Who was an astronomer who helped survey the land where Washington D.C.was built?

The astronomer who helped survey the land for Washington, D.C., was Andrew Ellicott. He was appointed by President George Washington to conduct the survey of the district in 1791. Ellicott worked alongside Pierre L'Enfant, the city's planner, and utilized his expertise in astronomy to establish the geographical layout of the new capital. His work was crucial in determining the boundaries and orientation of the city.