Rights: © Copyright 2009. University of Waikato. All Rights Reserved. Published 1 April 2009 Download

Professor Denis Sullivan, from Victoria University of Wellington, explains how he uses telescopes, photometers and digital cameras in his research.


The early astronomers, you go back hundreds and hundreds of years, the only equipment they had was the eye. But it’s not a very accurate way of measuring things just by eyeballing things, so most of my work has been done on a photometer.

Photometers are special instruments that convert light into electrical signals and then you can monitor how the light levels change. Most of my work up ‘til recently has been using a photometer which makes use of what’s called photo moloplyer tubes. They are miraculous devices really.

But just recently I've moved to another fairly miraculous device called a CCD, Charge Couple Device, and that’s none other than our digital cameras that are all around. Now everyone knows about digital cameras. But in the case of astronomy, they are refined to a very high degree so that you can detect very, very faint sources of light.

So for the star that I’ve been most interested in for quite a long time, EC20 058-5234, I’ve spent a lot of time observing that with the one metre telescope at Mount John University Observatory, run by the University of Canterbury, who have been very generous in allocating me time down there. So this is a 1 metre diameter telescope and that’s adequate and quite good for the purposes of measuring this particular faint star with a photometer.

Now in 2004 I was able to get some time on a much larger telescope in Chile, because we wanted to make measurements of the brightness of this object that I’ve been studying as a function of wave length. Now the Magellan Telescope had an aperture of 6.5 metre – a huge telescope. So if you compare the 1 metre telescope, the Magellan 6.5 metre telescope in Chile collected 40 times as much light and that was necessary because we wanted to spread the light across different colours in a spectral photometer form to make measurements that way.