Ganymede's transit of 11-25-00

by Jeffrey D. Gortatowsky


I got a few ancient photons on Friday (11.24.00) and Saturday (11.25.00) nights.

On Saturday we had one of those magical nights at the Orange County Astronomer's Anza site a 25km from Palomar Mountain. Just great great seeing. I'd say an 8 on a 1 to 10 scale. And it was timed just perfectly to coincide with Ganymede's attempt to put a pimple on a Jupiter.

I have never, ever, had the 18" (45cm) LITEBOX perform as well as it did Saturday. Boy oh boy it just goes to show how much the atmosphere really limits our optics. And maybe just a tad of star test collimation... :)

Full aperture with 7mm and 6mm Pentax SMC orthoscopics, and a 4.8mm Nagler, Jupiter displayed a wealth of detail. More than I can describe or sketch. And if the 4.8mm Nagler is not the most UNDERATED high power eyepiece in the world, I don't know what is. Every time I pop that ocular in it gives me goose bumps to see the detail it is capable of displaying (when conditions allow). Much better IMO than the 4mm Takahashi Ortho which by comparison seemed dim as if looking through a ground glass viewfinder on a camera. Don't believe the net pundits. Either the 4.8mm Nagler is a great great ocular, or I got an exceptional specimen, or I know squat about good optics. Take your pick.

Jupiter at full aperture in the 18 was amazing. Ganymede I thought displayed some sort of subtle shading in the northern hemisphere. I was especially prevalent just as the pimple was leaving the disc of Jupiter. My observing partner was not so sure. He thought I might be seeing some sort of contrast 'illusion'. What with the moon's shadow so close and the contrast of the light yellow/cream colored moon and the brown cloud band, he might be right.

Jupiter... wow. Three white ovals in the StB (I think that's correct), the GRS now a bit pinker or maybe slightly orange with cyclonic (circular?) details around the edges. Some weird looking disturbance in the NEB with a 'black eye' appearance. Dark edges and a light brown or white inner area. It had two prominent festoons jutting from it. It was being preceded by a large area of 'swirling' clouds with a prominent white diagonal gash. Some sort of brighter white area wall rolling along the southern edge of the NEB as well.

Well I won't bore you with more unscientific nomenclature. I don't have my logs with me, so I am writing this from memory. I did use a copy of the S&T article on observing Jupiter that ran a few months ago as a guide. Needless to say, I am please I was able to see the 18", for the first time since I've owned it, really live up to near it's full potential on details. And all thanks to the seeing being just right at the right time. I imagine my AP 130EDT would have been magical to use. Alas, being new moon weekend, it did not make the trip with me.