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The hunt for Near Earth Objects (NEOs) with the potential to threaten our planet has, until recently, been very much limited to the Northern Hemisphere. Now astronomers are to search for NEOs in the southern skies using a refurbished telescope at the Australian National University's Siding Spring Observatory.
The group known as the Siding Spring Survey (SSS) discovered their first two near-Earth asteroids on 29 March. Astronomer Gordon Garradd detected the asteroids in images he obtained with the 0.5 metre Uppsala Schmidt telescope. Garradd�s SSS colleague, Robert H. McNaught confirmed both discoveries in images he took with the Siding Spring 1 metre telescope that same night.
The Uppsala Schmidt telescope was built in the 1950s for Uppsala Observatory in Sweden. It was sited at Stromlo as the Uppsala Southern Station to make wide field photographs of the southern sky. Increasing light pollution from Canberra led to its relocation to Siding Spring, near Coonabarabran in New South Wales, in late 1982. Despite its high quality optics, the telescope drifted into disuse because it used photographic film rather than modern electronic detectors and had to be operated manually.
In 1999, McNaught and Stephen M. Larson of UA's Lunar and Planetary Laboratory joined in an effort to refurbish and upgrade the Uppsala telescope. Larson had similarly just overhauled a manually operated, photographic wide-field Schmidt telescope in the Santa Catalina Mountains north of Tucson for his Catalina Sky Survey (CSS), part of the NASA-funded programme to detect and track potentially hazardous asteroids.
The SSS builds on telescope control, detector technology and software developed for the CSS in Tucson. During the upgrade, the Uppsala was completely reconditioned, and fitted with computer control, a large format (16 megapixel) solid state detector array, and extensive support computers and software that detects objects moving against background stars.
Larson said his reaction to the SSS milestone was "one of relief, since it took several years to make the telescope and facility modifications. Now the real work begins."
McNaught and Garradd will operate SSS about 20 nights each month. They suspend operations when the week around full moon brightens the sky, making faint object detection difficult. The Catalina telescope, which Larson and his team upgraded again in May 2000, features new optics that give it a 69 centimetre aperture and a new, more sensitive camera. Both CSS and SSS telescopes can detect objects as faint as 20th magnitude.
The SSS plan is to use the 1-meter (40-inch) telescope for part of the month to quickly confirm suspect asteroids detected with the Uppsala, freeing the smaller telescope to continue it searches.
The new survey is a joint collaboration between the University of Arizona Lunar and Planetary Laboratory and ANU's Research School of Astronomy and Astrophysics, and is funded by NASA�s Near-Earth Object Observation Programme.
More info: Siding Springs
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