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Old 25-11-2010, 05:50 PM
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The Observologist

ngcles is offline
Join Date: Dec 2006
Location: Billimari, NSW Central West
Posts: 1,566
Originally Posted by pgc hunter View Post
Hey Les, great to hear from you again! This would've been a great opportunity to go after some of the tiny HSB summer PNs, and NGC 3918 in seeing like this, it's fun trying to eek as much detail as possible. Always wanted to go after 3918 in excellent conditions. I later looked up images of 2440 to compare to my own obs and discovered that the outer plumes of the PNe extends about 2x further than the parts I saw, something to try for next time.

On a related note, someone on CN claimed to see detail on Neptune (with an 11" scope IIRC) under what he describes as *perfect* seeing, it seems a little far fetched but would it really be possible

Ganymede and Neptune are approximately similar sizes with Neptune a little bigger, but Ganymede has a brighter colour which presents as better surface brightness and the contrast on detail would, I'd think, be markedly better though neither would be described as a "walk in the park" basically due to size. I'd be sceptical too, though it's not outside the realms of possibility to see limited detail on Neptune in 28cm. BTW, what's an "IIRC" ??

Have seen Himalia -- tracked it down some time ago now it is by some distance the next easiest Jovian moon after the four big ones and not hard to see in 46cm in good conditions. The trick is finding the correct location/field and distinguishing it from a 14th-odd magnitude star. There is an ephemris here:

if anyone is interested.

It is obviously easiest at greatest elongation from Jupiter. If you can find Pluto, Himalia won't present many issues. It orbits well outside Callisto meaning you can exclude Jupiter from the field with ease during most of its orbit. Jupiter is heading north over the next few years which will make it harder as it is closer to the horizon and the air-mass you are looking through is greater. On the other hand, Sagittarius also presents problems of its own because of the blizzard of 14th mag stars it will be hiding among. Now could be a good time ...


Les D
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