Assembly of the base box

An important part of the telescope is the base box which forms a platform on which the main structure of the telescope is attached.

The base box for the Liverpool Telescope

The base box is fabricated from steel plates that are carefully welded together. It is very important that the base box is manufactured to a high degree of accuracy so that the telescope fits together perfectly.

Most of the parts that make up the telescope are designed by Telescope Technologies Limited (TTL) using 'state of the art' computer aided design (CAD) software. The design is then given to a specialist manufacturer who makes the part. Some parts are only small but others, such as the base box, are very large weighing many tonnes.

A bearing being fitted to the base box

Before the base box can be placed on the azimuth ring special hydrostatic bearings must be fixed to the under side of the base box. You can see one of these bearings being attached in the photograph.

Accuracy in design of each part of the telescope is most important, for example, the hydrostatic bearing must fit perfectly to the base box even though each part is made by a different manufacturer.

What exactly is a hydrostatic bearing?

It is very important that the telescope can follow the movement of the stars across the night sky in a very smooth way. This is not an easy task especially when the instrument weighs 24 tonnes. The hydrostatic bearings are specially designed to cope with the weight of the telescope and at the same time provide very smooth movement. The telescope must not in any way judder as it moves because this will result in very poor image data from the telescope.

In these bearing oil is forced (pumped) between two smooth metal surfaces causing them to separate. This separation is about 70 microns or 70 millionths of a metre. To give you an idea of the size of this gap a human hair is approximately 30 microns.

With the metal surfaces separated in this way very smooth movements of the bearing are achieved.

The base box fitted to the azimuth ring

The next step in assembly of the telescope is to position the base box and hydrostatic bearings onto the azimuth ring.

This is a very delicate job that requires considerable care and absolute precision.

The top photograph to the left shows the base box with the hydrostatic bearings located on the azimuth ring. Note the oil tray around the outside of the azimuth ring to collect the oil as it flows from the bearings, it is then re-cycled back to the hydrostatic bearings.

In the second photograph you can see oil in the oil tray and the azimuth ring shining with a thin film of oil over its surface.