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Old 07-07-2017, 10:03 AM
Tropo-Bob (Bob)
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Saturn's Moons

I have been observing Saturn's moons with a variety of small refractors. I can see Rhea (2nd brightest moon) with an 80mm scope, although 100mm is better. It is interesting to follow each evening, as it moves so rapidly around the planet.

However, even with a 100mm, Dione and Tethys are rather difficult and I will need to use a bigger scope to follow these more seriously.

From what I have seen though, these both look rather alike. Can they be told apart easily? I know each of Jupiter's moons by sight and would like to obtain the same skill with Saturn's Moons. If anybody can do this, please advise if the slight difference in brightness is the clue, or simply the moons distance from Saturn.

Last edited by Tropo-Bob; 07-07-2017 at 10:40 AM.
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Old 07-07-2017, 01:34 PM
deanm (Dean)
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It's easy to tell them apart: all you need is $2 billion dollars, a sophisticated spacecraft and a powerful launch vehicle..!
https://apod.nasa.gov/apod/ap170706.html
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Old 07-07-2017, 06:56 PM
Tropo-Bob (Bob)
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Originally Posted by Tropo-Bob View Post
.

However, even with a 100mm, Dione and Tethys are rather difficult and I will need to use a bigger scope to follow these more seriously.

From what I have seen though, these both look rather alike. Can they be told apart easily? I know each of Jupiter's moons by sight and would like to obtain the same skill with Saturn's Moons. If anybody can do this, please advise if the slight difference in brightness is the clue, or simply the moons distance from Saturn.
I observed these tonight and correctly guessed which moon was Dione because it was more distant from Saturn than was Tethys. I used an 8" SCT with a 16mm Brandon EP. (I tried several others, but the Brandon seemed to show fainter objects- only by a fraction and this opinion is very subjective). I will follow these moons more often and hopefully with practice , I will not need to guess in future.

I looked for Encelanus and failed to see it, even after consulting a program displaying where it is. The near full Moon only about 6 degrees from Saturn certainly did not help, so I will try again when there is no Moon.

Last edited by Tropo-Bob; 08-07-2017 at 07:03 AM.
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Old 18-10-2017, 08:05 AM
Tropo-Bob (Bob)
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Its been a learning adventure watching Saturn's Moons this year.

I used to be able to identify Titan, see other Moons, but not know which moon was which. Now I can find Rhea with an 80mm refractor, although a 100mm is much more comfortable.

With the 100mm, I can just see Tethys and Dione, but really cannot tell them apart without consulting where each is predicted to be.

I did find Iapetus at maximum brightness and marvelled on its extremely wide orbit.

After waiting years for the rings to be wide open, now I am waiting for them to close, because from previous experience, I found the Saturn's Moons to then be more easily seen. What do they say about grass been greener?
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Old 18-10-2017, 01:34 PM
Kunama
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We had a bit more aperture last night and managed Titan, Rhea, Tethys, Dione and Enceladus, didn't look for Hyperion or Iapetus ..... maybe tonight ....
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Old 03-11-2017, 09:24 AM
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Tinderboxsky (Steve)
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Interesting exercise Bob. I shall try next year as Saturn’s opposition approaches.
This reminds me of my little project to bag a detailed observation of each of the 11 events for the Jovian moons; occultation - disappearance & reappearance, eclipse - disappearance & reappearance, transit - ingress, transit & egress, shadow - ingress, transit and egress and a concurrent moon and shadow transit.
I have bagged a good observation of each of these events, except for Callisto where i am missing an occultation disappearance, a shadow egress and a concurrent moon and shadow transit. Because of Callisto’s wide orbit these only occur approximately every 6.5. when the orbital plan lines up with Earth. I have to be patient till some time in 2020/21, I think before I can complete all of these observations.
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Old 29-01-2018, 08:19 AM
Tropo-Bob (Bob)
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Originally Posted by Tinderboxsky View Post
Interesting exercise Bob. I shall try next year as Saturn’s opposition approaches.
This reminds me of my little project to bag a detailed observation of each of the 11 events for the Jovian moons; occultation - disappearance & reappearance, eclipse - disappearance & reappearance, transit - ingress, transit & egress, shadow - ingress, transit and egress and a concurrent moon and shadow transit.
I have bagged a good observation of each of these events, except for Callisto where i am missing an occultation disappearance, a shadow egress and a concurrent moon and shadow transit. Because of Callisto’s wide orbit these only occur approximately every 6.5. when the orbital plan lines up with Earth. I have to be patient till some time in 2020/21, I think before I can complete all of these observations.
Steve, I never noticed your reply till now. I admire your organised approach and this now prompts me to taking a similar approach to make sure that I see all the Jovian events. Yes, thanks, because I was also wondering when Callisto was to again be in play.

I really enjoyed breaking the 'new' ground with Saturn last year. However, I was not happy with my grab and go setup, but that has now been corrected.
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Old 29-01-2018, 08:23 AM
Tropo-Bob (Bob)
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Ok, now I remember why I don't add photos. (See upside down pictures in previous post).

Can anybody advise me how to rotate these pictures?
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  #9  
Old 29-01-2018, 07:35 PM
bigjoe (JOSEPH)
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Quote:
Originally Posted by Tropo-Bob View Post
Ok, now I remember why I don't add photos. (See upside down pictures in previous post).

Can anybody advise me how to rotate these pictures?
Bob sometimes if you just crop etc it may modify the oridinal camera info , also changing resolution tone etc...this can make it possible to go right side up..bit of an experiment when posting from Android etc.

Lots are having same problem ...once original image is modified it can sometimes solve this recurring issue.
Just no strict rules going from platform to platform always some issue.

Try posting it upside down and see if it goes right side up posted..who knows ..some people actually get annoyed by this issue.
bigjoe.
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Old 29-01-2018, 07:38 PM
bigjoe (JOSEPH)
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Originally Posted by Tinderboxsky View Post
Interesting exercise Bob. I shall try next year as Saturn’s opposition approaches.
This reminds me of my little project to bag a detailed observation of each of the 11 events for the Jovian moons; occultation - disappearance & reappearance, eclipse - disappearance & reappearance, transit - ingress, transit & egress, shadow - ingress, transit and egress and a concurrent moon and shadow transit.
I have bagged a good observation of each of these events, except for Callisto where i am missing an occultation disappearance, a shadow egress and a concurrent moon and shadow transit. Because of Callisto’s wide orbit these only occur approximately every 6.5. when the orbital plan lines up with Earth. I have to be patient till some time in 2020/21, I think before I can complete all of these observations.
That reminds me Steve to check for the next Ganymede transit even the shadow transit..always enjoy that one ..see if I can resolve a disk next time..some say the've seen features visually on it.
bigjoe.

Last edited by bigjoe; 29-01-2018 at 07:39 PM. Reason: Add
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