Who’s the fairest mirror segment of them all?

ESO engineers, technicians and contractors stand around one of the Extremely Large Telescope (ELT)’s primary mirror segments. They are not inspecting their own reflections — they are, in fact, checking the quality of the coating they just applied to the segment. The coating consists of a highly reflective 1.7g silver layer and additional adhesion and protection layers. One of the two chambers used for the coating process can be seen in the background.