SKY AND SPACE with Dr Colin Keay
Colin has published a vast array of
articles over the years with the Newcastle Herald. Here you will
find those articles with a new feature article presentation on
this page each month.
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SKY AND SPACE – December 1987
By Professor Colin Keay, University of Newcastle
Siding Spring Observatory
The holiday season is fast approaching and many more families
will be heading with their caravans or camping gear for the
Warrumbungle Mountains, one of the best beauty spots of inland
New South Wales. The Warrumbungles are the home of Australia’s
greatest collection of telescopes at the Siding Spring
Observatory not far from Coonabarabran. A visit to the
Observatory is a must for travellers and holidaymakers in the
region.
In the largest dome atop the Siding Spring Mountain is the
Anglo-Australian 3.9 metre telescope. That’s 150 inches in
ancient measure, and refers to the diameter of the telescope’s
primary mirror which gathers the light from stars and galaxies
less than one millionth as bright as the faintest star our
feeble eyes can perceive. Its only rivals in the Southern
Hemisphere are the Inter-American Observatory’s 4.0 metre
telescope at Cerro Tololo and European Southern Observatory’s
3.6 metre instrument at la Cilla, both in Chile.
In many respects the AAT, as it is generally called, is the
best telescope of the three. This is due to two factors: its
excellent design and the superb instrumentation developed for
it, which increases the telescope’s power considerably. Tiny
semi-conductor devices called "charge-coupled detectors", or
CCd’s can register single photons of light, which is rather more
economical than the hundred or so needed to from a star image on
a photographic plate.
When night falls over Siding Spring Mountain the dome doors
slide open and every moment of clear-sky viewing is used to
greatest advantage. British and Australian astronomers have
strictly equal shares of the viewing time, which is so keenly
sought after that even the top astronomers get only a few nights
per year. There is no time for idle star-gazing. As far as
visitors are concerned, a view through the telescope would be a
disappointment: far better are the beautiful photographs on
display taken by such experts as David Malin. Look for one of
the Tarantula Nebula and the Supernova 1987A. Remember that the
whole picture is of an area of sky smaller than the size of the
Moon and will begin to appreciate the power of the AAT.
Mention of the Supernova brings to mind one of the observing
feats of the AAT. Every night since the Supernova burst forth
last February, one hour of AAT observing time has been specially
ear-marked to monitor this greatest astronomical event since the
invention of the telescope. A group of astronomers from Imperial
College in London have used a special computing technique to
combine many images of the Supernova. Due to distortion by the
Earth’s atmosphere, each image is unavoidably blurred. Its like
hot-day shimmer, except that big telescopes suffer from it at
night. Anyway, the combination of images revealed a second
object 70 thousandths of an arc-second away from the supernova
that had not been there beforehand! The nature of the second
object is a mystery, some astronomers are inclined to think that
it could be the flash of the supernova being reflected off a
previously invisible gas cloud nearby. Making such an
observation is equivalent to photographing from Mount Sugarloaf
a shirt button on a man walking beside the Obelisk!
Siding Springs website links..
http://msowww.anu.edu.au/
http://www.aao.gov.au/
http://en.wikipedia.org/wiki/Siding_Spring_Observatory
Information about how to get to Siding Springs..
http://www.pleasetakemeto.com/australia/siding-springs/information
