AP are taking direct orders for their 3600 GTO "el Capitan" mount if any one needs a "conservative" 300lbs load capacity excluding counter weights. Add the high precision encoder to your order and get 0.5arcsecs peak to peak tracking accuracy without PEC !!!! It would cost $19900 US ($20080 AU) which is a bit but not as much as the crane you will have to buy to put it together or move it around
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Mark