Questions regarding devices used to track and display the current time.

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2
votes
1answer
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Hour angle sunrise calculation problem

I am trying to program a sunrise/sunset calculator using this formula tutorial. If you follow the steps, eventually you get to this formula for "H" (the "hour angle"): $H = \arccos( [\sin(-0.83) - ...
7
votes
1answer
46 views

How would the pocket cellular clock work?

In a museum in Lviv, I saw a pocket cellular clock. I don't have a photo, but it was a small disc that had 2 or 3 filaments in it which were pointed at the stars (one of them was Andromeda, I think). ...