The discovery of subgaint stars opened the field of observational stellar evolution. Alan Sandage (Carnegie Institution) teamed up with Steven Majewski (University of Virginia), and Majewski’s student, Rachael Beaton (now a postdoc at Carnegie Institution) to delve into the history of the discovery of subgiant stars. They showed that the observations of the subgiants discovered at the Mount Wilson Observatory in 1935 were remarkably accurate.