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Message started by jgfusco3 on 03/04/15 at 18:54:00

Title: Io and Europa
Post by jgfusco3 on 03/04/15 at 18:54:00

Hi Tony,
I was taking video images of the eclipse of Io and Europa around 11:00 to 11:30 on 2/28/2015. When I processed the images the images of a few videos show a 3rd object. I'm trying to determine if it was some type of reflection or the moon Amalthea. I was trying to view  Jupiter from more a earth location with the simulator to see if Amalthea was in the location or maybe another moon.



Title: Re: Io and Europa
Post by Tony on 03/04/15 at 19:53:18

Gravity Simulator 2.0 can not show you Jupiter as seen from Earth.  However, the latest version, still in development can.

Here is a simulation from the latest version of Gravity Simulator.  It runs in your browser so there is nothing to install.

This shows the moons of Jupiter.  The data was taken from JPL Horizons for March 1, 2015, 4:15 AM (GMT), or Feb 28, 11:15 PM Eastern Standard Time, which is about 15 minutes after your picture if I interpreted your time correctly.  So the positions of the moons should be accurate.

This new version is far from finished, buggy, and the interface is not yet user friendly.  But do the following:
Scroll down.  Below the initial image you see, there will be another image below it.  Initially, this image will be all black.
Press the Play button [>] on the time step control.
You will see Jupiter as viewed from Earth.

On the top left corner is a button that says [...]
Press it.  It opens a menu.  Choose "Labels" (8th button from top).
A labels interface should appear.
Click the checkbox so you can see the names of the objects.
Press the [...] button, now on the bottom of all the menu buttons, to make the menu disappear.

The "Field of view A" interface should let you zoom in.
Refresh your browser if you want to start over.

It looks like Amalthea is in front of Jupiter's disk at the time of your picture.
This sim includes all of Jupiter's 61 known moons.
Perhaps your mystery dot is a lens flare, or a background star.
In the future I'm going to add background stars to the program.

Title: Re: Io and Europa
Post by jgfusco3 on 03/05/15 at 06:10:23

Hi Tony,

It seems like fire fox works the best. I'm unable to get labels to work though. Also the the time frame, can I move it prior to 11:15P? I trying to see the alignment of the eclipse. It appears 11:15P is after the event.
I also see a object nearer to Juipter what moon is that?
I would like to display this at my astronomy club tomorrow night.

I ran the other simulator and I see Thebe Europa and Io??



Title: Re: Io and Europa
Post by Tony on 03/05/15 at 07:03:31
Try this.  I backed it up 4 hours to 00:00:00 GMT March 1
I just tried Labels in Firefox.  Worked fine here.  Try again.  Make sure you are scrolling to the bottom image.  It's off the page.  The image you initially see is not the one you should be looking at.

Title: Re: Io and Europa
Post by jgfusco3 on 03/05/15 at 17:41:12

Nice work, The image appears to be a error when the video was processes.


Title: Re: Io and Europa
Post by Tony on 03/05/15 at 22:10:44

Running the above simulation, it confirms what MikeBOKC said on the Cloudynights forum:  Europa occulted Io, and shortly later Europa's shadow covered Io.  After the occultation, switch "Camera Object A" to Sun.  A shadow event should be an occultation to an observer on the Sun.

Have you considered trying to image Amalthea or any of Jupiter's other small moons?  After a quick Google search, I can't find any amateur images of this moon.

You could set your telescope to track Jovian tracking rate, and then image Amalthea with a long exposure as it stalls at maximum separation from Jupiter.

Let me know if you want help determining the best times.  Because Jupiter's fast spin pulls it out of round, you can't propagate the above simulation into the distant (a few days) future.  You need a fresh set of orbital elements from JPL, as Gravity Simulator considers Jupiter to be a sphere.

Title: Re: Io and Europa
Post by jgfusco3 on 03/07/15 at 16:38:08

Hi Tony,

That sounds great. I will this weekend is a bit difficult because of weather. I plan for maybe next or the other weekend pending on weather over NJ.
This will be a challenge because to see the smaller moons will require a large scope or stacking and exposure besides tracking.


Title: Re: Io and Europa
Post by Tony on 03/11/15 at 20:43:07

It takes a few minutes to update to fresh elements.  Any time that's good for you, just give me a day's notice.  Jupiter opposition would probably be the best time to attempt it.

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