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Anyone else catch the double transit this morning?

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#1 Ed D

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Posted 03 October 2013 - 01:29 PM

Weather down here in 'Sunny South Florida' continues to be horrendous. However, this morning at 4:30am (UT -4) wasn't that bad so I set up my little Vixen, made a cup of coffee, and started observing Jupiter through the only decent open spot in the sky. I noticed that one of the moons was near the planet and I was in for a little treat. What surprised me was when I realized that I was observing a double transit. Io's shadow was pretty distinct, while Ganymede's shadow was less prominent and a little harder to observe, at least in my 70mm achro and not so great conditions.

Good thing the clouds finally drifted enough to obscure my view of Jupiter. I didn't realize just how long I had been outside observing this double transit treat. I had to rush through my morning routine to try to make it to work on time.

So, was anyone else lucky enough to catch this?

Ed D

#2 Ed D

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Posted 03 October 2013 - 01:43 PM

There is a fantastic pic of the transit HERE in the Solar System Imaging forum.

Ed D

#3 C_Moon

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Posted 03 October 2013 - 08:55 PM

I also viewed this morning and thought it was a double shadow transit as well. Turns out it was Ganymede transiting and Io's shadow!

I have never seen a moon transit that was that dark before. Usually I "lose" the moons after shortly after they move past the limb.

I'm not sure if I ever saw a Ganymede transit before. Is it always that noticeable as it traverses the disk of Jupiter?

I did not notice that Ganymede was over Oval BA, but I did think that the shape of the transiting Ganymede was not quite circular, so perhaps I was seeing some detail of Oval BA superimposed next to Ganymede?

By the way, I also saw a prominent white spot (almost looked like a bubble to me) in the equatorial band. From looking at the image you linked to, I believe it was the large festoon/plume NE of the shadow.

#4 Ed D

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Posted 04 October 2013 - 12:48 PM

Paul, you're right, it was Ganymede transiting and Io's shadow. I found a pic that was taken later than my observation. It showed the two moons off to the side of the planet, and Ganymede casting a shadow. It figures that I can't find it now! If I do come across it again I'll post a link.

In the transits I have observed the moons look like bright disks and the shadows are inky black. This is the first time I have observed a moon that looked a fuzzy pale grey.

I also noticed the feature right next to Ganymede, which later I identified as the Oval BA from the pic. Howver, I didn't see the white spot in my scope, but doubt I would have in a 70mm achro.

It was a great way to start the day, observing something I had not seen before.

Ed D


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