sensor-watch/movement/lib/astrolib

Astrolib

This is a relatively straightforward C port of Greg Miller's JavaScript astro library, done by Joey Castillo, for the Sensor Watch Astronomy watch face.

He released his work into the public domain and so I release this into the public domain as well.

I have tested the output of this library against NASA's Horizons system and found the results to match (within reason, as we're using a truncated version of VSOP87). Moon calculations still seem a bit iffy, but it doesn't surprise me seeing as there are three calculations involved and the error could stack up.

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