You’d think something billed as the world’s largest digital camera would be able to take close-ups of the Moon.
It’s actually not too far from the truth. The camera, called MegaPrime, has been fitted to the Canada France Hawaii Telescope (CFHT) on the summit of Mauna Kea in Hawaii. It will be
used to generate images of larger portions of the night sky and has already discovered previously unknown moons of Jupiter in trials.
MegaPrime is a joint Canadian/American/French project. The Herzberg Institute of Astrophysics, part of the National Research Council of Canada, contributed some of the research and design work.
“”It is basically an intrument that is replacing an older instrument on the telescope,”” explained Joeleff Fitzsimmons, engineer in training for the NRC-HIA. “”We’re still using the Canada France Hawaii Telescope, which is a 3.6-meter class telescope, but it replaces the end part of the optics. Light still comes in through the telescope and then goes up through the new optics and into the new camera.””
The digital camera contains 40 imaging devices, each one with 2,000 by 4,500 pixels, which is on the order of 360 mega-pixels, according to Fitzsimmons. By comparison, most consumer digital cameras typically have about five mega-pixels.
Many of the components were manufactured in Hawaii, but some of the work was done in Ontario. A Kingston company called Wejay, for example, manufactured parts of the focus stage of the camera.
Traditionally, camera work was done with photographic plates, said Dr. David Bohlender, a senior research officer with the NRC-HIA. “”The problem with that technology was that they were very inefficient. They would detect maybe one per cent of the photons actually hitting the plate. You would have to see 100 photons before you could see one pixel activated, whereas these new detectors are sensitive to about 80 per cent of the photons colliding,”” he said.
The digital camera’s main purpose is a 475-night survey done over five years. The survey will be divided into three components to look at different aspects of the universe. MegaPrime will be used to scan for objects like Pluto, for example, which is now considered to be an asteroid — not the planet that it was originally believed to be. Another project will see the MegaPrime use something called gravitational lensing to probe how mass is distributed in the universe.
The technology may have some applications with other observatories around the world, said Fitzsimmons, but it’s doubtful it will be replicated for another telescope. By the time these projects are usually completed, they’re already out-of-date, and the industry has moved to the next generation of technology.