HarmonicaTransit

class harmonica.HarmonicaTransit(times=None, pnl_c=20, pnl_e=50)

Bases: object

Harmonica transit class.

Compute transit light curves for a given transmission string through parameterising the planet shape as a Fourier series.

Parameters:

• times (ndarray, optional) – 1D array of model evaluation times [days].

• pnl_e (pnl_c and) – Number of legendre roots used to approximate the integrals with no closed form solution. pnl_c corresponds to when the planet lies entirely inside the stellar disc, and pnl_e corresponds to when the planet intersects the stellar limb. Allowed values = {10, 20, 100, 200, 500}. Use get_precision_estimate() to check model precision.

Notes

The algorithm is detailed in Grant and Wakeford 2023.

set_orbit(t0=None, period=None, a=None, inc=None, ecc=0.0, omega=0.0)

Set/update orbital parameters.

Parameters:

• t0 (float) – Time of transit [days].

• period (float) – Orbital period [days].

• a (float) – Semi-major axis [stellar radii].

• inc (float) – Orbital inclination [radians].

• ecc (float, optional) – Eccentricity [], 0 <= ecc < 1. Default=0.

• omega (float, optional) – Argument of periastron [radians]. Default=0.

set_stellar_limb_darkening(u=None, limb_dark_law='quadratic')

Set/update stellar limb darkening parameters.

Parameters:

• u (ndarray) – 1D array of limb-darkening coefficients which correspond to the limb-darkening law specified by limb_dark_law. The quadratic law requires two coefficients and the non-linear law requires four coefficients.

• limb_dark_law (string, optional; quadratic or non-linear) – The stellar limb darkening law. Default=`quadratic`.

set_planet_transmission_string(r=None)

Set/update planet transmission string parameters.

Parameters:

r (ndarray (N,) or (M, N)) –

Transmission string coefficients. 1D array of N Fourier coefficients that specify the planet radius as a function of angle in the sky-plane.

\[r_{\rm{p}}(\theta) = \sum_{n=0}^N a_n \cos{(n \theta)} + \sum_{n=1}^N b_n \sin{(n \theta)}\]

The input array is given as r=[a_0, a_1, b_1, a_2, b_2,..]. For time-dependent transmission strings, use a 2D array with M time steps and N Fourier coefficients, where M is equal to the number of model evaluation times.

get_transit_light_curve()

Get transit light curve.

Returns:

fluxes – The transit light curve fluxes evaluated at M times.

Return type:

ndarray (M,)

get_planet_transmission_string(theta)

Get transmission string evaluated at an array of angles

around the planet’s terminator.

Parameters:

theta (ndarray,) – 1D array of angles at which to evaluate the transmission string.

Returns:

• if r.ndim == 1 –

  r_pndarray (N,)

  The transmission string, \(r_{\rm{p}}(\theta)\), evaluated at N thetas.

• elif r.ndim == 2 –

  r_pndarray (M, N)

  The transmission strings, \(r_{\rm{p}}(\theta)\), each M strings evaluated at N provided thetas.

get_precision_estimate()

Get light curve precision estimate.

Returns:

residuals – Difference between light curve generated at user set precision and the light curve at max precision.

Return type:

ndarray