The Museum of Applied Arts and Sciences (MAAS) Conservation Department has recently completed the restoration of our very old and internationally significant Astrographic (photographic) Telescope. It will be on display in the new dome at the Sydney Observatory soon in early 2015. The telescope was made in 1887 by Howard Grubb, one of the best known instrument makers of the nineteenth century.
In the 1870s Melbourne Observatory worked with South Africa and Madras to undertake a project to measure the positions of 50,000 stars. Each star was measured in real time as it passed through the field of a Transit Circle telescope. With the invention of dry plate photography in the 1870s, astronomers were able to identify stars on photographs that weren’t visible through a telescope and record thousands of stars at once. The idea of photographing and mapping the stars became a possibility.
As a result of the 1887 International Astrographic Congress in Paris, one of the largest scientific projects of the 19th century was undertaken. The Astrographic Catalogue and the Carte du Ciel (Map of the Sky) were two separate but connected initiatives of a massive, international, astronomical project. The intention was to catalogue and map the position of millions of stars from both hemispheres. It involved over 20 Observatories from around the world.
The Observatories in Melbourne, Sydney and Perth were all involved and each was allocated a zone of the sky to record the stars using instruments of a standard pattern. The Carte du Ciel project never came to fruition because the charts proved to be very expensive to reproduce, generally using engraved copper plates (photogravure).
The Astrographic Catalogue project began in 1890 and was meant to take 10-15 years to complete. Most of the photography was done by the 1920s although some photography continued until the 1940s. The massive task of collating and cataloguing was finally completed in 1971. It was expensive to operate and incredibly time consuming as the plate reading was measured by eye and recorded by hand.
This was done with semi-skilled labour, mostly women, who were known as ‘computers’ that filled the data into ‘Ladies logs’. They would manually measure each star in relation to a grid, or reseau (a network of fine lines on a glass plate), that was overexposed onto the plate. Each star’s latitude and longitude position in the sky was found by comparison to a set of reference stars on each plate.
The project was largely ignored for decades because of the difficulty in converting printed data into more useful celestial latidtude and longitude. Between 1987-94, the printed catalogues were transferred into a machine-readable form at the Sternberg Astronomical Institute in Moscow. The century-old star positions were compared to positions found with the Hipparcos space astrometry satellite to measure the tiny but inexorable movements of the stars. These ‘proper motions’ form part of the Tycho-@ Catalogue, which is one of the largest, most accurate star catalogues in the world.
The Astrograph was originally housed at the Melbourne Observatory in 1890. The telescope took over a thousand glass plate negative photographs for the Astrographic Catalogue project from 1890 until 1904. Melbourne Observatory produced three volumes of the Astrographic Catalogue. When Melbourne Observatory closed in 1944, the telescope was re-housed in a purpose-built dome at Sydney Observatory. The project continued for another twenty years under the guidance of NSW Government Astronomer, Harley Wood who completed the remaining five volumes of the Melbourne zone. Many more photographs were taken by Sydney Observatory because its zone contains a large section of the star-rich Milky Way. Fifty three volumes of the catalogue were produced by Sydney Observatory.
Sydney Observatory is currently undertaking a project to conserve the twenty thousand glass plate negatives from its collection. Many of the negatives are from the Astrographic Catalogue project. The Conservation department is currently supervising the project which involves surface cleaning and rehousing the collection.
The telescope was further improved in 1955 when a new tube and camera lens was attached to the Astrograph. The camera lens was made by Taylor, Taylor and Hobson.This produced photographs with a greater field of view and was used to make the Sydney Southern Star Catalogue.
After the project ended, the telescope was transferred to Macquarie University in 1986, along with the original Grubb lens and the Taylor, Taylor and Hobson camera. The university intended to display the telescope in their own Observatory and they began to restore the components in the 1980s. Well known photographer, Max Dupain had previously photographed the telescope in the Sydney Observatory dome and this was used on the cover of the October 1960 edition of the Reader’s Digest. In the photograph, the telescope looks blue but the colours have been tweaked in the development process. In actual fact, the colour of the telescope, from 1944, was khaki.
However, restoration enthusiasts from Macquarie University chose to paint the components of the telescope blue, referring to Max Dupain’s incorrect photograph. The eye piece and brass work on the telescope were fully restored but due to resourcing issues, the restoration project never came to fruition at the university, so the telescope was returned, in pieces, to the MAAS in 2009. Another telescope, the Hoskins,also painted blue, was returned to us at the same time, with the smaller components from both telescopes packed in boxes together. There were 9 pallets of parts to sort out and reassemble.
Written by Kate Chidlow, Conservator