's the smallest telescope to show the cassini division?

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jrkirkham United States of America
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What's the smallest telescope to show the cassini division?

#1

Post by jrkirkham »


I know that in a large pair of binoculars at around 20x the rings of Saturn look like "ears" as Galileo described them. Here's my question. What is the smallest telescope and least amount of power that you have used and still been able to make out the Cassini Division? :telescopewink:
Rob
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Re: What's the smallest telescope to show the cassini division?

#2

Post by JayTee »


My smallest scope that accepts eyepieces is a 70 mm f/5.1 refractor. I'll give it a try and report back and tell you what magnification was needed if it's visible at all.

Cheers,
JT
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Re: What's the smallest telescope to show the cassini division?

#3

Post by Thefatkitty »


Hi Rob, your timing on that was good, at least for my answer :D

The other week it was exceptionally clear one night, and using my old orange C80 at 910mm f/l and a 12.5 Fujiyama KK, I was able to pick out the Cassini division on Saturn and the GRS on Jupiter. I don't remember it being so prominent through this scope that night!

So all that to say, I got away with 73X, if I'm doing the math right. Hope this helps! :D

All the best,
Mark

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Re: What's the smallest telescope to show the cassini division?

#4

Post by JayTee »


Okay,

Based on tonight's observations using a 70mm refractor at 400mm FL, seeing was a solid 3. The setup was the frac mounted on top of my CPC1100. This is a very stable platform and nothing at all like a cheap "intro" mount. We all know that anything above about 50X will have severe shakes when using an "intro" mount. Additionally, I'm an experienced observer meaning I already know where to look and what it should look like, plus I know to be patient at the EP and let the seeing do its thing. With all that, here's what I got.
Cassini.jpg
The 6 and 4.5mm EPs are 2X balowed 12 and 9mm EPs respectively. I don't own any decent EPs shorter than 9mm. At 67X I think I was convincing myself that I was "probably" seeing it. On a steadier night, it may have been visible.

It was an interesting little exercise.

Cheers,
JT
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Re: What's the smallest telescope to show the cassini division?

#5

Post by jrkirkham »


Wow JT! That is an extremely interesting chart. Now you've got me interested in looking for the rings with my binos.
Rob
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Re: What's the smallest telescope to show the cassini division?

#6

Post by Lady Fraktor »


To see the actual Cassini Gap requires a high quality telescope in the 150mm-200mm range with excellent skies.
The dark area between rings A and B (Huygens Gap to Cassini Gap with various smaller rings between the two) referred to as the Cassini Division can be done using a smaller telescope as it appears to be a dark gap but is not.
Saturn Rings 1.jpg
Saturn Rings 2.jpg
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Re: What's the smallest telescope to show the cassini division?

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Post by jrkirkham »


That view is way beyond anything I've ever seen. It is interesting. Thanks for posting this closeup of the rings and gaps.
Rob
Telescopes: 50mm refractor, ED80 triplet, 90mm makcass, 10" dob, 8"SCT, 11"SCT
Mounts: Celestron CGX, Orion Sirius + several camera tripods
Cameras: Canon 6D, Canon 80D, ZWO-ASI120MC
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Observatory: SkyShed POD XL3 + 8x12 warm room
AL Projects Completed: Lunar #645, Outreach #0280, Universe Sampler #93-T, Binocular Messier #871, Messier #2521, Messier Honorary #2521, Constellation Hunter Northern Skies #112, Planetary Transit Venus #1, Galileo #26, Outreach Stellar 0280, Meteor Regular #157, Solar System Telescopic #209-I, Observer Award #1
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Re: What's the smallest telescope to show the cassini division?

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Post by notFritzArgelander »


jrkirkham wrote: Tue Aug 25, 2020 6:19 pm That view is way beyond anything I've ever seen. It is interesting. Thanks for posting this closeup of the rings and gaps.
I did see the Encke Gap with a 1 meter RC and ~600-800x.
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Re: What's the smallest telescope to show the cassini division?

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Post by helicon »


I did make out the Cassini division with a 5.1" newtonian - so far the smallest scope that I have used to observe it.
-Michael
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Re: What's the smallest telescope to show the cassini division?

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Post by MistrBadgr »


One of the most memorable views I have had of Saturn, showing the dark gap between the A and B rings with distinct edges, was with a 60mm f/15 refractor that, I believe, was made in Japan for Meade. It had a wooden tripod with a significant portion of the black paint gone off of it due to age. Otherwise, I am not sure of a model number. The angle of the rings was about as wide as it gets, I think, at the time. I do not remember what the power was, probably not over 90x or less than 60X.
Bill Steen
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Re: What's the smallest telescope to show the cassini division?

#11

Post by MistrBadgr »


Lady Fraktor wrote: Tue Aug 25, 2020 6:00 pm To see the actual Cassini Gap requires a high quality telescope in the 150mm-200mm range with excellent skies.
The dark area between rings A and B (Huygens Gap to Cassini Gap with various smaller rings between the two) referred to as the Cassini Division can be done using a smaller telescope as it appears to be a dark gap but is not.

Image Image
Just looking at your pictures, I want a scope like yours! :telescopewink:
Bill Steen
Many small scopes, plus a Lightbridge 12, LX 70-8R,6R,6M
Many eyepieces, just not really expensive ones.
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Re: What's the smallest telescope to show the cassini division?

#12

Post by messier 111 »


https://www.britannica.com/science/Cassinis-Division

https://www.nasa.gov/mission_pages/cass ... 06196.html

from what i can understand it is very difficult to see the cassini division.
I thought the first division was cassini,
not like encke, which is hard to see.
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