VLT´s UT2 coating

Paranal engineers carefully follow the first step of the UT2 recoating process, when the primary mirror (M1) cell is detached from the telescope structure. The whole cell weights 45 tonnes and leans on a special crane which takes it out of the telescope building. 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.