Mary Ross Calvert was born on June 20, 1884, in Nashville, Tennessee, to Alice Rosamond and Ebenezer Calvert. She was the eldest of four daughters. Her father’s elder sister Rhoda was married the astronomer Edward Emerson Barnard.
Her father and his younger brother Peter Ross Calvert ran Calvert Bros. Photography Studio, above the United Cigar Store at the southeast corner of 4th and Union Streets in Nashville. The studio had been founded by J. H. Van Stavoren; Rodney Poole bought it at a chancery court sale in 1871, and the Calvert brothers bought it from Poole in 1896.
In 1905, Mary Calvert started working at Yerkes Observatory, Wisconsin as assistant and computer for her uncle, Edward Bernard, who was also professor of astronomy at the University of Chicago. She stayed at her uncle’s house whilst employed by him. He was known for his discovery of the high proper motion of Barnard’s Star.
In 1923, when Edward Barnard died, Mary became curator of the Yerkes photographic plate collection and a high-level assistant, until her retirement in 1946.
Barnard’s work A Photographic Atlas of Selected Regions of the Milky Way was completed after his death in 1923 by Edwin B. Frost, director of the Yerkes Observatory, and Calvert. The work was nominally his although Calvert had done the preliminary work under his supervision, but it was she who did the computations necessary to complete the tables, numbered and sketched in darker objects added annotation to the reference stars.
Calvert and Frost decided that it should be published in two volumes. The atlas contained 349 dark objects although later editions covered 352 as three had been omitted by mistake. There were several more dark objects that were on the plates but that were not catalogued possibly due to Barnard’s death, as both Calvert and Barnard had been aware of them.
Only 700 copies were printed in 1927, making the original edition a collector’s item. The Astronomy Compendium calls it a “seminal work”.
In 1934 she and Frank Elmore Ross published a photographic study, Atlas of the Northern Milky Way, based on Ross’s photographs.
Later life & death
After Mary Calvert retired from Yerkes in 1946, without receiving a pension, she returned to Nashville where she worked in her sister’s photographic studio part-time.
She died five days after her 90th birthday in Nashville in 1974.
- A Photographic Atlas of Selected Regions of the Milky Way (with Edward Barnard and Edwin Frost) (1927)
- Atlas of the Northern Milky Way (with Frank Elmore Ross), University of Chicago Press (1934)