Jovian shadow transits

Hey, just wondering if I should expect to see the three shadows crossing Jupiter this weekend in a teeny 4.5" reflector? In dark skies and good seeing I can always make out the major two dark bands and sometimes several other bands... I think my collimation may be off a little, too (don't have any tools for this).

Just wondering if I should try or attempt to look through someone else's scope. Sounds like a great sight!

-Ken

Those black dots across the face of Jupiter are pretty small. Assuming you can push your magnification 50x per inch, the best you could reasonably expect under good conditions is about 225x. If you say your collimation's off, I'd reduce that by a percentage of, say, 25%, which would bring it down to 165x. Your image would also be darker as you push the magnification, and you'd want to maximize contrast as much as you can. Your best view would be a compromize somewhere between high magnification and the contrast you'd get with lower power. Unless you've got young eyes, I'd recommend hanging out with someone with more aperture to guarantee seeing the transits. But keep your scope handy and see how it works!

Good luck!
Howard

Jovian transit shadows are easily seen in my 75mm refractor at ~80x (and likely lower).

By all means, TRY.

Best wishes and luck.
-Dan

You will find the answer in this post

http://www.cloudynights.com/ubbthreads/showthreaded.php?Cat=&Number=64769&page=1&view=collapsed&sb=5&o=&vc=1

Typically, moon shadow transits can be detected at 1/3 to 1/2 your normal scope resolution.

It would be much more difficult to see the moon preceeding the shadow across the face of the planet disk. It would be even far more difficult to see the moons as disks. Read here for that info.

http://www.cloudynights.com/ubbthreads/showthreaded.php?Cat=&Number=65250&page=1&view=collapsed&sb=5&o=&vc=1

Your 4.5" scope will easily show you the larger shadow transits even at fairly moderate magnifications and will show the smaller moons at higher power and is more than enough to resolve the larger moons to a true disk.

Ganymede's and Callisto's shadows might be seen with magnifications as low as 125x, even with an 80mm scope.
You might expect magnifications to be
160x-180x to see Io's shadow and
175x-200x to see Europa's shadow

edz