The sunrise-sunset function from solar.el computes sunrise and sunset. I would also like to have a function that computes the end/beginning of

  1. civil twilight (center of sun 6 deg below horizon)
  2. nautical twilight (center of sun 12 deg below horizon)
  3. astronomical twilight (center of sun 18 deg below horizon)

Does anyone know of elisp-code (or a package) for computing said times?

Edit: There seem to be a solution within solar.el: The function solar-sunrise-sunset calls the function solar-sunrise-and-sunset with a HEIGHT of -0.61 degrees (half the apparent diameter of the sun). Using a HEIGHT of -6 degrees should give the end/beginning of civil twilight, and similar for the other.


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