Stewart Sharpless

Stewart Sharpless (March 29, 1926 – January 19, 2013)^[1] was an American astronomer who carried out fundamental work on the structure of the Milky Way galaxy.

As a graduate student at Yerkes Observatory he worked under William Morgan with fellow graduate student Don Osterbrock.^[2] He helped Harold Johnson and Morgan with calculations used to help define the UBV photometric system.^[3] In 1952, Sharpless and Osterbrock published their observations that demonstrated the spiral structure of the Milky Way by estimating the distances to H II regions and young hot stars. ^[4] For a while Sharpless was at Mount Wilson Observatory where he worked on galaxy photography with Walter Baade and Edwin Hubble.^[5]

In 1953 Sharpless joined the staff of the United States Naval Observatory Flagstaff Station.^[5] Here he surveyed and cataloged H II regions of the Milky Way Galaxy using the images from the Palomar Sky Survey. From this work Sharpless published his catalog of H II regions in two editions, the first in 1953 with 142 nebula.^[6] The second and final edition was published in 1959 with 313 nebulae^[7] (see Sharpless catalog).

Stewart Sharpless was before his death a retired Professor Emeritus in the Department of Physics and Astronomy at the University of Rochester.