7 replies to this topic

[ButterFly]

So much Mars talk lately.  Don't forget that Uranus is coming near opposition this week (Oct 31).  It's a good chance to bag some more moons.

[chuckles]

I had no luck finding them the one previous time I made a half hearted attempt to do so. What size scope is the minimum needed? I assume you also need pretty good seeing? What are other’s experiences?

[SNH]

I had no luck finding them the one previous time I made a half hearted attempt to do so. What size scope is the minimum needed? I assume you also need pretty good seeing? What are other’s experiences?

I don't have my notes handy, but I have seen one moon of Uranus and suspected a second one with my 10-inch SCT. I should take the time to go for them again this winter. Since I'm mainly a DSO observer, seeing isn't all that important to me. But if I notice that it's pretty good, I'll sometimes go after a tight double star or some "distant moons" - which do require it more.

 

Scott

[Rutilus]

In the past I have seen two of the moons with my 6 inch f/8 achromat refractor.

Here is a drawing from a visual observation I made a few years ago.

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[Allan Wade]

Titania, Oberon and Ariel are not difficult moons, from a dark site at least, as Rutilus proves with his 6”. I never tried for Umbriel until I got the 32”, and it’s obviously an easy moon for that aperture.

 

Miranda is the last moon to observe on my solar system tour. I’ve tried once in good conditions using a 32” in Florida and didn’t see it. I’ve only had limited opportunities for one reason or another to try in my 32” over the last couple of years and have never struck seeing good enough to see it. Given I’m at 29 solar system moons now, and Miranda is giving me trouble, it puts into perspective how difficult it is to observe. It was only discovered in 1948 using imaging, so there’s a chance almost no one has visually seen Miranda.

[ButterFly]

Ariel is still fairly difficult in my 15".  I have yet to see Umbriel, which is surprising.  It's not that much dimmer and it's further away.  I will keep trying.  Failure is free here.

 

Night vision makes all four easy.  I kick the scope and they jiggle - that's still visual, right?  Even with the cheating, Miranda is always lost in the halo, even though Umbriel pops through it.

[Redbetter]

Unless the seeing is poor I can catch the four brighter moons in the 20" when I try, including in a red zone.  When the seeing is poor enough the inner two can go missing, otherwise I can find the four without knowing their positions in advance. 

 

I have seen the main four with an 8" mask on the 20", (in 5/10 seeing for the 8" aperture.)  I have little doubt that I could see Titania and Oberon with my 6" mask at a dark site, but I haven't tried it.  I have seen Titania and Oberon in the suburbs recently with the 8" SCT (didn't have positions ahead of time used a nearby star to confirm orientation was correct later.)

 

I have tried for Miranda a number of times with the 20", but never have succeeded.  Miranda is in the mid 16's, about 1.5 magnitude dimmer than Umbriel, and much closer to the planet.  Mid-16's is averted vision in the 20" even on very good nights, being close to Uranus which is 11 mag brighter has been too much to ask.  I would probably need a tracking scope and use my occulting bar in excellent seeing to have a chance (I've tried the occulting bar but have not been successful.)

[SNH]

Okay, so back during my five night run of observing, I spent a few minutes on Uranus. With only 263x in my 10-inch and no prior knowledge of their locations, I was a bit surprised to see Oberon without much fuss at +14.1 and 33" out. Then I suspected another one, which I confirmed with 525x and later learned was Titania at +13.9 and 25" out. I've been doing more gauging of the "seeing" these past few months since I've been observing/photographing Mars. I need to remember that if I catch a good night, I should try for Ariel (+14.3) while it's at its best separation (always under 20", though).

 

So thank you, ButterFly for the reminder!

Scott