Third VLT 8.2-m Mirror Successfully Coated and Installed at MELIPAL
3 December 1999
In the course of the current installation of ESO's Very Large Telescope (VLT) , a delicate operation has just been successfully achieved at the Paranal Observatory. The coated 8.2-m Zerodur main mirror for the third VLT 8.2-m Unit Telescope, MELIPAL , is now in place!
Following removal from its transport box and insertion into the Coating Chamber, the third 8.2-m, 22-tonnes Zerodur mirror was coated with a thin layer of highly reflecting aluminium in the morning of Monday, November 29. An inspection of the fresh coating on the 50+ m 2 surface area was carried out immediately thereafter and indicated that this difficult operation was a perfect success. The measured reflectivity was 92 percent - this is an excellent value.
The enormous mirror was then lifted out of the chamber and carefully lowered onto the 150 computer-controlled supports in its mirror cell.
In the afternoon of Thursday, December 2, the cell with the mirror was transported to the MELIPAL enclosure and placed under the telescope.
The M3 tower with the elliptically shaped, flat M3 mirror was installed at the hole at the centre of the main mirror. This morning, the complete assembly was lifted and bolted to the back of the MELIPAL mechanical structure.
Comprehensive adjustment and tests will now take place. "First Light" for MELIPAL is expected in just over two months. A few months later, the VIsible MultiObject Spectrograph (VIMOS) will be installed at one of the Nasmyth foci.
As they are no longer needed at MELIPAL , the Lift Platform and Carriage are being moved over to YEPUN (UT4) to be ready for the M1 Cell installation there that starts in early January 2000.
The following digital photos were obtained during the past days and illustrate the above described operation.