SALT - Southern African Large Telescope

Dome

General

The Dome is a 25-meter diameter half-sphere dome with a shutter opening of 11 meters. The rotating mass is about 30 Tons. The dome insulated to help achieve the thermal specification of the telescope and have 4 dome drives for rotation.

The main purpose of the Dome is to:

  • Provide protection to the elements (wind, precipitation, lightning).
  • Provide a shutter opening through which observing can be done - without disturbing seeing- and which can be closed (repeatable, weather tight seal) during daytime.
  • Align the shutter with the structure of the telescope during observations or alignment of primary mirror.
  • Provide thermal insulation in accordance with the installed air-conditioning system.
  • Provide a 1-Ton lifting crane, with the specified reach, that can move in three axes (dome rotation being one of them).

The Dome can be broken down into two separate sub-systems, the dome shell assembly and the drives and controls that were contracted separately.

Dome Shell Assembly

This forms the half sphere structure (support and cladding) with the shutter opening and shutter to cover the opening. It includes all insulation to meet the air-conditioning requirements, the dome crane, the slip ring (to take power and signal lines to the shutter, dome crane and lights) and lightning protection, which interfaces to the facility at the dome ring.

The Dome Shell Assembly Contract was awarded to BKS Advantech, who teamed up with Starnet (USA). The design is currently being done - installation of the dome will be completed by July 2002.

 


Nice Geodesic Dome Image


Dome as at HET

Drives and Controls

The drives and controls consist of the dome drives and bogie assemblies (mounted on top of the ring wall I-beams), the shutter drives and the controls for the above. There are 4 dome drives to allow for good distribution of drive loads and an additional 12 bogies (16 in total) that provide support for the dome. The bogies have been designed to take up out-of-roundness and out-of-flatness of the dome ring, while maintaining a well-distributed load over the 16 support points.

The supplier for the controls on the dome is Reutech Radar Systems. The CDR has been completed and manufacturing will commence soon.


Bogie Assembly


Dome Drive