Arkaroola Remote Observatory - South Australia
In 2009 I was offered a position at Ellex, a medical laser manufacturer in Adelaide, Australia. After years of backyard astronomy from just outside of Ottawa, Canada, in a small village named Carp, moving down under gave me the opportunity to find even darker skies, unexplored by me. I knew that when I came to Adelaide in late 2009 I did not want to set up my telescope in the city. But I also knew that I did not want to commute dozens of miles to work everyday to live in a semi-light polluted area. I thought it might be possible to set up the telescope remotely and that Australia provided great skies for such a venture. But where? Since I had never built a fully automated remote observatory before I needed it to be accessible by road and close enough so that it could be built and debugged over several trips. I knew full well that an automated observatory would require many iterations to iron out all the kinks.
Just after moving to Adelaide, I met with a couple guys also interested in astronomy and we spent a few nights stargazing near the town of Hawker at the base of the Northern Flinders Ranges in South Australia. The skies were fantastic. From there, we discussed setting up further north in the Flinders, and Arkaroola became the choice destination.
Arkaroola is renown for amateur astronomy as there are a number of observatories for visual there and regular astronomy tours are given to visitors, not to mention the lack of light pollution and the glorious skies. In late November 2010, after being granted permission to use the roll off observatory to set up our personal telescopes, myself and two mates headed north armed with mounts, telescopes, imaging equipment, laptops and batteries.
First Visit to Arkaroola Wilderness Sanctuary - November 2010
View from Arkaroola visitor center
Upon arrival to the village visitors are treated to a spectacular view of a jagged outcrop of slanted layers named Griselda Hill. The purpose of my first visit to the Arkaroola Wilderness Sanctuary was to run my relatively new scope through its paces and get a feeling for the sky quality in the area. We set up our equipment in the Reginald Sprigg Observatory overlooking the village. It is a roll-off roof observatory built in 2003 for the use of guests and visitors.
Imaging setup in the roll-off roof observatory
My telescope was a PlaneWave Instruments 0.5m f/6.8 corrected Dall-Kirkham Cassegrain with a carbon fiber truss. The equatorial mount was a Software Bisque Paramount MME with a counterweight bar extension shaft and extra counterweights! The mount was really at the limit of its capacity for the 140 lbs OTA. The CCD camera was an SBIG ST8-XME with a 10 position filter and AO-8 tip-tilt guider. A blue anodized Optec Pyxis instrument rotator was used to increase the chances of locating a suitable guide star for automatic tracking adjustments. Because of the fairly long imaging train and fixed backfocus distance for this type of telescope, the stock focuser was substituted for a low profile Clement 3.5" Bellerophon focuser which was motorized by a Robofocus stepper motor unit. All the equipment was connected via through the mount cabling to a computer for control by MaxIm DL, a CCD image acquisition software application. Power was supplied by 100 Ah battery and small inverter. The battery was lugged down to the village each day to be recharged for the next night.
Sunset with young moon over Arkaroola village from R.C. Sprigg Observatory
The view towards the western horizon from the roll-off observatory at sunset displayed amazing colors, the peaks in the distance turning ochre, then disappearing into the shadows. Since everything in the village is powered via diesel generator and the operators are very considerate of the needs of astronomy, the village lights, seen in the foreground, are few and discrete.
Telescope cooling down in roll-off roof observatory
While waiting for astronomical darkness the scope is pointed near the zenith to cool off. Later, acquisition commenced on a few objects, most notably a closeup image of the Horsehead nebula and the faint interacting galaxies IC1622/23 cataloged by Halton Arp from mount Palomar as Arp 236.
Image of Horsehead nebula and interacting galaxies IC1622/23
The extremely transparent skies are typical for this area which receives only about 220 mm of rain annually, and boasts nearly the same clear skies as the professional observatory in La Silla, Chile. The bar chart below shows the cloud cover averaged over many years in Oktas where 0 = no clouds and 8 = overcast. The data for my previous observatory in Ottawa, Ontario along with the Siding Spring Observatory near Connabarabran, New South Wales is shown for comparison. The data was extracted from the Environment Canada website, the Australian Bureau of Meteorology website and the European Southern Observatory Users Manual (Schwarz & Melnik 1993).
The astronomical seeing was also measured at Freeling Heights, about 15km north of Arkaroola, in 1993. The zenith seeing disk was almost always smaller than 2", with the most common readings at ~1.2". A nearly simultaneous measurement was conducted at SSO with the duplicate equipment. The full paper: Seeing Measurements at Freeling-Heights and Siding-Spring Observatory by Wood, Rodgers and Russell is available here.
After this trip we were enthralled with the skies and decided to look into setting something up in Arkaroola. The roll off roof would not work for a number of reasons: it was not fully sealed against dust, it could not be easily motorized and it was used by guests quite regularly for visual astronomy. However we asked the owner of Arkaroola, Doug Sprigg, if there was another place nearby where we could set up some automated domes. He came back to us with pictures of the Spriggina Lookout and we decided to check it out.