VLT´s UT2 coating

The primary mirror (M1) cell of UT2 is detached from the telescope structure for coating. The whole cell weights 45 tonnes and leans on a special crane which takes it out of the telescope building. The engineers tighten the blue tapes which will support the cover of the mirror during its transportations from the telescope to the Main Maintenance Building (MMB). The cleaning of the VLT´s M1s is a very delicate operation which takes place every 18 months and consists in removing the reflective aluminum layer by chemical washing and then recoating the mirror.