meepmeep.numba2d.sep

meepmeep.numba2d.sep(time: float | ndarray[tuple[Any, ...], dtype[_ScalarT]], tc: float, p: float, c: ndarray[tuple[Any, ...], dtype[_ScalarT]], te: float = 0.0) → float | ndarray[tuple[Any, ...], dtype[_ScalarT]]

Evaluate the projected planet-star separation at an absolute time.

Computes the sky-plane (x, y) position and returns the Euclidean distance sqrt(x^2 + y^2). This is the quantity most commonly used by transit light-curve models, where it represents the center-to-center separation between the planet and star projected onto the plane of the sky.

Accepts a scalar time or a 1-D array of times and dispatches to the appropriate kernel at compile time (inside @njit) or at call time (pure Python).

Parameters:

timefloat or NDArray

Absolute observation time(s).

tcfloat

Transit-centre time (time of inferior conjunction), on the same time axis as time.

pfloat

Orbital period.

cNDArray

A (2, 5) coefficient matrix produced by solve2d.

tefloat, optional

Expansion-point offset from the transit centre [days] - the same value that was passed to solve2d. Defaults to 0.0, the expansion point at the transit centre.

Returns:

dfloat or NDArray

Projected planet-star center distance in units of stellar radii. Always non-negative; the sign of the line-of-sight depth (transit vs. eclipse) is not encoded here.