At which observatory did Edwin Hubble do his University of Chicago graduate work?

Edwin Hubble did his University of Chicago graduate work at Yerkes Observatory.

After about a year teaching at New Albany High School, Hubble returned to the University of Chicago in 1914 to pursue graduate astronomy. His work was carried out at the university’s Yerkes Observatory in Williams Bay, Wisconsin, then one of the leading astronomical research centers in the United States. Edwin Brant Frost supervised his studies.

Yerkes gave Hubble access to major instruments, including its famous 40-inch refracting telescope. His graduate research focused on faint nebulae, objects that astronomers were still trying to classify and understand. He completed his doctorate in 1917; accounts differ in how they summarize the timing of the degree and his subsequent wartime service, but Yerkes is the key location associated with his graduate research.

The other options are observatories associated with important astronomical work, but not with Hubble’s University of Chicago graduate training. Hubble later moved to Mount Wilson Observatory, where observations with larger telescopes helped transform debates about galaxies and the scale of the universe.