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sites.astro.caltech.edu
grOEy
TIL The Hale telescope features a 200 inch (5.08m) diameter mirror. The mirror took 10 months anneal and was delivered to Caltech in 1936. The telescope was completed in 1948 as it took years of grinding and polishing to make the mirror accurate to 2/1,000,000ths of an inch of a perfect paraboloid.