Nutze Skyfield fuer praezisere Daemmerungsberechnung

public/py/vendor/skyfield/tests/test_earthlib.py

@@ -0,0 +1,14 @@
+from numpy import array, isnan, nan, sqrt
+from skyfield.earthlib import AU_M, ERAD, refract, reverse_terra, tau
+
+def test_reverse_terra_with_zero_iterations():
+    # With zero iterations, should return "geocentric" rather than
+    # "geodetic" (="correct") longitude and latitude.
+    lat, lon, elevation_m = reverse_terra(array([1, 0, 1]), 0, iterations=0)
+    one_millimeter = 1e-3
+    assert abs(lat - tau / 8) < 1e-16
+    assert lon == 0.0
+    assert abs(elevation_m - (AU_M * sqrt(2) - ERAD)) < one_millimeter
+
+def test_refract_with_nan_does_not_loop_forever():
+    assert isnan(refract(nan, 10.0, 1010.0))