Gemini South Primary mirror reflectivity plot

The reflectivity requirements are plotted in red. The newly-measured values at four wavelengths on the primary mirror itself (blue circles) exceed these requirements. A further comparison comes from a small sample that receives the same coating along with M1 and that can be measured from ultraviolet to near-infrared wavelengths. The reflectivity of this sample is plotted as a continuous line. Read more here.