Eccentricity for planet about pandora HOT 3 CLOSED

Not easy to change in current coordinate system
Computationaly costly - 10x--100x?

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Easy to implement, if planet velocity constant during transit duration. Acceptable simplification in most cases?

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The planet velocity has a radial and a tangential component with respect to the star. During mid-transit, these components are virtually identical (modulo the algebraic sign) to the radial and tangential components with respect to our line of sight. I suspect that only the tangential component is relevant to the shape of the transit light curve. So if "planet velocity" in your comment refers to the tangential velocity component, then the assumption of constant in-transit velocity for the planet is most plausible

• for small eccentricities
• if the transit occurs near apoastron

(see Eq. 4 for dΘ²/dt² at https://en.wikipedia.org/wiki/Kepler_orbit). In turn, the higher the eccentricity and the closer the transit occurs to the periastron, the less practical the approximation.

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