Rubin Observatory’s 8.4-meter combined primary/tertiary mirror was coated with protected silver in April 2024. The reflective coating was applied using the observatory’s onsite coating chamber, which will also be used to re-coat the mirror as necessary during Rubin’s 10-year Legacy Survey of Space and Time. In this image, the mirror is lying flat in the foreground, and is reflecting the coating chamber (the silver object behind the mirror) and the ceiling of the observatory.