Geometric albedo as a function of the planet day-side brightness temperature from Eq. (3). The vertical lines correspond to the extreme values for a planet that absorbs all the incoming flux: ε = 0 when all the energy received on the day side is reemitted; ε = 1 when all the energy received on the day side is fully re-distributed.The gray band indicates the albedo values allowed by the 1σ uncertainty on the occultation depth, which is assumed to be the dominant one.