NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Time and Longitude by Jupiter's moons
From: Peter Monta
Date: 2024 Dec 08, 12:52 +0000
From: Peter Monta
Date: 2024 Dec 08, 12:52 +0000
I observed an occultation of Io once, about ten years ago. Funny story: I got the predicted time from Stellarium and went outside with my small telescope (a 90mm Maksutov-Cassegrain). I had previously modified an eyepiece with a small piece of aluminum foil in the focal plane to mask out the glare from nearby Jupiter.
So far so good, and I could see the moon just fine. The appointed time arrives, and nothing whatsoever happens. I start to think: uh-oh, perhaps the prediction doesn't take into account the light-travel time. I knew it had to be at least 15 or 20 minutes, but there wasn't time to go back and check, and I didn't want to miss the event. So I stuck with it at the eyepiece for something like 45 minutes. You end up feeling very foolish in this situation.
Finally it dimmed and went out. Job done.
Cheers,
Peter
On Saturday, December 7th, 2024 at 9:30 PM, NavList Community <NavList@fer3.com> wrote:
Re: Time and Longitude by Jupiter's moons
From: Sean C
Date: 2024 Dec 7, 16:58 -0800Reading these posts has rekindled my interest in finding the time by Jupiter's moons. After Frank helped me learn to do lunars, I thought about observing the Galilean moons, but never got around to it.
Now I have a 120mm refractor (pictured below) with a maximum useful magnification of about 280x. I have seen the moons many times, I just haven't timed their eclipses.
If I do find my bag of round tuits, I'll certainly post my results here.
Cheers!
Sean C.
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