Double Moon Transit with a Twist

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Apollo XX
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Double Moon Transit with a Twist

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Howdy Folks,

Here's one for our intrepid group of winter-weary observers; Tomorrow evening, on the 16th of March there will be a double moon and shadows transit on Jupiter. Io and Ganymede will cross the planet's disc and drag their shadows across behind them. Now I know many of us like to enjoy this little celestial phenomena, and it's not necessarily a challenge for our more seasoned observers, so why would I put it out as one? Because this particular event begins long before it gets dark - even before the sun sets!

Here's a graphic of what will be happening at a little past 6:30pm local time:

Image

You're looking at the positions of the moons at 6:38pm, while the sun sets at 6:52pm. The challenge here is to see how early on in the event you can pluck out the shadow transits. Jupiter itself shouldn't be overly difficult to find if you've been keeping an eye on it lately, but it wouldn't hurt to practice this evening to better your chances of getting an early start. I've been looking at Jupiter a lot recently and have a general idea where it will be before it gets dark, but I'm still planning to go out this evening and establish some triangulation to better my odds of quickly landing it tomorrow. The weather forecast for the timeframe involved here looks favorable, with clear tonight and partly cloudy conditions early tomorrow night. Even if it's a struggle early on, hang in there. The shadow transits don't end until just past 8:00pm.

Can you see the moon shadows in broad daylight? Have you in the past? If you have in fact seen this before, or if you have tried before, please consider sharing it with us here. If everything comes together I'll be out there, eye glued to the eyepiece, seeing what I can see. Just the thought of someone seeing me standing there staring into the scope while it is aimed at an apparently blank area of blue sky makes me laugh. It brings back the memory of my daughter walking up to me one time while I was viewing Jupiter through relatively thick cloud cover and she said "can you even see anything in there"? In fact I could, but most people wouldn't understand.

So how 'bout it, who's up to the challenge? if you do give it a try, please share your experience with us.

Mike M.
"The purpose of life is the investigation of the Sun, the Moon, and the heavens." - Anaxagoras
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Apollo XX
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Re: Double Moon Transit with a Twist

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Update: The daytime Jupiter practice viewing went well, and I'm confident of success if the sky holds. At 5:45pm last evening I put the base of the scope on the mushy ground and used foot pressure to press it into a level setting. Consulting Stellarium I found that Jupiter was at an altitude of 57* and change. Using a 32mm eyepiece for a 1.5* TFOV, I set the altitude and panned the azimuth. In just a couple of minutes I had Jupiter in view, with the sun still 15* above the horizon. The view was pretty good, and I immediately jacked the magnification up to 200x. Based on what I saw, I'm thinking the moon shadows could be reasonably visible, especially considering that it will be about an hour later when I try this evening. The sun will only be about 1* up at 6:38pm today, significantly darkening the sky toward the east.

Anyone else giving this a go?

Mike M.
"The purpose of life is the investigation of the Sun, the Moon, and the heavens." - Anaxagoras
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AndyG
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Re: Double Moon Transit with a Twist

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I got it! 8)

Jupiter 2014/03/16 19:20

Image
Andy
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Apollo XX
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Re: Double Moon Transit with a Twist

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AndyG wrote:I got it! 8)

Jupiter 2014/03/16 19:20

Image
What's this, a venture into planetary imaging??? Awesome! I can't wait to see what you do when it's clear!

Mike
"The purpose of life is the investigation of the Sun, the Moon, and the heavens." - Anaxagoras
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Apollo XX
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Re: Double Moon Transit with a Twist

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So as you can see, Andy bagged the double moon transit, but I KNOW it wasn't easy. Of course this afternoon the sky went bad by 4:00, and any idea that Jupiter would be visible before sunset was just a fantasy. AARRRGH! Clouds, clouds and more clouds! :evil: I kept going out to give it the 'ol college try though, and I was finally able to acquire the planet visually at around 7:10pm. Could I see the shadows? Yes. Not well though, as Jupiter wasn't even remotely visible naked eye through the cloud cover. I finally got tired of playing the now-you-see-me now-you-don't game a little after 7:30 and packed it in.

So the carrot is still out there, so to speak. The attraction this evening was that it was a double transit in daylight, but there are several more opportunities to attempt a daylight shadow transit sighting coming up. For those that are interested in the challenge, you can try for Io's shadow on March 25 between 3 and 4 pm, Io's again on April 1st between 5 and 6 pm, and Europa's on April 7th between 5 and 6 pm.

I'd like to give credit to the folks at RASC, who made me aware of this event through their awesome calendar. https://www.rasc.ca/observers-calendar

And also thanks to Andy for coming onboard with the challenge. It was a wonderful surprise to click on this thread and discover your image!

Mike M.
"The purpose of life is the investigation of the Sun, the Moon, and the heavens." - Anaxagoras
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AndyG
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Re: Double Moon Transit with a Twist

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Apollo XX wrote: What's this, a venture into planetary imaging???
Yup, this is my first image attempt with a new planetary camera, a ZWO ASI120MM I just received on Friday!

The biggest challenge I had getting ready was aligning my finder scope. I had to put a finder on the scope specifically for this challenge and I needed it to be accurately aligned so I could pinpoint Jupiter at dusk and have it land in the 3x4 arcminute field of view of the camera. My yard is surrounded by trees in all directions and I had a heck of a time finding a stationary object in the distance that I could use as a reference point. I did find a tree about 150 yards away and managed to get focus on it. The problem is, the field of view is so tiny I could not figure out what part of the tree I was looking at! My wife suggested I put a marker on the tree, so I ran over to it and covered it with labelled 2" square sticky notes. I then nudged the scope around until I found a sticky note, then ran back to the tree and removed all but the one I identified through the scope. So then I could finally align the finder :shock: (the 2"x2" sticky note filled the field of view of the camera :P )

By then it was about 6:30, so I started staring at the sky. It was still clear, but thin clouds were starting to appear. By about 7pm I spotted Jupiter naked eye and had it centered in the finder by 7:02. I ran back to the computer screen and of course the planet was not in the field of view. Luckily it did not take long to find it by spiraling outward from the starting point. I took a moment to focus as best I could and started capturing frames at 7:20. After about 5 minutes of capturing the clouds had worsened to the point that I had to stop.

The image is a stack of the best 50% of about 1100 frames. Not the best Jupiter image out there but at least the 2 shadows are visible, so I am thrilled with that, and looking forward to trying some more when conditions are better. There is actually a moon just peeking out from behind the lower equatorial band at about 2 o'clock. There is also a moon about one Jupiter-diameter away at about 2 o'clock. Here's another version of the image with that moon brightened up so it can be seen.

Thanks for posting the challenge, Mike. It gave me a bit of excitement this afternoon going after it and playing "chicken" with the oncoming clouds.

Image
Andy
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Apollo XX
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Re: Double Moon Transit with a Twist

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Andy, you caught that image at the exact time I was looking at it visually from my yard. That's Io lingering on the limb, and that's one of my favorite things to see when viewing Jupiter. Of course last night's view would be best classified as underwhelming, but I saw it just the same so that's cool.

Looking forward to your upcoming adventures with the new camera.

Mike
"The purpose of life is the investigation of the Sun, the Moon, and the heavens." - Anaxagoras
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AndyG
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Re: Double Moon Transit with a Twist

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Here's a re-processed version, now you can see all 4 moons and the two shadows :!:

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Image
Andy
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Apollo XX
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Re: Double Moon Transit with a Twist

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Wow, that's a big difference! The very first image you presented is very representative of the view I had through the eyepiece, and now your re-processed result shows how much more the camera was able to see.

Is your new rig set up to gather color data too? I saw on their website that they market it with a filter wheel, but then you've probably got all that already.

Mike
"The purpose of life is the investigation of the Sun, the Moon, and the heavens." - Anaxagoras
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AndyG
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Re: Double Moon Transit with a Twist

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Apollo XX wrote:Is your new rig set up to gather color data too? I saw on their website that they market it with a filter wheel, but then you've probably got all that already.
I chose not to get the manual filter wheel option with the camera, but instead ordered a motorized filter wheel and filters separately. I wanted to have a way to control the filter wheel remotely from the scope. The new filter wheel and filters are expected to arrive tonight, so if things go well I may be able to try it tonight.
Andy
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