ASTROSAT: Unusual celestial objects need special detectors

ASTROSAT will carry four X-ray telescopes and two ultra-violet telescopes.
ASTROSAT will carry four X-ray telescopes and two ultra-violet telescopes.
(Image: John Hutchings)

"All of the hottest and most exotic objects in the universe radiate strongly in the ultraviolet range," says Dr. John Hutchings of the Herzberg Institute of Astrophysics. He is speaking about stars such as hot white dwarfs and neutron stars, black holes and quasars that are seen principally in UV and X-ray wavelengths.

"By exploring distant galaxies in the UV range, we can study the formation and life cycle of galaxies, and star formation within galaxies. That's one of the science drivers of this project," he says.

Hutchings' project is the building of two detectors for UVIT, two ultraviolet imaging telescopes on India's ASTROSAT space telescope set to launch in 2014. He is principal investigator for the Canadian science team.

New territory for Canadian technology

"This is a technology that Canada has never developed before," says Hutchings, "to detect ultraviolet light at a very low-level. The detectors count each photon of light as it arrives and records its location and time of arrival. These are then stored, and an image is created."

Black holes, neutron stars, pulsars, white dwarfs, quasars, and active galactic nuclei are just some of the cosmic objects that ASTROSAT will offer a glimpse of. "These are not your run-of-the-mill stars and galaxies. They're so powerful, they affect the whole universe," Hutchings points out. "We'll be able to see where they form and study their brightness, distribution, life cycle, and more."

A galaxy, as seen in ultraviolet and visible light.     A galaxy, as seen in ultraviolet and visible light.
A galaxy, as seen in ultraviolet and visible light. (Photos: John Hutchings)

The Indian Space Research Organization's ASTROSAT observatory will carry six telescopes: four to make observations in X-ray wavelengths, and two to observe in the UV and visible. The Canadian Space Agency is funding this partnership with ISRO, through a contract with Routes AstroEngineering in Ottawa, for designing and fabrication the detectors, and support for participation by the Herzberg Institute of Astrophysics. The project's team of astronomers from Canadian universities is supported by a grant from the Natural Sciences and Engineering Research Council to set up and run a laboratory at the University of Calgary for calibrating and checking the detectors before shipping to India.

Research opportunities

Canada's participation in ASTROSAT entitles the UVIT team and other Canadian scientists to observation time on the satellite. This means opportunities for new astronomy research by Canadian scientists: a panel will select the best proposals and these will be awarded access to the telescope.