Left panel. Top: phase-folded transit of Kepler-39b along with the transit models for the circular (red solid line) and eccentric (red dotted line) orbits. The two models are indistinguishable. Middle: residuals of the circular orbit. Bottom: residuals of the eccentric orbit. Right panel. Top: phase-folded radial-velocity curve of Kepler-39 and, superimposed, the Keplerian models for the circular (red solid line) and eccentric (red dotted line) orbits. Middle: O–C of the circular orbit. Bottom: O–C of the eccentric orbit.