Mary Greayer's valued work tracks hundreds of stars as observer/ computer at Adelaide Observatory 1890-98
Mary Greayer with South Australian government astronomer Charles Todd and his assistant William Cooke in 1895. At right: The Thomas Cooke and Sons Equatorial telescope used by Greayer at Adelaide Observatory.
Images courtesy Perth Observatory and Museums Victoria
Mary Emma Greayer, employed at Adelaide Observatory on West Terrace from 1890, made major contributions to measuring and computing the position of stars for the Astrographic Catalogue.
Greayer’s work, with other women* in Australian colonies’ observatories, has been overlooked but famous South Australian government astronomer Charles Todd praised her as “a veritable Caroline Herschel”. (Carline Herschel was hard-working astronomer partner and sister of William, famous for discovering the planet Uranus and its two moons.)
Todd noted that Adelaide Observatory’s work of measuring standard stars for the Astrographic Catalogue stalled when Greayer had to leave, after marrying assistant government astronomer Richard Griffiths in 1898.
Before working at Adelaide Observatory, Greayer was an a temporary assistant at Gepps Cross and then Angaston public school in 1886. Because Greayer wasn’t a permanent observatory staff member, her name doesn’t appear in official records, but time book and log books showed the extent of her work, included observing through and calibrating telescopes. Greayer worked on three or more nights per week with assistant astronomer William Ernest Cooke (who married her sister Jessie Greayer in 1887) from 1891 and, when Cooke resigned in 1896, with future husband Richard Griffiths.
The 1893 logbook lists Greayer as the main observer of individual zenith stars. (She took micrometer readings and reduced the nadirs.) Diary notes indicate she adjusted the 6-inch Troughton and Sims Transit Circle telescope and calibrated other instruments. This work is in six volumes and each volume holds details of about 990 stars. Greayer observed and reduced many hundreds of clock stars with the transit instrument.
At night, Greayer observed more than one third of the positional stars for the Melbourne Astrographic Catalogue zone in 1894-98, using the 8-inch equatorial telescope. During the day in 1895-97, Greayer reduced the Melbourne Astrographic Zone stars (−65° to the South Pole) from apparent to mean RA (right ascension) and NPD (North Pole distance).
While Greayer didn’t develop astronomical theories, her work was essential to producing star catalogues and identifying double stars and comet locations – work described by 19th Century astronomer Dorothea Klumpke as “truly scientific”.
Greayer's interest in astronomy and curiosity about new developments led her in 1893 to be one of the first three women – with Lorna and Alice Maud Todd – to join the Astronomical Society of South Australia, one of the world’s first astronomical societies to enrol women as members without prejudice.
