astroforge.coordinates.nutate#

astroforge.coordinates.nutate(mjd)[source]#

Compute the nutation of the Earth’s rotational axis at the time given.

The first two outputs are the nutation angles in longitude and obliquity: \(\Delta\psi\), \(\Delta\epsilon\).

The third output is the true obliquity at the time given: \(\epsilon' = \epsilon + \Delta\epsilon\)

The final output is the total nutation matrix.

Parameters:

mjd (float)
Modified (Time at which nutation is computed. Time is specified as a)
system. (Julian Date (MJD) in the UT1 time)

Returns:

dpsi (float) – Nutation in longitude (radians); \(\Delta\psi\)
deps (float) – Nutation in obliquity (radians); \(\Delta\epsilon\)
true_obliquity (float) – True obliquity of the ecliptic (radians); \(\epsilon'\)
nutation_matrix (NDArray[np.float64]) – Rotation matrix

References

Examples

>>> dpsi, deps, true_oblq, R = nutate(59025.0)
>>> print(dpsi, deps, true_oblq)
-8.137262475393194e-05 -1.4786332984509557e-06 0.4090446167405599

>>> with np.printoptions(suppress=True):
        print(R)
[[ 1.          0.00007466  0.00003236]
[-0.00007466  1.          0.00000148]
[-0.00003236 -0.00000148  1.        ]]

astroforge.coordinates.nutate#

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