CONAN.utils.CA_08_PCmodel

CONAN.utils.CA_08_PCmodel#

CONAN.utils.CA_08_PCmodel(phi, Fd, C1, D1, C2, D2)#

Calculate the phase curve of a planet using the Cowan & Agol 2008 model. See also https://iopscience.iop.org/article/10.3847/1538-3881/ae0e52/meta and https://arxiv.org/pdf/2305.06240

The equation is given as F = Fd + C1*(cos(theta) - 1) + D1*sin(theta) + C2*(cos(2*theta) - 1) + D2*sin(2*theta) where theta = phi + pi, and phi is the phase angle of the planet (true anomaly+omega-pi/2) in radians.

Parameters:

  • phi (array-like) – phase angle (2*pi*phase for circular orbit) or true anomaly+omega-pi/2 in radians.

  • Fd (float) – Dayside flux/occultation depth

  • C1 (float) – first cosine coefficient

  • D1 (float) – first sine coefficient

  • C2 (float) – second cosine coefficient

  • D2 (float) – second sine coefficient

Returns:

F – planetary flux as a function of phase angle

Return type:

array-like

Example

>>> from utils import CA_08_PCmodel
>>> import numpy as np
>>> phases = np.linspace(-0.25, 0.75, 10000)
>>> phi = 2 * np.pi * phases
>>> Fn, Fd = 50e-6, 400e-6
>>> C1 = (Fd - Fn)/2
>>> D1, C2, D2 = -139e-6, 46e-6, -15e-6  #D1 somehow influences the phase shift. find an expression for it
>>> res = CA_08_PCmodel(phi, Fd, C1, D1, C2, D2)

>>> from CONAN.utils import cosine_atm_variation
>>> pc = CA_08_PCmodel(phi, Fd, C1, D1, C2, D2)
>>> cos = cosine_atm_variation(phi, Fd, Fn,delta).pc
>>> plt.figure()
>>> plt.plot(phases, pc)
>>> plt.plot(phases, cos)
>>> plt.axvline(0.5, color='k', ls='--')
>>> # plt.axvline(0.5 - np.radians(delta) / (2 * np.pi))
>>> plt.axhline(Fd-2*C1, color='k', ls='--')
>>> plt.axvline(0)
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