Example of the flux error resulting from our approximation for the transit duration in an eccentric (e = 0.2) circumstellar orbit. We assume a worst-case orientation of periastron and a Jupiter-sized planet to exaggerate the error. The error was computed as the difference between two light curves computed with the batman package. One light curve was initially simulated as a circular orbit and then stretched with a factor of as per Eq. (11). The other light curve was computed with e = 0.2 and using a computationally much more demanding Kepler solver for the orbital motion of the planet.