[From Mount Stromlo] the stars shine with a steady light upon an inky-black background.

Pietro Baracchi, Government Astronomer of Victoria, 1913

Searching for a site

In 1909, the Australian Government gave the go-ahead for a solar observatory. Much debate was had about the siting of the first Commonwealth observatory... should an existing state observatory take over the mantel as Commonwealth Solar Observatory? 

Duffield had originally favoured South Australia for the site... but the decision was made to establish a new Commonwealth Solar Observatory in the Federal Capital Territory (now the ACT). Alfred Deakin, then Prime Minister, wrote to Duffield asking:

I shall be glad to receive your memorandum setting out what you consider to be the chief desiderata of the site at your convenience.

1 December 1909 Letter to Duffield from Alfred Deakin, MS09500085. Courtesy of the Academy of Sciences archives

Dr. Duffield did so. He identified eight key 'qualifications' for the perfect observatory site:

1. Low average rainfall - the character of the fall requires consideration - whether due to a small number of heavy showers or spread over a large number of days of light rain
2. Rainfall should prefereably not be monsoonal - observations from an Australian statoin are specially required during the months of December, January and February at whcih time other observatories are working under unfavourable weather conditions.
3. Low average wind velocity - a tower telescope (which is recommended for an Australian station) requires freedom from vibration under ordinary working conditions. The latest form of wind-guards renders them stable in light breezes
4. Equable weather and steady barometer readings over long periods 
5. Large number of sunny days i.e. cloudlessness - continuous clear weather for periods of many weeks is required for continuous observation
6. Transparency of the atmosphere
7. Clearness of the atmosphere - transparency and clearness do not necessarily go together, and except for radiation work the latter is more important 
8. Station should be at good elevation - as a rule the transparency and clearness of the atmosphere increase with evaluation

Excerpt of memorandum sent to Alfred Deakin and Pietro Baracchi regarding 'qualifications' for the new observatory site, 1909, MS09500088. Courtesy of the Academy of Science archives] 

On 1 March 1910, a Board of five men, including Pietro Baracchi, Government Astronomer of Victoria, met at the Commonwealth Survey Camp. Together, they identified and visited five potential locations as the site for the new observatory:

1. Black Moutain
2. Mount Mugga
3. Mount Ainslie
4. the Cotter-Murrumbidgee River junction
5. Mount Stromlo

It was Mount Stromlo that was selected as the test site due to:

its convenient situation, accessibility and moderate but sufficient distance from the Federal City; its favourable orientation relatively to the City and to the prevailing winds; its topographical features affording abundant space at the highest levels; its commanding view, and the possibility of making the site one of the most attractive and picturesque within the Federal Territory. 

From, Canberra Capital City of the Commonwealth of Australia, 1913 report

After the Board had determined on Mount Stromlo, it became a testing site.  On 27 March 1911, Baracchi reports that he has selected a definite site for the temporary observatory atop of the mountain. In June of that year, the site for the observatory and an access road are leased from Frederick Campbell of Yarralumla. The road is completed in September 1911, and the Oddie telescope transported to Canberra for the purpose of testing the site.

For this, they required instruments.

In July 1910, Baracchi was instructed to take delivery of the Oddie telescope. The Oddie telescope was sent from Ballarat to Melbourne Observatory to be reconditioned and a timber dome built before being transported to Mount Stromlo. 

Testing begins...

September 1911 - May 1913. Canberra. Armed with the 'desiderata' specified by Dr. Duffield years earlier, Pietro Baracchi and his assistant, Dr Joseph Baldwin spend a week every 5 to 6 weeks making astronomical and meterological observations of the skies from Mount Stromlo (see Table 1 for schedule of test visits and tasks undertaken).

Table 1

Baracchi took stellar photographs during his visits to Mount Stromlo. Twenty-three of those photographic plates remain in the Museums Victoria collection. They cover Nubecular Major (Large Magellanic Cloud), Star Cluster in Scorpio and Comet Gale. 

 Of Mount Stromlo, Baracchi says,

In clear, calm nights the appearance of the heavens from the zenith to the horizon presents a spectacle exceedingly brilliant. The stars shine with a steady light upon an inky-black ground. The faintest branches of the Milky Way, and other objects which are nearly visible to the naked eye from lower lands in closer vicinity to the sea, appear conspicuous at Mt. Stromlo.

From, Canberra Capital City of the Commonwealth of Australia, 1913 report

 

Stellar photographs were taken using a doublet portrait photographic lens by Dallmeyer (6-inch clear aperture and 47-inch focal length) with Ilford 'special rapid' whole plates. The camera/lens configuration was attached to the telescope via a metallic mounting that was made for it in the workshop of the Melbourne Observatory, 'provided with a specially designed and very carefully made plate carrier, a spring shutter, and fine adjustments for collimation, orientation and focussing, forming  complete and very efficient star camera which was suitably and rigidly attached to the tube of the Oddie Telescope.' P. Barrachi, 'Establishment of an Astronomical Observatory at Canberra (Mt. Stromlo). Courtesy of the National Archives of Australia

In addition to the Oddie telescope, the team brings with them:

A portable Transit Instrument, 3½ inch aperture, by Troughton and Simms, lent by the Melbourne Observatory, for which a pier of concrete and a wooden hut with appropriate shutters were built in May, 1912. 

From, Canberra Capital City of the Commonwealth of Australia, 1913 report

Tests corroborate, Mount Stromlo is the perfect site.