Telescope Making > ATM Diaries 2
Both 20 inch scopes are complete! by Johann Swanepoel - November 2010
Both 20 inch scopes are complete!
One of them I built for my friend in Gauteng which was also complete last April just before ScopeX 2010. I could only transport one of them in my bakkie to ScopeX.
The two 20 inch mirrors have been aluminised at last! What a relief.
I went to SAAO in Sutherland and both mirrors were done at the same time in the aluminising chamber/tank of the 40 inch Elizabeth telescope. After arrival, the mirrors were extensively washed, cleaned and dried and then mounted in the lid of the tank using special brackets that could hold the mirrors side-by-side in a vertical position. Evacuation started later the afternoon and continued overnight until 12:00 the next day. The evaporation/deposition process was then activated - this lasted just a couple of minutes. The tank was then opened to reveal the shiny beauties. See attached.
The mirrors were transported in special boxes I had made for transporting and storing the mirrors. The boxes are made from generally available shutterply and other hardware items. I could have used marine ply but that would be overdoing it. Each mirror has its own box. The polystyrene sheet at the bottom of the box has two holes cut to allow one's hands to enter below the mirror in order to lift it out safely without touching the surface. Nothing comes into contact with the surface.
My friend in Gauteng will need to come and pick up his 2o" scope soon - I need the space in my garage!