Stonyhurst disks
Encyclopedia
A Stonyhurst disk is a transparent circular grid with lines of longitude and latitude that which can overlay a solar image to reference the positions of sunspots. This overlay system was originally created at the Stonyhurst College observatory
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Stonyhurst Observatory
The Stonyhurst Observatory is a functioning observatory and weather station at Stonyhurst College in Lancashire, England. Built in 1866, it replaced a nearby earlier building, built in 1838, which is now used as the Typographia Collegii....
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