Thornton Telescope refurbishment project (1985–1989)

After the first ten years, the Thornton telescope was completely stripped down (down to individual washers!) cleaned, treated, and put back together. A major enhancement was that a azimuth adjustment was added, so that the polar axis could be better aligned. [This alignment was carried out after the refurbishment, largely by St John Robinson.]

This doesn't sound so significant, until you realise the telesope weighs a couple of tons! Taking it apart was no trivial feat. And putting it back together was equally challenging!


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James and Steve in early disassembly work (October 1984) After the mirror cell had been removed After the declination axis had been removed
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Winching out the polar axis Some of the bearings Simon using a needle gun to remove rust


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Paul mixing concrete for the new fitting Fixing bolts to hold base frame Base frame fitted (note the bolts for the azimuth adjustment at the bottom of this picture)
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The main frame fitted on the base frame The polar shaft fitted to frame Polar axis fitted in shaft
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Top box and declination counterweight fitted The central box is very heavy But it was fitted; note the yoke on the left (the telescope is very out-of-balance)
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Top box and declination counterweight fitted The main gear wheel (certified better than 1 arc-second error by National Physics Lab); here it is being cleaned Measuring the runout of the gear with a dial gauge
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Beginning to look like a telescope (but upside down) Looking complete With the 'sock' that Steve made to keep the tube light-tight

The telescopes after the refurbishment (seen in the 1990s)

One advance was that the old paint scheme was replaced by one with more visual impact, partly for safety reasons (avoiding banging into the telescope in dim light). It was finished in Nanking Blue (static parts) and Tangerine (moving parts).

Grubb and Hindle telescopes Thornton telescope
Some of the details of the Grubb refractor were also finished in orange The Thornton in its new colour scheme

Several other pieces of work were carried out at the same time, including remounting the aerial camera, and painting the binoculars. After the work had been finished, there was a Star Party to celebrate.