I have a 10" Dob and so far I have seen the 4 Galileo moons; Titan, Rhea, Japetus, Dione and Tethys (in Saturn); Titania and Oberon in Uranus; and Triton in Neptune. All are relatively easy although Tethys, Titania and Oberon are often a bit difficult.
So far I have failed spotting Enceladus (which shouldn't be that super hard), Ariel and Umbriel seem to be very hard to see, and I haven't tried to see Phobos and Deimos (I will in soon as Mars reaches opposition)
I guess I would rank the moons by difficult like this:
Super easy to see:
4 Galileo moons
Titan mag 8
Rhea mag 10
Japetus mag 10-12
Dione mag 10.5
Triton mag 13 (a fainter moon but the advantage is that Neptune is also fainter, at 15")
Tethys mag 11 (for me Tethys is always a bit more difficult to see than Dione)
Slightly challenging but seen under good conditions with a 10":
Oberon mag 14 (around 40" from Uranus)
Titania mag 13.5 (around 25" from Uranus)
Deimos mag 11 (around 50" from Mars) I have not seen it yet
Pluto mag 14.5 (it has no glare, so it is easier to see)
Challenging/ requires good seeing (I have not seen these ones with my 10" Dob):
Enceladus mag 12 but around 20" from Saturn
Even more challenging:
Phobos mag 11 but around 15" from Mars
Ariel (mag 14.5, around 15" from Uranus) I might have glimpsed this moon in one instance, but that was an unconfirmed case
Umbriel (mag 15, around 15" from Uranus) I have not seen it despite trying
Probably very difficult but still within the technical limits of a 10" under perfect seeing conditions:
Himalia (mag 14.5 and not too close to Jupiter but probably hard to spot in Jupiter's glare, max separation is 50')
Mimas (mag 13 but very close to Saturn, usually about 5" but max separation is 15")
Only reachable with much larger apertures
Charon (mag 16 and 1" away from Pluto - it would require very dark skies and perfect seeing)
Miranda (mag 16 and close to Uranus at 9")
Phoebe (mag 16.5 but about half degree from Saturn)
Amalthea, mag14 but too close to the very bright Jupiter at 30"
Nereid, mag 18 (3' away from Neptune) probably too faint for most
Any other moons?
Would you agree with this ranking? Any comments on moons that can be seen with a 10" or 12" aperture under perfect conditions?
Edited by Pcbessa, 04 August 2020 - 05:41 PM.