CONAN.utils.lambertian_atm_variation
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.. py:function:: CONAN.utils.lambertian_atm_variation(phi, Fd=0, Fn=0, delta_deg=0, inc_rad=np.pi / 2, night_phase_var=False)

   Calculate the phase curve of a planet approximated by a lambertian function.
   Eq. 3 of Esteves+2013 (https://iopscience.iop.org/article/10.1088/0004-637X/772/1/51) is used to calculate the flux variation.


   :param phi: phase angle (2*pi*phase for circular orbit) or true anomaly+omega-pi/2 in radians.
   :type phi: array-like
   :param Fd: Dayside flux/occultation depth
   :type Fd: float
   :param Fn: night side flux
   :type Fn: float
   :param delta_deg: hotspot offset in degrees.
   :type delta_deg: float

   :returns: **F** -- planetary flux as a function of phase
   :rtype: array-like