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JPL Horizons - "highly accurate measurements of planetary positions" - how do they do it?

@PM2Ring's answer does a great job of explaining that folks who do careful numerical integration keep a large number of digits beyond the final accuracy because if they didn't, after tens of thousands ...
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JPL Horizons - "highly accurate measurements of planetary positions" - how do they do it?

The JPL ephemerides are good, but they certainly are not precise to the fraction of a millimetre! From the Horizons docs: Statement of Ephemeris Limitations To produce an ephemeris, observational ...
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2 votes

How can you derive equations between the Horizontal and Equatorial system if the two systems have different centers?

This might be a dumb question. This is an excellent question! When we watch a solar eclipse, or the occultation of a star (or planet) by the Moon, and we want accurate timing information (or we want ...
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