Since its completion in January 2015, the LSST M1M3 mirror has been in storage in Tucson awaiting completion of the mirror cell. When the cell is complete, it will be joined to the M1M3 mirror for additional testing at the University of Arizona’s Richard F. Caris Mirror Lab. The two pieces will ship separately to Chile and then be reunited for the duration of the LSST ten-year survey from Cerro Pachon.
This image shows the continuing progress at CAID Industries on the fabrication and assembly of the mirror cell weldment. Here is the vacuum boundary vessel as viewed from the rear (note the rear access door). It is undergoing helium leak testing of the welded joints to confirm the connections are fused to hold a proper vacuum during mirror coating operations. The mirror cell is scheduled for completion in mid-2016.