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[cosinekitty]

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[gerben-b]

Hi Don,

I seem to be the first here. My name is Gerben Bijhold and i am interested in moon and planet photography. For that purpose I built a web based app to control my camera and my telescope. The camera controls are fine now but the telescope control is still a challenge. In my app I also show the moon as it appears in the sky, but lately it has been too cloudy to check that. Hopefully, I will be able to do that soon.

Enough about me (or my app). I want you to now that I am quite impressed with your project here on github.

Cheers now,
Gerben

[cosinekitty]

That is perfect! I will see if I can build that Go code and generate some test data.

[cosinekitty]

@meshula I looked at the soniakeys/meeus repo. The code for Jupiter's moons looks promising. It has two different models, a simple one and a complicated one. Both calculate the 4 major moons relative to Jupiter's equatorial plane. The simple one treats the moons as always exactly in that equatorial plane, calculating x and y values only, with z=0 always. The complicated one includes their slight movement above and below the plane.

Because you have the Meeus book and I don't, I'm wondering how I can convert Jupiter's equatorial plane into another coordinate system that Astronomy Engine can handle. Is there some mention of how to convert the Jupiter frame of reference into Earth's equatorial plane, or the plane of the ecliptic? In other words, I could translate her code from Go into other languages, and get some numbers, but I don't know how they relate to any of the existing things I calculate. I hope I'm making sense...

[gerben-b]

Update: I just check Amazon, and the cheapest I can find that book is over $300 US. WOW!!! It's a collector's item...

I went looking too, and found them cheaper, e.g.: https://www.willbell.com/math/mc1.HTM. I even found a free pdf, but I'm not sure if that is legal, so I ignored that.

Anyway, the proceedings seem promising. As soon as Jupiter is visible from my window I'll start observing those 4 moons to see if I can capture their movement with a time lapse of a couple of hours.

[cosinekitty]

I clicked on that link, but then I see: "Willmann-Bell is closed for business. Orders will no longer be accepted."

[meshula]

To make it easier to follow, I started a new thread for Jupiter's Moons with a couple of breadcrumbs, including a link to the specific calculations in Chapter 43 needed to compute the variables needed for Chapter 44, and a description of the coordinate system. #97