Phase curve of a circular orbit around the secondary eclipse showing the difference flux reference levels. The duration of the secondary eclipse is equal to the transit duration. The times t₁, t₂, t₃, and t₄ define the ingress and egress moments of the planetary occultation in the same way as T₁, T₂, T₃, T₄ for the primary transit. The eclipse depth is actually the difference between the flux references of planet’s brightness at t₁ ∕t₄ and the stellar brightness at t₂∕t₃.