Timur's grandson, who governed Samarkand but was far more interested in the sky. He built an observatory with a sextant sunk into bedrock and measured the stars for two decades.
Key achievements
Compiled the Zij-i Sultani star catalogue of over a thousand stars in 1437
Calculated the length of the sidereal year to within about a minute of the modern value
Built the Samarkand observatory, whose sextant arc still survives