Re: ATM Another optics test - Jupiter's moons

[spooner@page.az.net (Michael Spooner)]

Tom Krajci wrote:
> 
> Saturday night I had the chance to show my 4.25 inch f/11 optics at
> the local astro club meeting.  We observed with this scope a transit
> of (I think) Ganymede across the face of Jupiter.  This took place
> Sat. night in Louisiana, but that's about 0100-0330GMT, 17 Aug.
> 
> It was easy to see the shadow on Jupiter, but I was also surprised at
> how easy it was to see Ganymede on the face of the planet too!
> 
> Here's the question:  As a way to evaluate optics/observers/seeing
> conditions, are all the gallilean satellites equally easy/hard to see
> transiting the face of Jupiter?  If not, which ones are easier than
> others?  What's the smallest scope aperture you would need to see a
> moon against the backdrop of Jupiter?
> 
> No, this is not a quantitative test, but we do make telescopes for
> observing. . .don't we?  ;-)
> 
> Tom Krajci
> 
> Capt Tom Krajci
> B-52 Intelligence Officer
> "In God we trust, all others we monitor!"
> http://spur.barksdale.af.mil

I went out to glance thru scope at Jupiter. The seeing was stable enough 
to video the event. The moons sometimes (more often than not - so it 
seems <g>) transit across a belt instead of a light zone as last night. 
This makes them much more difficult to spot in mediocre seeing. Aren't 
those longer focus mirrors nice to use though? ;-) And fun to make just 
to keep this in an ATM type discussion.

Mike Spooner