transit

tayph.transit(dp, p=[])

This code uses Ians astro python routines for the approximate Mandel & Agol transit lightcurve to produce the predicted transit lightcurve for the planet described by the configfile located at dp/config. This all assumes a circular orbit. =========== Derivation: =========== occultnonlin_small(z,p, cn) is the algorithm of the Mandel&Agol derivation. z = d/R_star, where d is the distance of the planet center to the LOS to the center of the star. sin(alpha) = d/a, with a the orbital distance (semi-major axis). so sin(alpha)*a/Rstar = d/a*a/Rstar = d/Rstar = z. a/Rstar happens to be a quantity that is well known from the transit light- curve. So z = sin(2pi phase)*a/Rstar. But this is in the limit of i = 90.

From Cegla 2016 it follows that z = sqrt(xp^2 + yp^2). These are given as xp = a/Rstar sin(2pi phase) and yp = -a/Rstar * cos(2pi phase) * cos(i).

The second quantity, p, is Rp/Rstar, also well known from the transit light- curve.

cn is a four-element vector with the nonlinear limb darkening coefficients. If a shorter sequence is entered, the later values will be set to zero. By default I made it zero; i.e. the injected model does not take into account limb-darkening.